Patent Publication Number: US-2023150863-A1

Title: Ion-exchangeable mixed alkali aluminosilicate glasses

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/164,060 filed on Feb. 1, 2021, which is a continuation of U.S. patent application Ser. No. 16/202,767 filed on Nov. 28, 2018, which also claims the benefit of priority of U.S. Provisional Application Ser. No. 62/591,958 filed on Nov. 29, 2017, the contents of which are relied upon and incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Field 
     The present specification generally relates to glass compositions suitable for use as cover glass for electronic devices. More specifically, the present specification is directed to mixed alkali aluminosilicate glasses that may be formed into cover glass for electronic devices by fusion drawing. 
     Technical Background 
     The mobile nature of portable devices, such as smart phones, tablets, portable media players, personal computers, and cameras, makes these devices particularly vulnerable to accidental dropping on hard surfaces, such as the ground. These devices typically incorporate cover glasses, which may become damaged upon impact with hard surfaces. In many of these devices, the cover glasses function as display covers, and may incorporate touch functionality, such that use of the devices is negatively impacted when the cover glasses are damaged. 
     There are two major failure modes of cover glass when the associated portable device is dropped on a hard surface. One of the modes is flexure failure, which is caused by bending of the glass when the device is subjected to dynamic load from impact with the hard surface. The other mode is sharp contact failure, which is caused by introduction of damage to the glass surface. Impact of the glass with rough hard surfaces, such as asphalt, granite, etc., can result in sharp indentations in the glass surface. These indentations become failure sites in the glass surface from which cracks may develop and propagate. 
     Glass can be made more resistant to flexure failure by the ion-exchange technique, which involves inducing compressive stress in the glass surface. However, the ion-exchanged glass will still be vulnerable to dynamic sharp contact, owing to the high stress concentration caused by local indentations in the glass from the sharp contact. 
     It has been a continuous effort for glass makers and handheld device manufacturers to improve the resistance of handheld devices to sharp contact failure. Solutions range from coatings on the cover glass to bezels that prevent the cover glass from impacting the hard surface directly when the device drops on the hard surface. However, due to the constraints of aesthetic and functional requirements, it is very difficult to completely prevent the cover glass from impacting the hard surface. 
     It is also desirable that portable devices be as thin as possible. Accordingly, in addition to strength, it is also desired that glasses to be used as cover glass in portable devices be made as thin as possible. Thus, in addition to increasing the strength of the cover glass, it is also desirable for the glass to have mechanical characteristics that allow it to be formed by processes that are capable of making thin glass articles, such as thin glass sheets. 
     Accordingly, a need exists for glasses that can be strengthened, such as by ion exchange, and that have the mechanical properties that allow them to be formed as thin glass articles. 
     SUMMARY 
     According to a first embodiment, a glass composition comprises: from greater than or equal to 55.0 mol % to less than or equal to 75.0 mol % SiO 2 ; from greater than or equal to 8.0 mol % to less than or equal to 20.0 mol % Al 2 O 3 ; from greater than or equal to 3.0 mol % to less than or equal to 15.0 mol % Li 2 O; from greater than or equal to 5.0 mol % to less than or equal to 15.0 mol % Na 2 O; and less than or equal to 1.5 mol % K 2 O, wherein Al 2 O 3 +Li 2 O is greater than 22.5 mol %, R 2 O+RO is greater than or equal to 18.0 mol %, R 2 O/Al 2 O 3  is greater than or equal to 1.06, SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5  is greater than or equal to 78.0 mol %, and (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is greater than or equal to 8.0. 
     According to a second embodiment, a glass article comprises: a first surface; a second surface opposite the first surface, wherein a thickness (t) of the glass article is measured as a distance between the first surface and the second surface; and a compressive stress layer extending from at least one of the first surface and the second surface into the thickness (t) of the glass article, wherein a central tension of the glass article is greater than or equal to 30 MPa, the compressive stress layer has a depth of compression that is from greater than or equal to 0.15t to less than or equal to 0.25t, and the glass article is formed from a glass comprising: from greater than or equal to 55.0 mol % to less than or equal to 75.0 mol % SiO 2 ; from greater than or equal to 8.0 mol % to less than or equal to 20.0 mol % Al 2 O 3 ; from greater than or equal to 3.0 mol % to less than or equal to 15.0 mol % Li 2 O; from greater than or equal to 5.0 mol % to less than or equal to 15.0 mol % Na 2 O; and less than or equal to 1.5 mol % K 2 O, wherein Al 2 O 3 +Li 2 O is greater than 22.5 mol %, R 2 O+RO is greater than or equal to 18.0 mol %, R 2 O/Al 2 O 3  is greater than or equal to 1.06, SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5  is greater than or equal to 78.0 mol %, and (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is greater than or equal to 8.0. 
     According to a third embodiment, a glass article comprises: a first surface; a second surface opposite the first surface, wherein a thickness (t) of the glass article is measured as a distance between the first surface and the second surface; and a compressive stress layer extending from at least one of the first surface and the second surface into the thickness (t) of the glass article, wherein a central tension of the glass article is greater than or equal to 60 MPa, the compressive stress layer has a depth of compression that is from greater than or equal to 0.15t to less than or equal to 0.25t, and the glass article has a composition at a center depth of the glass article comprising: from greater than or equal to 55.0 mol % to less than or equal to 75.0 mol % SiO 2 ; from greater than or equal to 8.0 mol % to less than or equal to 20.0 mol % Al 2 O 3 ; from greater than or equal to 3.0 mol % to less than or equal to 15.0 mol % Li 2 O; from greater than or equal to 5.0 mol % to less than or equal to 15.0 mol % Na 2 O; and less than or equal to 1.5 mol % K 2 O, wherein Al 2 O 3 +Li 2 O is greater than 22.5 mol %, R 2 O+RO is greater than or equal to 18.0 mol %, R 2 O/Al 2 O 3  is greater than or equal to 1.06, SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5  is greater than or equal to 78.0 mol %, and (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is greater than or equal to 8.0. 
     Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    schematically depicts a cross section of a glass having compressive stress layers on surfaces thereof according to embodiments disclosed and described herein; 
         FIG.  2 A  is a plan view of an exemplary electronic device incorporating any of the glass articles disclosed herein; and 
         FIG.  2 B  is a perspective view of the exemplary electronic device of  FIG.  2 A . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to alkali aluminosilicate glasses according to various embodiments. Alkali aluminosilicate glasses have good ion exchangeability, and chemical strengthening processes have been used to achieve high strength and high toughness properties in alkali aluminosilicate glasses. Sodium aluminosilicate glasses are highly ion exchangeable glasses with high glass formability and quality. The substitution of Al 2 O 3  into the silicate glass network increases the interdiffusivity of monovalent cations during ion exchange. By chemical strengthening in a molten salt bath (e.g., KNO 3  and/or NaNO 3 ), glasses with high strength, high toughness, and high indentation cracking resistance can be achieved. 
     Therefore, alkali aluminosilicate glasses with good physical properties, chemical durability, and ion exchangeability have drawn attention for use as cover glass. In particular, lithium containing aluminosilicate glasses, which have lower annealing and softening temperatures, lower coefficient of thermal expansion (CTE) values, and fast ion exchangeability, are provided herein. Through different ion exchange processes, greater central tension (CT), depth of compression (DOC), and high compressive stress (CS) can be achieved. However, the addition of lithium in the alkali aluminosilicate glass may reduce the melting point, softening point, or liquidus viscosity of the glass. 
     Drawing processes for forming glass articles, such as, for example, glass sheets, are desirable because they allow a thin glass article to be formed with few defects. It was previously thought that glass compositions were required to have relatively high liquidus viscosities—such as a liquidus viscosity greater than 1000 kP, greater than 1100 kP, or greater than 1200 kP—to be formed by a drawing process, such as, for example, fusion drawing or slot drawing. However, developments in drawing processes allow glasses with lower liquidus viscosities to be used in drawing processes. Thus, glasses used in drawing processes may include more lithia than previously thought, and may include more glass network forming components, such as, for example, SiO 2 , Al 2 O 3 , B 2 O 3 , and P 2 O 5 . Accordingly, a balance of the various glass components that allows the glass to realize the benefits of adding lithium and glass network formers to the glass composition, but that does not negatively impact the glass composition are provided herein. 
     In embodiments of glass compositions described herein, the concentration of constituent components (e.g., SiO 2 , Al 2 O 3 , Li 2 O, and the like) are given in mole percent (mol %) on an oxide basis, unless otherwise specified. Components of the alkali aluminosilicate glass composition according to embodiments are discussed individually below. It should be understood that any of the variously recited ranges of one component may be individually combined with any of the variously recited ranges for any other component. 
     In embodiments of the alkali aluminosilicate glass compositions disclosed herein, SiO 2  is the largest constituent and, as such, SiO 2  is the primary constituent of the glass network formed from the glass composition. Pure SiO 2  has a relatively low CTE and is alkali free. However, pure SiO 2  has a high melting point. Accordingly, if the concentration of SiO 2  in the glass composition is too high, the formability of the glass composition may be diminished as higher concentrations of SiO 2  increase the difficulty of melting the glass, which, in turn, adversely impacts the formability of the glass. In embodiments, the glass composition generally comprises SiO 2  in an amount from greater than or equal to 55.0 mol % to less than or equal to 75.0 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition comprises SiO 2  in amounts greater than or equal to 58.0 mol %, such as greater than or equal to 60.0 mol %, greater than or equal to 62.0 mol %, greater than or equal to 64.0 mol %, greater than or equal to 66.0 mol %, greater than or equal to 68.0 mol %, or greater than or equal to 70.0 mol %. In embodiments, the glass composition comprises SiO 2  in amounts less than or equal to 72.0 mol %, such as less than or equal to 70.0 mol %, less than or equal to 68.0 mol %, less than or equal to 66.0 mol %, less than or equal to 64.0 mol %, or less than or equal to 62.0 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition comprises SiO 2  in an amount from greater than or equal to 58.0 mol % to less than or equal to 70.0 mol %, such as from greater than or equal to 60.0 mol % to less than or equal to 68.0 mol %, or from greater than or equal to 62.0 mol % to less than or equal to 64.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     The glass composition of embodiments may further comprise Al 2 O 3 . Al 2 O 3  may serve as a glass network former, similar to SiO 2 . Al 2 O 3  may increase the viscosity of the glass composition due to its tetrahedral coordination in a glass melt formed from a glass composition, decreasing the formability of the glass composition when the amount of Al 2 O 3  is too high. However, when the concentration of Al 2 O 3  is balanced against the concentration of SiO 2  and the concentration of alkali oxides in the glass composition, Al 2 O 3  can reduce the liquidus temperature of the glass melt, thereby enhancing the liquidus viscosity and improving the compatibility of the glass composition with certain forming processes, such as the fusion forming process. In embodiments, the glass composition generally comprises Al 2 O 3  in a concentration of from greater than or equal to 8.0 mol % to less than or equal to 20.0 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition comprises Al 2 O 3  in amounts greater than or equal to 10.0 mol %, such as greater than or equal to 12.0 mol %, greater than or equal to 14.0 mol %, greater than or equal to 16.0 mol %, greater than or equal to 17.0 mol %, or greater than or equal to 19.0 mol %. In embodiments, the glass composition comprises Al 2 O 3  in amounts less than or equal to 19.0 mol %, such as less than or equal to 18.0 mol %, less than or equal to 17.0 mol %, less than or equal to 16.0 mol %, less than or equal to 15.0 mol %, less than or equal to 14.0 mol %, or less than or equal to 13.0 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition comprises Al 2 O 3  in an amount from greater than or equal to 10.0 mol % to less than or equal to 18.0 mol %, such as from greater than or equal to 12.0 mol % to less than or equal to 16.0 mol %, or from greater than or equal to 15.0 mol % to less than or equal to 17.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     Like SiO 2  and Al 2 O 3 , P 2 O 5  may be added to the glass composition as a network former, thereby reducing the meltability and formability of the glass composition. Thus, P 2 O 5  may be added in amounts that do not overly decrease these properties. The addition of P 2 O 5  may also increase the diffusivity of ions in the glass composition during ion exchange treatment, thereby increasing the efficiency of these treatments. In embodiments, the glass composition may comprise P 2 O 5  in amounts from greater than or equal to 0.0 mol % to less than or equal to 8.0 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition may comprise P 2 O 5  in amounts greater than or equal to 0.5 mol %, greater than or equal to 1.0 mol %, greater than or equal to 1.5 mol %, greater than or equal to 2.0 mol %, greater than or equal to 2.5 mol %, greater than or equal to 3.0 mol %, greater than or equal to 3.5 mol %, greater than or equal to 4.0 mol %, or greater than or equal to 4.5 mol %. In embodiments, the glass composition may comprise P 2 O 5  in an amount less than or equal to 7.5 mol %, less than or equal to 7.0 mol %, less than or equal to 6.5 mol %, less than or equal to 6.0 mol %, less than or equal to 5.5 mol %, less than or equal to 5.0 mol %, less than or equal to 4.5 mol %, less than or equal to 4.0 mol %, less than or equal to 3.5 mol %, less than or equal to 3.0 mol %, less than or equal to 2.5 mol %, less than or equal to 2.0 mol %, less than or equal to 1.5 mol %, less than or equal to 1.0 mol %, or less than or equal to 0.5 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition may comprise P 2 O 5  in amounts from greater than or equal to 0.5 mol % to less than or equal to 7.5 mol %, from greater than or equal to 1.0 mol % to less than or equal to 7.0 mol %, from greater than or equal to 1.5 mol % to less than or equal to 6.5 mol %, from greater than or equal to 2.0 mol % to less than or equal to 6.0 mol %, from greater than or equal to 2.5 mol % to less than or equal to 5.5 mol %, or from greater than or equal to 3.0 mol % to less than or equal to 5.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     Like SiO 2 , Al 2 O 3 , and P 2 O 5 , B 2 O 3  may be added to the glass composition as a network former, thereby reducing the meltability and formability of the glass composition. Thus, B 2 O 3  may be added in amounts that do not overly decrease these properties. In embodiments, the glass composition may comprise B 2 O 3  in amounts from greater than or equal to 0.0 mol % B 2 O 3  to less than or equal to 3.0 mol % B 2 O 3 , and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition may comprise B 2 O 3  in amounts greater than or equal to 0.5 mol %, greater than or equal to 1.0 mol %, greater than or equal to 1.5 mol %, greater than or equal to 2.0 mol %, or greater than or equal to 2.5 mol %. In embodiments, the glass composition may comprise B 2 O 3  in an amount less than or equal to 2.5 mol %, less than or equal to 2.0 mol %, less than or equal to 1.5 mol %, less than or equal to 1.0 mol %, or less than or equal to 0.5 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition comprises B 2 O 3  in amounts from greater than or equal to 0.5 mol % to less than or equal to 2.5 mol %, or from greater than or equal to 1.0 mol % to less than or equal to 2.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     In some embodiments, the glass composition comprises at least one of B 2 O 3  and P 2 O 5  as glass network forming elements. Accordingly, in embodiments B 2 O 3 +P 2 O 5  is greater than 0.0 mol %, such as greater than or equal to 0.5 mol %, greater than or equal to 1.0 mol %, greater than or equal to 1.5 mol %, greater than or equal to 2.0 mol %, greater than or equal to 2.5 mol %, greater than or equal to 3.0 mol %, greater than or equal to 3.5 mol %, greater than or equal to 4.0 mol %, greater than or equal to 4.5 mol %, greater than or equal to 5.0 mol %, greater than or equal to 5.5 mol %, greater than or equal to 6.0 mol %, greater than or equal to 6.5 mol %, greater than or equal to 7.0 mol %, greater than or equal to 7.5 mol %, or greater than or equal to 8.0 mol %, and all ranges and sub-ranges between the foregoing values. In embodiments, B 2 O 3 +P 2 O 5  is less than or equal to 7.5 mol %, such as less than or equal to 7.0 mol %, less than or equal to 6.5 mol %, less than or equal to 6.0 mol %, less than or equal to 5.5 mol %, less than or equal to 5.0 mol %, less than or equal to 4.5 mol %, less than or equal to 4.0 mol %, less than or equal to 3.5 mol %, less than or equal to 3.0 mol %, less than or equal to 2.5 mol %, less than or equal to 2.0 mol %, less than or equal to 1.5 mol %, less than or equal to 1.0 mol %, or less than or equal to 0.5 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition comprises B 2 O 3 +P 2 O 5  in amounts from greater than or equal to 0.5 mol % to less than or equal to 7.5 mol %, greater than or equal to 1.0 mol % to less than or equal to 7.0 mol %, greater than or equal to 1.5 mol % to less than or equal to 6.5 mol %, greater than or equal to 2.0 mol % to less than or equal to 6.0 mol %, greater than or equal to 2.5 mol % to less than or equal to 5.5 mol %, or greater than or equal to 3.0 mol % to less than or equal to 5.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     The effects of Li 2 O in the glass composition are discussed above and discussed in further detail below. In part, the addition of lithium in the glass allows for better control of an ion exchange process and further reduces the softening point of the glass. In embodiments, the glass composition generally comprises Li 2 O in an amount from greater than or equal to 3.0 mol % to less than or equal to 15.0 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition comprises Li 2 O in amounts greater than or equal to 3.5 mol %, greater than or equal to 4.0 mol %, greater than or equal to 4.5 mol %, greater than or equal to 5.0 mol %, greater than or equal to 5.5 mol %, greater than or equal to 6.0 mol %, greater than or equal to 6.5 mol %, greater than or equal to 7.0 mol %, greater than or equal to 7.5 mol %, greater than or equal to 8.0 mol %, greater than or equal to 8.5 mol %, greater than or equal to 9.0 mol %, greater than or equal to 9.5 mol %, greater than or equal to 10.0 mol %, greater than or equal to 10.5 mol %, greater than or equal to 11.0 mol %, greater than or equal to 11.5 mol %, greater than or equal to 12.0 mol %, greater than or equal to 12.5 mol %, greater than or equal to 13.0 mol %, greater than or equal to 13.5 mol %, greater than or equal to 14.0 mol %, or greater than or equal to 14.5 mol %. In some embodiments, the glass composition comprises Li 2 O in amounts less than or equal to 14.5 mol %, less than or equal to 14.0 mol %, less than or equal to 13.5 mol %, less than or equal to 13.0 mol %, less than or equal to 12.5 mol %, less than or equal to 12.0 mol %, less than or equal to 11.5 mol %, less than or equal to 11.0 mol %, less than or equal to 10.5 mol %, less than or equal to 10.0 mol %, less than or equal to 9.5 mol %, less than or equal to 9.0 mol %, less than or equal to 8.5 mol %, less than or equal to 8.0 mol %, less than or equal to 7.5 mol %, less than or equal to 7.0 mol %, less than or equal to 6.5 mol %, less than or equal to 6.0 mol %, less than or equal to 5.5 mol %, less than or equal to 5.0 mol %, less than or equal to 4.5 mol %, less than or equal to 4.0 mol %, or less than or equal to 3.5 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition comprises Li 2 O in an amount from greater than or equal to 3.5 mol % to less than or equal to 14.5 mol %, such as from greater than or equal to 4.0 mol % to less than or equal to 14.0 mol %, from greater than or equal to 4.5 mol % to less than or equal to 13.5 mol %, from greater than or equal to 5.0 mol % to less than or equal to 13.0 mol %, from greater than or equal to 5.5 mol % to less than or equal to 12.5 mol %, from greater than or equal to 6.0 mol % to less than or equal to 12.0 mol %, from greater than or equal to 6.5 mol % to less than or equal to 11.5 mol %, or from greater than or equal to 7.0 mol % to less than or equal to 10.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     In addition to being a glass network forming component, Al 2 O 3  also aids in increasing the ion exchangeability of the glass composition. Therefore, in embodiments, the amount of Al 2 O 3  and other components that may be ion exchanged may be relatively high. For example, Li 2 O is an ion exchangeable component. In some embodiments, the amount of Al 2 O 3 +Li 2 O in the glass composition may be greater than 22.5 mol %, such as greater than or equal to 23.0 mol %, greater than or equal to 23.5 mol %, greater than or equal to 24.0 mol %, greater than or equal to 24.5 mol %, greater than or equal to 25.0 mol %, greater than or equal to 25.5 mol %, or greater than or equal to 26.0 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the amount of Al 2 O 3 +Li 2 O is less than or equal to 26.5 mol %, such as less than or equal to 26.0 mol %, less than or equal to 25.5 mol %, less than or equal to 25.0 mol %, less than or equal to 24.5 mol %, less than or equal to 24.0 mol %, less than or equal to 23.5 mol %, or less than or equal to 23.0 mol %, and all ranges and sub-ranges between the foregoing values. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the amount of Al 2 O 3 +Li 2 O is from greater than or equal to 23.0 mol % to less than or equal to 26.5 mol %, from greater than or equal to 23.5 mol % to less than or equal to 26.0 mol %, from greater than or equal to 24.0 mol % to less than or equal to 25.5 mol %, or from greater than or equal to 24.5 mol % to less than or equal to 25.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     According to embodiments, the glass composition may also comprise alkali metal oxides other than Li 2 O, such as Na 2 O. Na 2 O aids in the ion exchangeability of the glass composition, and also increases the melting point of the glass composition and improves formability of the glass composition. However, if too much Na 2 O is added to the glass composition, the CTE may be too low, and the melting point may be too high. In embodiments, the glass composition generally comprises Na 2 O in an amount from greater than 5.0 mol % Na 2 O to less than or equal to 15 mol % Na 2 O, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition comprises Na 2 O in amounts greater than or equal to 5.5 mol %, greater than or equal to 6.0 mol %, greater than or equal to 6.5 mol %, greater than or equal to 7.0 mol %, greater than or equal to 7.5 mol %, greater than or equal to 8.0 mol %, greater than or equal to 8.5 mol %, greater than or equal to 9.0 mol %, greater than or equal to 9.5 mol %, greater than or equal to 10.0 mol %, greater than or equal to 10.5 mol %, greater than or equal to 11.0 mol %, greater than or equal to 11.5 mol %, greater than or equal to 12.0 mol %, greater than or equal to 12.5 mol %, greater than or equal to 13.0 mol %, greater than or equal to 13.5 mol %, greater than or equal to 14.0 mol %, or greater than or equal to 14.5 mol %. In some embodiments, the glass composition comprises Na 2 O in amounts less than or equal to 14.5 mol %, less than or equal to 14.0 mol %, less than or equal to 13.5 mol %, less than or equal to 13.0 mol %, less than or equal to 12.5 mol %, less than or equal to 12.0 mol %, less than or equal to 11.5 mol %, less than or equal to 11.0 mol %, less than or equal to 10.5 mol %, less than or equal to 10.0 mol %, less than or equal to 9.5 mol %, less than or equal to 9.0 mol %, less than or equal to 8.5 mol %, less than or equal to 8.0 mol %, less than or equal to 7.5 mol %, less than or equal to 7.0 mol %, less than or equal to 6.5 mol %, less than or equal to 6.0 mol %, less than or equal to 5.5 mol %, less than or equal to 5.0 mol %, or less than or equal to 4.5 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition comprises Na 2 O in an amount from greater than or equal to 5.5 mol % to less than or equal to 14.5 mol %, such as from greater than or equal to 6.0 mol % to less than or equal to 14.0 mol %, from greater than or equal to 6.5 mol % to less than or equal to 13.5 mol %, from greater than or equal to 7.0 mol % to less than or equal to 13.0 mol %, from greater than or equal to 7.5 mol % to less than or equal to 12.5 mol %, from greater than or equal to 8.0 mol % to less than or equal to 12.0 mol %, from greater than or equal to 8.5 mol % to less than or equal to 11.5 mol %, or from greater than or equal to 9.0 mol % to less than or equal to 10.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     As noted above, Al 2 O 3  aids in increasing the ion exchangeability of the glass composition. Therefore, in embodiments, the amount of Al 2 O 3  and other components that may be ion exchanged may be relatively high. For example, Li 2 O and Na 2 O are ion exchangeable components. In some embodiments, the amount of Al 2 O 3 +Li 2 O+Na 2 O in the glass composition may be greater than 25.0 mol %, such as greater than or equal to 25.5 mol %, greater than or equal to 26.0 mol %, greater than or equal to 26.5 mol %, greater than or equal to 27.0 mol %, greater than or equal to 27.5 mol %, greater than or equal to 28.0 mol %, greater than or equal to 28.5 mol %, greater than or equal to 29.0 mol %, or greater than or equal to 29.5 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the amount of Al 2 O 3 +Li 2 O+Na 2 O is less than or equal to 30.0 mol %, such as less than or equal to 29.5 mol %, less than or equal to 29.0 mol %, less than or equal to 28.5 mol %, less than or equal to 28.0 mol %, less than or equal to 27.5 mol %, less than or equal to 27.0 mol %, less than or equal to 26.5 mol %, less than or equal to 26.0 mol %, or less than or equal to 25.5 mol %, and all ranges and sub-ranges between the foregoing values. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the amount of Al 2 O 3 +Li 2 O+Na 2 O is from greater than or equal to 25.0 mol % to less than or equal to 30.0 mol %, from greater than or equal to 25.5 mol % to less than or equal to 29.5 mol %, from greater than or equal to 26.0 mol % to less than or equal to 29.0 mol %, from greater than or equal to 26.5 mol % to less than or equal to 28.5 mol %, or from greater than or equal to 27.0 mol % to less than or equal to 28.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     Like Na 2 O, K 2 O also promotes ion exchange and increases the DOC of a compressive stress layer. However, adding K 2 O may cause the CTE to be too low, and the melting point to be too high. In embodiments, the glass composition comprises less than or equal to 1.5 mol % K 2 O, such as less than or equal to 1.0 mol %, or less than or equal to 0.5 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition is substantially free or free of potassium. As used herein, the term “substantially free” means that the component is not added as a component of the batch material even though the component may be present in the final glass in very small amounts as a contaminant, such as less than 0.01 mol %. 
     MgO lowers the viscosity of a glass, which enhances the formability, the strain point and the Young&#39;s modulus, and may improve the ion exchange ability. However, when too much MgO is added to the glass composition, the density and the CTE of the glass composition increase. In embodiments, the glass composition generally comprises MgO in a concentration of from greater than or equal to 0.0 mol % to less than or equal to 4.0 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition comprises MgO in amounts greater than or equal to 0.2 mol %, greater than or equal to 0.5 mol %, greater than or equal to 1.0 mol %, greater than or equal to 1.5 mol %, greater than or equal to 2.0 mol %, greater than or equal to 2.5 mol %, greater than or equal to 3.0 mol %, or greater than or equal to 3.5 mol %. In some embodiments, the glass composition comprises MgO in amounts less than or equal to 3.5 mol %, less than or equal to 3.0 mol %, less than or equal to 2.5 mol %, less than or equal to 2.0 mol %, less than or equal to 1.5 mol %, less than or equal to 1.0 mol %, less than or equal to 0.5 mol %, less than or equal to 0.4 mol %, or less than or equal to 0.2 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition comprises MgO in an amount from greater than or equal to 0.2 mol % to less than or equal to 3.5 mol %, such as from greater than or equal to 0.5 mol % to less than or equal to 3.0 mol %, from greater than or equal to 1.0 mol % to less than or equal to 2.5 mol %, or from greater than or equal to 1.5 mol % to less than or equal to 2.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     CaO lowers the viscosity of a glass, which enhances the formability, the strain point and the Young&#39;s modulus, and may improve the ion exchange ability. However, when too much CaO is added to the glass composition, the density and the CTE of the glass composition increase. In embodiments, the glass composition generally comprises CaO in a concentration of from greater than or equal to 0.0 mol % to less than or equal to 2.0 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition comprises CaO in amounts greater than or equal to 0.2 mol %, greater than or equal to 0.4 mol %, greater than or equal to 0.6 mol %, greater than or equal to 0.8 mol %, greater than or equal to 1.0 mol %, greater than or equal to 1.2 mol %, greater than or equal to 1.4 mol %, greater than or equal to 1.6 mol %, or greater than or equal to 1.8 mol %. In some embodiments, the glass composition comprises CaO in amounts less than or equal to 1.8 mol %, less than or equal to 1.6 mol %, less than or equal to 1.4 mol %, less than or equal to 1.2 mol %, less than or equal to 1.0 mol %, less than or equal to 0.8 mol %, less than or equal to 0.6 mol %, less than or equal to 0.4 mol %, or less than or equal to 0.2 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition comprises CaO in an amount from greater than or equal to 0.2 mol % to less than or equal to 1.8 mol %, such as from greater than or equal to 0.4 mol % to less than or equal to 1.6 mol %, from greater than or equal to 0.6 mol % to less than or equal to 1.4 mol %, or from greater than or equal to 0.8 mol % to less than or equal to 1.2 mol %, and all ranges and sub-ranges between the foregoing values. 
     In embodiments, the glass composition may optionally include one or more fining agents. In some embodiments, the fining agents may include, for example, SnO 2 . In such embodiments, SnO 2  may be present in the glass composition in an amount less than or equal to 0.2 mol %, such as from greater than or equal to 0.0 mol % to less than or equal to 0.1 mol %, and all ranges and sub-ranges between the foregoing values. In embodiments, SnO 2  may be present in the glass composition in an amount from greater than or equal to 0.0 mol % to less than or equal to 0.2 mol %, or greater than or equal to 0.1 mol % to less than or equal to 0.2 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition may be substantially free or free of SnO 2 . 
     ZnO enhances the ion exchange performance of a glass, such as by increasing the compressive stress of the glass. However, adding too much ZnO may increase density and cause phase separation. In embodiments, the glass composition may comprise ZnO in amounts from greater than or equal to 0.0 mol % to less than or equal to 2.5 mol %, such as from greater than or equal to 0.2 mol % to less than or equal to 2.0 mol %, or from greater than or equal to 0.5 mol % to less than or equal to 1.5 mol %, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition may comprise ZnO in amounts greater than or equal to 0.3 mol %, greater than or equal to 0.5 mol %, or greater than or equal to 0.8 mol %. In embodiments, the glass composition may comprise ZnO in amounts less than or equal to 2.0 mol %, such as less than or equal to 1.5 mol %, or less than or equal to 1.0 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. 
     In addition to the above individual components, glass compositions according to embodiments disclosed herein may comprise divalent cation oxides (referred to herein as RO) in amounts from greater than or equal to 0.0 mol % to less than or equal to 5.0 mol %, and all ranges and sub-ranges between the foregoing values. As used herein, divalent cation oxides (RO) include, but are not limited to, MgO, CaO, SrO, BaO, FeO, and ZnO. In some embodiments, the glass composition may comprise RO in an amount greater than or equal to 0.2 mol %, such as greater than or equal to 0.5 mol %, greater than or equal to 1.0 mol %, greater than or equal to 1.5 mol %, greater than or equal to 2.0 mol %, greater than or equal to 2.5 mol %, greater than or equal to 3.0 mol %, greater than or equal to 3.5 mol %, greater than or equal to 4.0 mol %, or greater than or equal to 4.5 mol %. In embodiments, the glass composition may comprise RO in an amount less than or equal to 4.5 mol %, such as less than or equal to 4.0 mol %, less than or equal to 3.5 mol %, less than or equal to 3.0 mol %, less than or equal to 2.5 mol %, less than or equal to 2.0 mol %, less than or equal to 1.5 mol %, less than or equal to 1.0 mol %, or less than or equal to 0.5 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition may comprise RO in amounts from greater than or equal to 0.2 mol % to less than or equal to 4.5 mol %, such as greater than or equal to 0.5 mol % to less than or equal to 4.0 mol %, greater than or equal to 1.0 mol % to less than or equal to 3.5 mol %, greater than or equal to 1.5 mol % to less than or equal to 3.0 mol %, or greater than or equal to 2.0 mol % to less than or equal to 2.5 mol %, and all ranges and sub-ranges between the foregoing values. 
     The amount of alkali metal oxides (also referred to herein as “R 2 O”) and RO in the glass composition may have an effect on the viscosity of the glass composition, namely the softening point is decreased with increasing R 2 O+RO content to enable easier 3D forming processes. As utilized herein, R 2 O includes Li 2 O, Na 2 O, K 2 O, Rb 2 O, Cs 2 O, and Fr 2 O. In embodiments, the sum of R 2 O and RO (i.e., R 2 O+RO) is greater than or equal to 18.0 mol %, such as greater than or equal to 18.5 mol %, greater than or equal to 19.0 mol %, greater than or equal to 19.5 mol %, greater than or equal to 20.0 mol %, greater than or equal to 20.5 mol %, greater than or equal to 21.0 mol %, greater than or equal to 21.5 mol %, greater than or equal to 22.0 mol %, greater than or equal to 22.5 mol %, or greater than or equal to 23.0 mol %. In embodiments, the sum of R 2 O and RO is less than or equal to 22.5 mol %, such as less than or equal to 22.0 mol %, less than or equal to 21.5 mol %, less than or equal to 21.0 mol %, less than or equal to 20.5 mol %, less than or equal to 20.0 mol %, less than or equal to 19.5 mol %, less than or equal to 19.0 mol %, or less than or equal to 18.5 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the sum of R 2 O and RO in the glass composition is from greater than or equal to 18.0 mol % to less than or equal to 23.0 mol %, such as from greater than or equal to 18.5 mol % to less than or equal to 22.5 mol %, from greater than or equal to 19.0 mol % to less than or equal to 22.0 mol %, from greater than or equal to 19.5 mol % to less than or equal to 21.5 mol %, or from greater than or equal to 20.0 mol % to less than or equal to 21.0 mol %, and all ranges and sub-ranges between the foregoing values. 
     In embodiments, a relationship, in mol %, of R 2 O/Al 2 O 3  is greater than or equal to 1.06. Having a ratio of R 2 O to Al 2 O 3  above 1.06 improves the meltability of the glass. One skilled in the art of glassmaking knows that R 2 O in excess of Al 2 O 3  greatly improves the dissolution of SiO 2  in a glass melt. This value is closely controlled in glass design to improve yields by reducing losses due to inclusions such as silica knots. In some embodiments, the molar ratio of R 2 O/Al 2 O 3  is greater than or equal to 1.10, such as greater than or equal to 1.20, greater than or equal to 1.30, greater than or equal to 1.40, greater than or equal to 1.50, greater than or equal to 1.60, greater than or equal to 1.70, greater than or equal to 1.80, greater than or equal to 1.90, or greater than or equal to 2.00. However, if the R 2 O/Al 2 O 3  ratio is too high, the glass may become susceptible to degradation. In embodiments, a molar ratio of R 2 O/Al 2 O 3  is less than or equal to 2.10, such as less than or equal to 2.00, less than or equal to 1.90, less than or equal to 1.80, less than or equal to 1.70, less than or equal to 1.60, less than or equal to 1.50, less than or equal to 1.40, less than or equal to 1.30, less than or equal to 1.20, or less than or equal to 1.10. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the molar ratio of R 2 O/Al 2 O 3  is from greater than or equal to 1.06 to less than or equal to 2.10, such as from greater than or equal to 1.10 to less than or equal to 1.90, from greater than or equal to 1.20 to less than or equal to 1.80, or from greater than or equal to 1.30 to less than or equal to 1.70, and all ranges and sub-ranges between the foregoing values. 
     In embodiments, the total amount of network forming components (e.g., Al 2 O 3 +SiO 2 +B 2 O 3 +P 2 O 5 ) is greater than or equal to 78.0 mol %, such as greater than or equal to 78.5 mol %, greater than or equal to 79.0 mol %, greater than or equal to 78.5 mol %, greater than or equal to 80.0 mol %, greater than or equal to 80.5 mol %, greater than or equal to 81.0 mol %, greater than or equal to 81.5 mol %, greater than or equal to 82.0 mol %, greater than or equal to 82.5 mol %, greater than or equal to 83.0 mol %, greater than or equal to 83.5 mol %, or greater than or equal to 84.0 mol %. Having a high amount of network forming components increases the connectivity and free volume of the glass, which makes it less brittle and improves the damage resistance. In embodiments, the total amount of network forming components is less than or equal to 85.0 mol %, such as less than or equal to 84.5 mol %, less than or equal to 84.0 mol %, less than or equal to 83.5 mol %, less than or equal to 83.0 mol %, less than or equal to 82.5 mol %, less than or equal to 82.0 mol %, less than or equal to 81.5 mol %, less than or equal to 81.0 mol %, less than or equal to 80.5 mol %, less than or equal to 80.0 mol %, less than or equal to 79.5 mol %, or less than or equal to 79.0 mol %. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the total amount of network forming components is from greater than or equal to 78.0 mol % to less than or equal to 85.0 mol %, such as greater than or equal to 78.0 mol % to less than or equal to 83.0 mol %, greater than or equal to 80.0 mol % to less than or equal to 82.0 mol %, or greater than or equal to 80.5 mol % to less than or equal to 81.5 mol %, and all ranges and sub-ranges between the foregoing values. 
     In one or more embodiments, the amount of glass network forming components, such as SiO 2 , Al 2 O 3 , B 2 O 3 , and P 2 O 5 , may be balanced against the amount of Li 2 O in the glass composition. Without being bound to any particular theory, it is believed that Li 2 O decreases the free volume in the glass relative to other alkali ions, thus reducing the indentation crack resistance. Since Li 2 O is needed for Na +  for Li + , ion-exchange, the free volume reducing Li 2 O should be managed relative to the free volume increasing network formers, i.e. SiO 2 , Al 2 O 3 , B 2 O 3 , and P 2 O 5  to retain suitable sharp contact damage resistance. Thus, in embodiments, the ratio, in mol %, of glass network formers to Li 2 O (i.e., (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O) is greater than or equal to 8.0, such as greater than or equal to 8.5, greater than or equal to 9.0, greater than or equal to 9.5, greater than or equal to 10.0, greater than or equal to 10.5, greater than or equal to 11.0, greater than or equal to 11.5, greater than or equal to 12.0, greater than or equal to 12.5, greater than or equal to 13.0, greater than or equal to 13.5, greater than or equal to 14.0, greater than or equal to 14.5, greater than or equal to 15.0, greater than or equal to 15.5, greater than or equal to 16.0, or greater than or equal to 16.5. In other embodiments the ratio (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is less than or equal to 17.0, such as less than or equal to 16.5, less than or equal to 16.0, less than or equal to 15.5, less than or equal to 15.0, less than or equal to 14.5, less than or equal to 14.0, less than or equal to 13.5, less than or equal to 13.0, less than or equal to 12.5, less than or equal to 12.0, less than or equal to 11.5, less than or equal to 11.0, less than or equal to 10.5, less than or equal to 10.0, less than or equal to 9.5, less than or equal to 9.0, or less than or equal to 8.5. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the ratio (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is from greater than or equal to 8.0 to less than or equal to 17.0, such as from greater than or equal to 9.0 to less than or equal to 16.0, from greater than or equal to 10.0 to less than or equal to 15.0, from greater than or equal to 11.0 to less than or equal to 14.0, or from greater than or equal to 12.0 to less than or equal to 13.0, and all ranges and sub-ranges between the foregoing values. 
     The sum of Al 2 O 3 +Li 2 O should be greater than or equal to 23.0 mol %, such as greater than or equal to 23.5 mol %, greater than or equal to 24.0 mol %, greater than or equal to 24.5 mol %, greater than or equal to 25.0 mol %, greater than or equal to 25.5 mol %, greater than or equal to 26.0 mol %, greater than or equal to 26.5 mol %, greater than or equal to 27.0 mol %, greater than or equal to 27.5 mol %, greater than or equal to 28.0 mol %, greater than or equal to 28.5 mol %, greater than or equal to 29.0 mol %, greater than or equal to 29.5 mol %, or greater than or equal to 30.0 mol %. The sum of Al 2 O 3 +Li 2 O should be as high as possible to promote maximum compressive stress at a given depth for the tail of the ion-exchange profile. 
     In embodiments, the glass article may be substantially free of one or both of arsenic and antimony. In other embodiments, the glass article may be free of one or both of arsenic and antimony. 
     Physical properties of the alkali aluminosilicate glass compositions as disclosed above will now be discussed. These physical properties can be achieved by modifying the component amounts of the alkali aluminosilicate glass composition, as will be discussed in more detail with reference to the examples. 
     Glass compositions according to embodiments may have a density from greater than or equal to 2.20 g/cm 3  to less than or equal to 2.60 g/cm 3 , such as from greater than or equal to 2.25 g/cm 3  to less than or equal to 2.60 g/cm 3 , from greater than or equal to 2.30 g/cm 3  to less than or equal to 2.60 g/cm 3 , from greater than or equal to 2.35 g/cm 3  to less than or equal to 2.60 g/cm 3 , from greater than or equal to 2.40 g/cm 3  to less than or equal to 2.60 g/cm 3 , or from greater than or equal to 2.45 g/cm 3  to less than or equal to 2.60 g/cm 3 . In embodiments, the glass composition may have a density from greater than or equal to 2.20 g/cm 3  to less than or equal to 2.45 g/cm 3 , such as from greater than or equal to 2.20 g/cm 3  to less than or equal to 2.40 g/cm 3 , from greater than or equal to 2.20 g/cm 3  to less than or equal to 2.35 g/cm 3 , from greater than or equal to 2.20 g/cm 3  to less than or equal to 2.30 g/cm 3 , or from greater than or equal to 2.20 g/cm 3  to less than or equal to 2.25 g/cm 3 , and all ranges and sub-ranges between the foregoing values. Generally, as larger, denser alkali metal cations, such as Na +  or K + , are replaced with smaller alkali metal cations, such as Li + , in an alkali aluminosilicate glass composition, the density of the glass composition decreases. Accordingly, the higher the amount of lithium in the glass composition, the less dense the glass composition will be. The density values recited in this disclosure refer to a value as measured by the buoyancy method of ASTM C693-93(2013). 
     In embodiments, the liquidus viscosity of the glass composition is less than or equal to 1000 kP, such as less than or equal to 800 kP, less than or equal to 600 kP, less than or equal to 400 kP, less than or equal to 200 kP, less than or equal to 100 kP, less than or equal to 75 kP, less than or equal to 60 kP, less than or equal to 50 kP, less than or equal to 40 kP, or less than or equal to 30 kP. In embodiments, the liquidus viscosity of the glass composition is greater than or equal to 20 kP, such as greater than or equal to 40 kP, greater than or equal to 60 kP, greater than or equal to 80 kP, greater than or equal to 100 kP, greater than or equal to 120 kP, greater than or equal to 140 kP, or greater than or equal to 160 kP. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the liquidus viscosity of the glass composition is from greater than or equal to 20 kP to less than or equal to 1000 kP, such as greater than or equal to 40 kP to less than or equal to 900 kP, greater than or equal to 60 kP to less than or equal to 800 kP, or greater than or equal to 80 kP to less than or equal to 700 kP, and all ranges and sub-ranges between the foregoing values. The liquidus viscosity is determined by the following method. First, the liquidus temperature of the glass is measured in accordance with ASTM C829-81 (2015), titled “Standard Practice for Measurement of Liquidus Temperature of Glass by the Gradient Furnace Method”. Next, the viscosity of the glass at the liquidus temperature is measured in accordance with ASTM C965-96(2012), titled “Standard Practice for Measuring Viscosity of Glass Above the Softening Point”. 
     The addition of lithium to the glass composition also affects the Young&#39;s modulus, shear modulus, and Poisson&#39;s ratio of the glass composition. In embodiments, the Young&#39;s modulus of the glass composition may be from greater than or equal to 65 GPa to less than or equal to 85 GPa, such as from greater than or equal to 67 GPa to less than or equal to 82 GPa, from greater than or equal to 70 GPa to less than or equal to 80 GPa, from greater than or equal to 72 GPa to less than or equal to 78 GPa, or from greater than or equal to 74 GPa to less than or equal to 76 GPa, and all ranges and sub-ranges between the foregoing values. In other embodiments, the Young&#39;s modulus of the glass composition may be from greater than or equal to 66 GPa to less than or equal to 85 GPa, such as from greater than or equal to 68 GPa to less than or equal to 85 GPa, from greater than or equal to 70 GPa to less than or equal to 85 GPa, from greater than or equal to 72 GPa to less than or equal to 85 GPa, from greater than or equal to 74 GPa to less than or equal to 85 GPa, from greater than or equal to 76 GPa to less than or equal to 85 GPa, from greater than or equal to 78 GPa to less than or equal to 85 GPa, from greater than or equal to 80 GPa to less than or equal to 85 GPa, or from greater than or equal to 82 GPa to less than or equal to 85 GPa, and all ranges and sub-ranges between the foregoing values. In embodiments, the Young&#39;s modulus may be from greater than or equal to 65 GPa to less than or equal to 84 GPa, such as from greater than or equal to 65 GPa to less than or equal to 82 GPa, from greater than or equal to 65 GPa to less than or equal to 80 GPa, from greater than or equal to 65 GPa to less than or equal to 78 GPa, from greater than or equal to 65 GPa to less than or equal to 76 GPa, from greater than or equal to 65 GPa to less than or equal to 74 GPa, from greater than or equal to 65 GPa to less than or equal to 72 GPa, from greater than or equal to 65 GPa to less than or equal to 70 GPa, from greater than or equal to 65 GPa to less than or equal to 68 GPa, or from greater than or equal to 65 GPa to less than or equal to 10 GPa, and all ranges and sub-ranges between the foregoing values. The Young&#39;s modulus values recited in this disclosure refer to a value as measured by a resonant ultrasonic spectroscopy technique of the general type set forth in ASTM E2001-13, titled “Standard Guide for Resonant Ultrasound Spectroscopy for Defect Detection in Both Metallic and Non-metallic Parts.” 
     The softening point of the glass composition is affected by the addition of lithium to the glass composition. According to one or more embodiments, the softening point of the glass composition may be from greater than or equal to 700° C. to less than or equal to 930° C., such as from greater than or equal to 705° C. to less than or equal to 925° C., from greater than or equal to 710° C. to less than or equal to 920° C., from greater than or equal to 715° C. to less than or equal to 915° C., from greater than or equal to 720° C. to less than or equal to 910° C., from greater than or equal to 725° C. to less than or equal to 905° C., from greater than or equal to 730° C. to less than or equal to 900° C., from greater than or equal to 735° C. to less than or equal to 895° C., from greater than or equal to 740° C. to less than or equal to 890° C., from greater than or equal to 745° C. to less than or equal to 885° C., from greater than or equal to 750° C. to less than or equal to 880° C., from greater than or equal to 755° C. to less than or equal to 875° C., from greater than or equal to 760° C. to less than or equal to 870° C., from greater than or equal to 765° C. to less than or equal to 865° C., from greater than or equal to 770° C. to less than or equal to 860° C., from greater than or equal to 775° C. to less than or equal to 855° C., from greater than or equal to 780° C. to less than or equal to 850° C., from greater than or equal to 785° C. to less than or equal to 845° C., from greater than or equal to 790° C. to less than or equal to 840° C., from greater than or equal to 795° C. to less than or equal to 835° C., from greater than or equal to 800° C. to less than or equal to 830° C., from greater than or equal to 805° C. to less than or equal to 825° C., or from greater than or equal to 810° C. to less than or equal to 820° C., and all ranges and sub-ranges between the foregoing values. The softening point was determined using the parallel plate viscosity method of ASTM C1351M-96(2012). 
     From the above, glass compositions according to embodiments may be formed by any suitable method, such as slot forming, float forming, rolling processes, fusion forming processes, etc. 
     The glass article may be characterized by the manner in which it is formed. For instance, the glass article may be characterized as float-formable (i.e., formed by a float process), down-drawable and, in particular, fusion-formable or slot-drawable (i.e., formed by a down draw process such as a fusion draw process or a slot draw process). 
     Some embodiments of the glass articles described herein may be formed by a down-draw process. Down-draw processes produce glass articles having a uniform thickness that possess relatively pristine surfaces. Because the average flexural strength of the glass article is controlled by the amount and size of surface flaws, a pristine surface that has had minimal contact has a higher initial strength. In addition, down drawn glass articles have a very flat, smooth surface that can be used in its final application without costly grinding and polishing. 
     Some embodiments of the glass articles may be described as fusion-formable (i.e., formable using a fusion draw process). The fusion process uses a drawing tank that has a channel for accepting molten glass raw material. The channel has weirs that are open at the top along the length of the channel on both sides of the channel. When the channel fills with molten material, the molten glass overflows the weirs. Due to gravity, the molten glass flows down the outside surfaces of the drawing tank as two flowing glass films. These outside surfaces of the drawing tank extend down and inwardly so that they join at an edge below the drawing tank. The two flowing glass films join at this edge to fuse and form a single flowing glass article. The fusion draw method offers the advantage that, because the two glass films flowing over the channel fuse together, neither of the outside surfaces of the resulting glass article comes in contact with any part of the apparatus. Thus, the surface properties of the fusion drawn glass article are not affected by such contact. 
     Some embodiments of the glass articles described herein may be formed by a slot draw process. The slot draw process is distinct from the fusion draw method. In slot draw processes, the molten raw material glass is provided to a drawing tank. The bottom of the drawing tank has an open slot with a nozzle that extends the length of the slot. The molten glass flows through the slot/nozzle and is drawn downward as a continuous glass article and into an annealing region. 
     In one or more embodiments, the glass articles described herein may exhibit an amorphous microstructure and may be substantially free of crystals or crystallites. In other words, the glass articles exclude glass-ceramic materials in some embodiments. 
     As mentioned above, in embodiments, the alkali aluminosilicate glass compositions can be strengthened, such as by ion exchange, making a glass that is damage resistant for applications such as, but not limited to, glass for display covers. With reference to  FIG.  1   , the glass has a first region under compressive stress (e.g., first and second compressive layers  120 ,  122  in  FIG.  1   ) extending from the surface to a depth of compression (DOC) of the glass and a second region (e.g., central region  130  in  FIG.  1   ) under a tensile stress or central tension (CT) extending from the DOC into the central or interior region of the glass. As used herein, DOC refers to the depth at which the stress within the glass article changes from compressive to tensile. At the DOC, the stress crosses from a positive (compressive) stress to a negative (tensile) stress and thus exhibits a stress value of zero. 
     According to the convention normally used in the art, compression or compressive stress is expressed as a negative (&lt;0) stress and tension or tensile stress is expressed as a positive (&gt;0) stress. Throughout this description, however, CS is expressed as a positive or absolute value—i.e., as recited herein, CS=|CS|. The compressive stress (CS) has a maximum at or near the surface of the glass, and the CS varies with distance d from the surface according to a function. Referring again to  FIG.  1   , a first segment  120  extends from first surface  110  to a depth d 1  and a second segment  122  extends from second surface  112  to a depth dz. Together, these segments define a compression or CS of glass  100 . Compressive stress (including surface CS) is measured by surface stress meter (FSM) using commercially available instruments such as the FSM-6000, manufactured by Orihara Industrial Co., Ltd. (Japan). Surface stress measurements rely upon the accurate measurement of the stress optical coefficient (SOC), which is related to the birefringence of the glass. SOC in turn is measured according to Procedure C (Glass Disc Method) described in ASTM standard C770-16, entitled “Standard Test Method for Measurement of Glass Stress-Optical Coefficient,” the contents of which are incorporated herein by reference in their entirety. 
     In some embodiments, the CS is from greater than or equal to 450 MPa to less than or equal to 800 MPa, such as from greater than or equal to 475 MPa to less than or equal to 775 MPa, from greater than or equal to 500 MPa to less than or equal to 750 MPa, from greater than or equal to 525 MPa to less than or equal to 725 MPa, from greater than or equal to 550 MPa to less than or equal to 700 MPa, from greater than or equal to 575 MPa to less than or equal to 675 MPa, or from greater than or equal to 600 MPa to less than or equal to 650 MPa, and all ranges and sub-ranges between the foregoing values. 
     In one or more embodiments, Na +  and K +  ions are exchanged into the glass article and the Na +  ions diffuse to a deeper depth into the glass article than the K +  ions. The depth of penetration of K +  ions (“Potassium DOL”) is distinguished from DOC because it represents the depth of potassium penetration as a result of an ion exchange process. The Potassium DOL is typically less than the DOC for the articles described herein. Potassium DOL is measured using a surface stress meter such as the commercially available FSM-6000 surface stress meter, manufactured by Orihara Industrial Co., Ltd. (Japan), which relies on accurate measurement of the stress optical coefficient (SOC), as described above with reference to the CS measurement. The Potassium DOL of each of first and second compressive layers  120 ,  122  is from greater than or equal to 5 μm to less than or equal to 45 μm, such as from greater than or equal to 6 μm to less than or equal to 40 μm, from greater than or equal to 7 μm to less than or equal to 35 μm, from greater than or equal to 8 μm to less than or equal to 30 μm, or from greater than or equal to 9 μm to less than or equal to 25 μm, and all ranges and sub-ranges between the foregoing values. In embodiments, the Potassium DOL of each of the first and second compressive layers  120 ,  122  is from greater than or equal to 6 μm to less than or equal to 45 μm, from greater than or equal to 10 μm to less than or equal to 45 μm, from greater than or equal to 15 μm to less than or equal to 45 μm, from greater than or equal to 20 μm to less than or equal to 45 μm, or from greater than or equal to 25 μm to less than or equal to 45 μm, and all ranges and sub-ranges between the foregoing values. In embodiments, the Potassium DOL of each of the first and second compressive layers  120 ,  122  is from greater than or equal to 5 μm to less than or equal to 35 μm, from greater than or equal to 5 μm to less than or equal to 30 μm, from greater than or equal to 5 μm to less than or equal to 25 μm, or from greater than or equal to 5 μm to less than or equal to 15 μm, and all ranges and sub-ranges between the foregoing values. 
     The compressive stress of both major surfaces ( 110 ,  112  in  FIG.  1   ) is balanced by stored tension in the central region ( 130 ) of the glass. The maximum central tension (CT) and DOC values are measured using a scattered light polariscope (SCALP) technique known in the art. The Refracted near-field (RNF) method or SCALP may be used to measure the stress profile. When the RNF method is utilized to measure the stress profile, the maximum CT value provided by SCALP is utilized in the RNF method. In particular, the stress profile measured by RNF is force balanced and calibrated to the maximum CT value provided by a SCALP measurement. The RNF method is described in U.S. Pat. No. 8,854,623, entitled “Systems and methods for measuring a profile characteristic of a glass sample”, which is incorporated herein by reference in its entirety. In particular, the RNF method includes placing the glass article adjacent to a reference block, generating a polarization-switched light beam that is switched between orthogonal polarizations at a rate of between 1 Hz and 50 Hz, measuring an amount of power in the polarization-switched light beam and generating a polarization-switched reference signal, wherein the measured amounts of power in each of the orthogonal polarizations are within 50% of each other. The method further includes transmitting the polarization-switched light beam through the glass sample and reference block for different depths into the glass sample, then relaying the transmitted polarization-switched light beam to a signal photodetector using a relay optical system, with the signal photodetector generating a polarization-switched detector signal. The method also includes dividing the detector signal by the reference signal to form a normalized detector signal and determining the profile characteristic of the glass sample from the normalized detector signal. 
     In embodiments, the glass composition may have a maximum CT greater than or equal to 30 MPa, such as greater than or equal to 35 MPa, greater than or equal to 40 MPa, greater than or equal to 45 MPa, greater than or equal to 50 MPa, greater than or equal to 55 MPa, greater than or equal to 60 MPa, greater than or equal to 65 MPa, greater than or equal to 70 MPa, greater than or equal to 75 MPa, greater than or equal to 80 MPa, or greater than or equal to 85 MPa. In embodiments, the glass composition may have a maximum CT less than or equal to 100 MPa, such as less than or equal to 95 MPa, less than or equal to 90 MPa, less than or equal to 85 MPa, less than or equal to 80 MPa, less than or equal to 75 MPa, less than or equal to 70 MPa, less than or equal to 65 MPa, less than or equal to 60 MPa, less than or equal to 55 MPa, less than or equal to 50 MPa, less than or equal to 45 MPa, or less than or equal to 40 MPa. It should be understood that, in embodiments, any of the above ranges may be combined with any other range. In embodiments, the glass composition may have a maximum CT from greater than or equal to 30 MPa to less than or equal to 100 MPa, such as from greater than or equal to 35 MPa to less than or equal to 95 MPa, from greater than or equal to 40 MPa to less than or equal to 90 MPa, from greater than or equal to 45 MPa to less than or equal to 85 MPa, from greater than or equal to 50 MPa to less than or equal to 80 MPa, from greater than or equal to 55 MPa to less than or equal to 75 MPa, or from greater than or equal to 60 MPa to less than or equal to 70 MPa, and all ranges and sub-ranges between the foregoing values. 
     As noted above, DOC is measured using a scattered light polariscope (SCALP) technique known in the art. The DOC is provided in some embodiments herein as a portion of the thickness (t) of the glass article. In embodiments, the glass compositions may have a depth of compression (DOC) from greater than or equal to 0.15t to less than or equal to 0.25t, such as from greater than or equal to 0.18t to less than or equal to 0.22t, or from greater than or equal to 0.19t to less than or equal to 0.21t, and all ranges and sub-ranges between the foregoing values. In embodiments, the glass composition may have a DOC from greater than or equal to 0.16t to less than or equal to 0.20t, such as from greater than or equal to 0.17t to less than or equal to 0.25t, from greater than or equal to 0.18t to less than or equal to 0.25t, from greater than or equal to 0.19t to less than or equal to 0.25t, from greater than or equal to 0.20t to less than or equal to 0.25t, from greater than or equal to 0.21t to less than or equal to 0.25t, from greater than or equal to 0.22t to less than or equal to 0.25t, from greater than or equal to 0.23t to less than or equal to 0.25t, or from greater than or equal to 0.24t to less than or equal to 0.25t, and all ranges and sub-ranges between the foregoing values. In embodiments, the glass composition may have a DOC from greater than or equal to 0.15t to less than or equal to 0.24t, such as from greater than or equal to 0.15t to less than or equal to 0.23t, from greater than or equal to 0.15t to less than or equal to 0.22t, from greater than or equal to 0.15t to less than or equal to 0.21t, from greater than or equal to 0.15t to less than or equal to 0.20t, from greater than or equal to 0.15t to less than or equal to 0.19t, from greater than or equal to 0.15t to less than or equal to 0.18t, from greater than or equal to 0.15t to less than or equal to 0.17t, or from greater than or equal to 0.15t to less than or equal to 0.16t, and all ranges and sub-ranges between the foregoing values. 
     Compressive stress layers may be formed in the glass by exposing the glass to an ion exchange solution. In embodiments, the ion exchange solution may be molten nitrate salt. In embodiments, the ion exchange solution may be molten KNO 3 , molten NaNO 3 , or combinations thereof. In embodiments, the ion exchange solution may comprise about 80% molten KNO 3 , about 75% molten KNO 3 , about 70% molten KNO 3 , about 65% molten KNO 3 , or about 60% molten KNO 3 . In embodiments, the ion exchange solution may comprise about 20% molten NaNO 3 , about 25% molten NaNO 3 , about 30% molten NaNO 3 , about 35% molten NaNO 3 , or about 40% molten NaNO 3 . In embodiments, the ion exchange solution may comprise about 80% molten KNO 3  and about 20% molten NaNO 3 , about 75% molten KNO 3  and about 25% molten NaNO 3 , about 70% molten KNO 3  and about 30% molten NaNO 3 , about 65% molten KNO 3  and about 35% molten NaNO 3 , or about 60% molten KNO 3  and about 40% molten NaNO 3 , and all ranges and sub-ranges between the foregoing values. In embodiments, other sodium and potassium salts may be used in the ion exchange solution, such as, for example sodium or potassium nitrites, phosphates, or sulfates. In some embodiments, the ion exchange solution may include lithium salts, such as LiNO 3 . 
     The glass composition may be exposed to the ion exchange solution by dipping a glass article made from the glass composition into a bath of the ion exchange solution, spraying the ion exchange solution onto a glass article made from the glass composition, or otherwise physically applying the ion exchange solution to a glass article made from the glass composition. Upon exposure to the glass composition, the ion exchange solution may, according to embodiments, be at a temperature from greater than or equal to 400° C. to less than or equal to 500° C., such as from greater than or equal to 410° C. to less than or equal to 490° C., from greater than or equal to 420° C. to less than or equal to 480° C., from greater than or equal to 430° C. to less than or equal to 470° C., or from greater than or equal to 440° C. to less than or equal to 460° C., and all ranges and sub-ranges between the foregoing values. In embodiments, the glass composition may be exposed to the ion exchange solution for a duration from greater than or equal to 4 hours to less than or equal to 48 hours, such as from greater than or equal to 8 hours to less than or equal to 44 hours, from greater than or equal to 12 hours to less than or equal to 40 hours, from greater than or equal to 16 hours to less than or equal to 36 hours, from greater than or equal to 20 hours to less than or equal to 32 hours, or from greater than or equal to 24 hours to less than or equal to 28 hours, and all ranges and sub-ranges between the foregoing values. 
     The ion exchange process may be performed in an ion exchange solution under processing conditions that provide an improved compressive stress profile as disclosed, for example, in U.S. Patent Application Publication No. 2016/0102011, which is incorporated herein by reference in its entirety. 
     After an ion exchange process is performed, it should be understood that a composition at the surface of a glass article may be different than the composition of the as-formed glass article (i.e., the glass article before it undergoes an ion exchange process). This results from one type of alkali metal ion in the as-formed glass, such as, for example Li +  or Na + , being replaced with larger alkali metal ions, such as, for example Na +  or K + , respectively. However, the glass composition at or near the center of the depth of the glass article will, in embodiments, still have the composition of the as-formed (non-ion exchanged) glass utilized to form the glass article. 
     The glass articles disclosed herein may be incorporated into another article such as an article with a display (or display articles) (e.g., consumer electronics, including mobile phones, tablets, computers, navigation systems, and the like), architectural articles, transportation articles (e.g., automobiles, trains, aircraft, sea craft, etc.), appliance articles, or any article that requires some transparency, scratch-resistance, abrasion resistance or a combination thereof. An exemplary article incorporating any of the glass articles disclosed herein is shown in  FIGS.  2 A and  2 B . Specifically,  FIGS.  2 A and  2 B  show a consumer electronic device  200  including a housing  202  having front  204 , back  206 , and side surfaces  208 ; electrical components (not shown) that are at least partially inside or entirely within the housing and including at least a controller, a memory, and a display  210  at or adjacent to the front surface of the housing; and a cover substrate  212  at or over the front surface of the housing such that it is over the display. In some embodiments, a portion of the cover substrate  212  and/or a portion of housing  202  may include any of the glass articles disclosed herein. 
     A first clause comprises a glass composition comprising: from greater than or equal to 55.0 mol % to less than or equal to 75.0 mol % SiO 2 ; from greater than or equal to 8.0 mol % to less than or equal to 20.0 mol % Al 2 O 3 ; from greater than or equal to 3.0 mol % to less than or equal to 15.0 mol % Li 2 O; from greater than or equal to 5.0 mol % to less than or equal to 15.0 mol % Na 2 O; and less than or equal to 1.5 mol % K 2 O, wherein Al 2 O 3 +Li 2 O is greater than 22.5 mol %, R 2 O+RO is greater than or equal to 18.0 mol %, R 2 O/Al 2 O 3  is greater than or equal to 1.06, SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5  is greater than or equal to 78.0 mol %, and (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is greater than or equal to 8.0. 
     A second clause comprises a glass composition according to the first clause, wherein Al 2 O 3 +Li 2 O is greater than or equal to 23.0 mol %. 
     A third clause comprises a glass composition according to any one of the first and second clauses, wherein Al 2 O 3 +Li 2 O is from greater than or equal to 23.0 mol % to less than or equal to 26.5 mol %. 
     A fourth clause comprises a glass composition according to any one of the first to third clauses, wherein R 2 O+RO is from greater than or equal to 18.0 mol % to less than or equal to 23.0 mol %. 
     A fifth clause comprises a glass composition according to any one of the first to fourth clauses, wherein R 2 O+RO is from greater than or equal to 19.0 mol % to less than or equal to 22.0 mol %. 
     A sixth clause comprises a glass composition according to any one of the first to fifth clauses, wherein R 2 O/Al 2 O 3  is from greater than or equal to 1.06 to less than or equal to 2.10. 
     A seventh clause comprises a glass composition according to any one of the first to sixth clauses, wherein R 2 O/Al 2 O 3  is from greater than or equal to 1.10 to less than or equal to 1.90. 
     An eighth clause comprises a glass composition according to any one of the first to seventh clauses, wherein SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5  is from greater than or equal to 78.0 mol % to less than or equal to 85.0 mol %. 
     A ninth clause comprises a glass composition according to any one of the first to eighth clauses, wherein SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5  is from greater than or equal to 78.0 mol % to less than or equal to 83.0 mol %. 
     A tenth clause comprises a glass composition according to any one of the first to ninth clauses, wherein (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is from greater than or equal to 8.0 to less than or equal to 17.0. 
     An eleventh clause comprises a glass composition according to any one of the first to tenth clauses, wherein (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is from greater than or equal to 10.0 to less than or equal to 15.0. 
     A twelfth clause comprises a glass composition according to any one of the first to eleventh clauses, wherein B 2 O 3 +P 2 O 5  is greater than 0.0 mol %. 
     A thirteenth clause comprises a glass article comprising: a first surface; a second surface opposite the first surface, wherein a thickness (t) of the glass article is measured as a distance between the first surface and the second surface; and a compressive stress layer extending from at least one of the first surface and the second surface into the thickness (t) of the glass article, wherein a central tension of the glass article is greater than or equal to 30 MPa, the compressive stress layer has a depth of compression that is from greater than or equal to 0.15t to less than or equal to 0.25t, and the glass article is formed from a glass comprising: from greater than or equal to 55.0 mol % to less than or equal to 75.0 mol % SiO 2 ; from greater than or equal to 8.0 mol % to less than or equal to 20.0 mol % Al 2 O 3 ; from greater than or equal to 3.0 mol % to less than or equal to 15.0 mol % Li 2 O; from greater than or equal to 5.0 mol % to less than or equal to 15.0 mol % Na 2 O; and less than or equal to 1.5 mol % K 2 O, wherein Al 2 O 3 +Li 2 O is greater than 22.5 mol %, R 2 O+RO is greater than or equal to 18.0 mol %, R 2 O/Al 2 O 3  is greater than or equal to 1.06, SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5  is greater than or equal to 78.0 mol %, and (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is greater than or equal to 8.0. 
     A fourteenth clause comprises a glass article according to the thirteenth clause, wherein the central tension of the glass article is greater than or equal to 50 MPa. 
     A fifteenth clause comprises a glass article of any one of the thirteenth and fourteenth clauses, wherein the central tension of the glass article is greater than or equal to 80 MPa. 
     A sixteenth clause comprises a glass article according to any one of the thirteenth to fifteenth clauses, wherein a potassium depth of layer of the compressive stress layer into the thickness of the glass article is from greater than 5 μm to less than or equal to 45 μm. 
     A seventeenth clause comprises a glass article according to any one of the thirteenth to sixteenth clauses, wherein the glass has a liquidus viscosity from greater than or equal to 20 kP to less than 1000 kP. 
     An eighteenth clause comprises a glass article according to any one of the thirteenth to seventeenth clauses, wherein a surface compressive stress of the compressive stress layer is greater than or equal to 450 MPa to less than or equal to 800 MPa. 
     A nineteenth clause comprises a consumer electronic product, comprising: a housing comprising a front surface, a back surface and side surfaces; electrical components at least partially within the housing, the electrical components comprising at least a controller, a memory, and a display, the display at or adjacent the front surface of the housing; and a cover substrate disposed over the display, wherein at least a portion of at least one of the housing and the cover substrate comprises the a glass article according to any one of the thirteenth through eighteenth clauses. 
     A twentieth clause comprises a glass article comprising: a first surface; a second surface opposite the first surface, wherein a thickness (t) of the glass article is measured as a distance between the first surface and the second surface; and a compressive stress layer extending from at least one of the first surface and the second surface into the thickness (t) of the glass article, wherein a central tension of the glass article is greater than or equal to 60 MPa, the compressive stress layer has a depth of compression that is from greater than or equal to 0.15t to less than or equal to 0.25t, and the glass article has a composition at a center depth of the glass article comprising: from greater than or equal to 55.0 mol % to less than or equal to 75.0 mol % SiO 2 ; from greater than or equal to 8.0 mol % to less than or equal to 20.0 mol % Al 2 O 3 ; from greater than or equal to 3.0 mol % to less than or equal to 15.0 mol % Li 2 O; from greater than or equal to 5.0 mol % to less than or equal to 15.0 mol % Na 2 O; and less than or equal to 1.5 mol % K 2 O, wherein Al 2 O 3 +Li 2 O is greater than 22.5 mol %, R 2 O+RO is greater than or equal to 18.0 mol %, R 2 O/Al 2 O 3  is greater than or equal to 1.06, SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5  is greater than or equal to 78.0 mol %, and (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is greater than or equal to 8.0. 
     A twenty first clause comprises a glass composition comprising: from greater than or equal to 55.0 mol % to less than or equal to 70.0 mol % SiO 2 ; from greater than or equal to 10.0 mol % to less than or equal to 20.0 mol % Al 2 O 3 ; from greater than or equal to 3.0 mol % to less than or equal to 15.0 mol % Li 2 O; from greater than or equal to 5.0 mol % to less than or equal to 15.0 mol % Na 2 O; and less than or equal to 1.5 mol % K 2 O, wherein Al 2 O 3 +Li 2 O is greater than 22.5 mol %, R 2 O+RO is greater than or equal to 18.0 mol %, SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5  is greater than or equal to 78.0 mol %, and (SiO 2 +Al 2 O 3 +B 2 O 3 +P 2 O 5 )/Li 2 O is greater than or equal to 10.50. 
     A twenty second clause comprises a glass article comprising: a first surface; a second surface opposite the first surface, wherein a thickness (t) of the glass article is measured as a distance between the first surface and the second surface; and a compressive stress layer extending from at least one of the first surface and the second surface into the thickness (t) of the glass article, wherein a central tension of the glass article is greater than or equal to 30 MPa, the compressive stress layer has a depth of compression that is from greater than or equal to 0.15t to less than or equal to 0.25t, and the glass article is formed from a glass according to the twenty first clause. 
     A twenty third clause comprises the glass article of the twenty second clause, wherein the central tension of the glass article is greater than or equal to 50 MPa. 
     A twenty fourth clause comprises the glass article of any one of the twenty second and twenty third clauses, wherein the central tension of the glass article is greater than or equal to 80 MPa. 
     A twenty fifth clause comprises the glass article of any one of the twenty second to twenty fourth clauses, wherein a potassium depth of layer of the compressive stress layer into the thickness of the glass article is from greater than 5 μm to less than or equal to 45 μm. 
     A twenty sixth clause comprises the glass article of any one of the twenty second to twenty fifth, wherein the glass has a liquidus viscosity from greater than or equal to 20 kP to less than 1000 kP. 
     A twenty seventh clause comprises the glass article of any one of the twenty second to twenty sixth clauses, wherein a surface compressive stress of the compressive stress layer is greater than or equal to 450 MPa to less than or equal to 800 MPa. 
     A twenty eighth clause comprises a consumer electronic product, comprising: a housing comprising a front surface, a back surface and side surfaces; electrical components at least partially within the housing, the electrical components comprising at least a controller, a memory, and a display, the display at or adjacent the front surface of the housing; and a cover substrate disposed over the display, wherein at least a portion of at least one of the housing and the cover substrate comprises the glass article of anyone of the twenty second to twenty seventh clauses. 
     Examples 
     Embodiments will be further clarified by the following examples. It should be understood that these examples are not limiting to the embodiments described above. 
     Glass compositions having components listed in Table 1 below were prepared by conventional glass forming methods. In Table 1, all components are in mol %, and various properties of the glass compositions were measured according to the methods disclosed in this specification. 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                 Sample 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 10 
               
               
                   
               
               
                 SiO 2   
                 64.35 
                 63.38 
                 62.28 
                 61.30 
                 60.28 
                 59.35 
                 64.52 
                 63.36 
                 62.47 
                 61.40 
               
               
                 Al 2 O 3   
                 16.33 
                 16.26 
                 16.30 
                 16.32 
                 16.36 
                 16.34 
                 16.16 
                 16.32 
                 16.21 
                 16.30 
               
               
                 P 2 O 5   
                 0.00 
                 0.96 
                 1.94 
                 2.93 
                 3.91 
                 4.86 
                 0.00 
                 0.98 
                 1.91 
                 2.93 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 7.19 
                 7.27 
                 7.35 
                 7.39 
                 7.39 
                 7.39 
                 7.53 
                 7.71 
                 7.79 
                 7.83 
               
               
                 Na 2 O 
                 12.05 
                 12.05 
                 12.05 
                 11.99 
                 11.97 
                 11.99 
                 11.70 
                 11.53 
                 11.54 
                 11.46 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
               
               
                 ZnO 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 23.52 
                 23.53 
                 23.65 
                 23.71 
                 23.75 
                 23.72 
                 23.69 
                 24.04 
                 24.00 
                 24.13 
               
               
                 R 2 O 
                 19.25 
                 19.33 
                 19.41 
                 19.39 
                 19.37 
                 19.39 
                 19.25 
                 19.26 
                 19.34 
                 19.30 
               
               
                 R 2 O + RO 
                 19.27 
                 19.35 
                 19.43 
                 19.40 
                 19.40 
                 19.41 
                 19.27 
                 19.28 
                 19.36 
                 19.32 
               
               
                 Li 2 O/Na 2 O 
                 0.60 
                 0.60 
                 0.61 
                 0.62 
                 0.62 
                 0.62 
                 0.64 
                 0.67 
                 0.67 
                 0.68 
               
               
                 SiO 2  + Al 2 O 3   
                 80.68 
                 79.64 
                 78.58 
                 77.62 
                 76.64 
                 75.68 
                 80.68 
                 79.69 
                 78.68 
                 77.70 
               
               
                 R 2 O/Al 2 O 3   
                 1.18 
                 1.19 
                 1.19 
                 1.19 
                 1.18 
                 1.19 
                 1.19 
                 1.18 
                 1.19 
                 1.18 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 80.68 
                 80.60 
                 80.52 
                 80.55 
                 80.55 
                 80.54 
                 80.68 
                 80.67 
                 80.59 
                 80.63 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 11.22 
                 11.09 
                 10.96 
                 10.90 
                 10.90 
                 10.90 
                 10.71 
                 10.46 
                 10.35 
                 10.29 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.438 
                 2.433 
                 2.428 
                 2.423 
                 2.419 
                 2.414 
                 2.439 
                 2.432 
                 2.427 
                 2.423 
               
               
                 Strain Pt. (° C.) 
                 542 
                 555 
                 564 
                 565 
                 561 
                 548 
                 538 
                 555 
                 564 
                 566 
               
               
                 Anneal Pt. (° C.) 
                 591 
                 605 
                 614 
                 615 
                 611 
                 598 
                 586 
                 605 
                 615 
                 616 
               
               
                 Softening Pt. (° C.) 
                 836.2 
                 848.6 
                 854.7 
                 858.6 
                 854 
                 849.3 
                 826.2 
                 845.1 
                 854.7 
                 854.2 
               
               
                 10 11  Poise Temperature 
                 674 
                 689 
                 697 
                 699 
                 694 
                 683 
                 667 
                 688 
                 699 
                 699 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 84.8 
                 85.7 
                 86.5 
                 86 
                 86.5 
                 86.2 
                 84.3 
                 85 
                 84.6 
                 85 
               
               
                 Fulchers A 
                 −3.789 
                 −3.451 
                 −3.171 
                 −3.43 
                 −2.873 
                 −3.055 
                 −3.478 
                 −3.497 
                 −3.161 
                 −3.083 
               
               
                 Fulchers B 
                 10641.6 
                 9417.5 
                 8603.9 
                 9096 
                 7750.1 
                 8143.9 
                 9775.3 
                 9535.6 
                 8556.3 
                 8276.4 
               
               
                 Fulchers To 
                 −124.5 
                 −21.8 
                 44.9 
                 18.3 
                 107.4 
                 78.2 
                 −75.3 
                 −28 
                 45.1 
                 71.1 
               
               
                 200 P Temperature (° C.) 
                 1623 
                 1615 
                 1617 
                 1605 
                 1605 
                 1599 
                 1616 
                 1617 
                 1612 
                 1608 
               
               
                  35000 P Temperature  
                 1153 
                 1156 
                 1160 
                 1159 
                 1152 
                 1150 
                 1143 
                 1158 
                 1156 
                 1156 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1046 
                 1054 
                 1060 
                 1060 
                 1056 
                 1053 
                 1038 
                 1056 
                 1056 
                 1058 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 575 
                 526 
                 957 
                 1067 
                 1020 
                 2190 
                 452 
                 328 
                 458 
                 540 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.88 
                 2.908 
                 2.92 
                 2.917 
                 2.959 
                 2.927 
                 2.882 
                 2.883 
                 2.91 
                 2.911 
               
               
                 Refractive Index 
                 1.5114 
                 1.5094 
                 1.5073 
                 1.5055 
                 1.5036 
                 1.5029 
                 1.5119 
                 1.5098 
                 1.5077 
                 1.506 
               
               
                 Young&#39;s Modulus (GPa) 
                 79.6 
                 78.2 
                 77.4 
                 76.1 
                 74.6 
                 73.7 
                 80.2 
                 78.9 
                 77.3 
                 76.3 
               
               
                   
               
               
                 Sample 
                 11 
                 12 
                 13 
                 14 
                 15 
                 16 
                 17 
                 18 
                 19 
                 20 
               
               
                   
               
               
                 SiO 2   
                 60.29 
                 59.46 
                 64.31 
                 63.32 
                 62.48 
                 61.36 
                 60.29 
                 59.43 
                 59.89 
                 60.39 
               
               
                 Al 2 O 3   
                 16.31 
                 16.25 
                 16.19 
                 16.30 
                 16.19 
                 16.33 
                 16.36 
                 16.32 
                 16.31 
                 16.26 
               
               
                 P 2 O 5   
                 3.93 
                 4.84 
                 0.00 
                 0.97 
                 1.99 
                 2.92 
                 3.97 
                 4.91 
                 4.91 
                 4.90 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 7.92 
                 7.95 
                 8.12 
                 8.21 
                 8.21 
                 8.31 
                 8.33 
                 8.33 
                 8.35 
                 8.42 
               
               
                 Na 2 O 
                 11.48 
                 11.42 
                 11.30 
                 11.12 
                 11.05 
                 11.00 
                 10.97 
                 10.94 
                 10.46 
                 9.95 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
               
               
                 ZnO 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 24.22 
                 24.20 
                 24.31 
                 24.51 
                 24.40 
                 24.64 
                 24.69 
                 24.65 
                 24.65 
                 24.69 
               
               
                 R 2 O 
                 19.40 
                 19.37 
                 19.42 
                 19.34 
                 19.26 
                 19.31 
                 19.31 
                 19.28 
                 18.82 
                 18.38 
               
               
                 R 2 O + RO 
                 19.42 
                 19.39 
                 19.44 
                 19.36 
                 19.28 
                 19.33 
                 19.33 
                 19.30 
                 18.84 
                 18.40 
               
               
                 Li 2 O/Na 2 O 
                 0.69 
                 0.70 
                 0.72 
                 0.74 
                 0.74 
                 0.76 
                 0.76 
                 0.76 
                 0.80 
                 0.85 
               
               
                 SiO 2  + Al 2 O 3   
                 76.60 
                 75.71 
                 80.51 
                 79.62 
                 78.68 
                 77.69 
                 76.65 
                 75.75 
                 76.20 
                 76.66 
               
               
                 R 2 O/Al 2 O 3   
                 1.19 
                 1.19 
                 1.20 
                 1.19 
                 1.19 
                 1.18 
                 1.18 
                 1.18 
                 1.15 
                 1.13 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 80.53 
                 80.56 
                 80.51 
                 80.59 
                 80.67 
                 80.62 
                 80.62 
                 80.65 
                 81.11 
                 81.55 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 10.17 
                 10.13 
                 9.92 
                 9.81 
                 9.83 
                 9.70 
                 9.68 
                 9.68 
                 9.72 
                 9.68 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.418 
                 2.414 
                 2.437 
                 2.429 
                 2.425 
                 2.42 
                 2.417 
                 2.413 
                 2.409 
                 2.404 
               
               
                 Strain Pt. (° C.) 
                 561 
                 555 
                 531 
                 554 
                 560 
                 565 
                 561 
                 552 
                 553 
                 557 
               
               
                 Anneal Pt. (° C.) 
                 610 
                 605 
                 579 
                 602 
                 610 
                 614 
                 611 
                 602 
                 602 
                 607 
               
               
                 Softening Pt. (° C.) 
                 851.5 
                 849.5 
                 815.1 
                 842.5 
                 846.5 
                 855 
                 850.6 
                 843.3 
                 847 
                 853 
               
               
                 10 11  Poise Temperature 
                 692 
                 689 
                 660 
                 683 
                 692 
                 696 
                 694 
                 685 
                 685 
                 691 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 86 
                 85.8 
                 84.3 
                 84.1 
                 84.2 
                 84.9 
                 85.4 
                 85.1 
                 82.7 
                 81.4 
               
               
                 Fulchers A 
                 −3.564 
                 −3.164 
                 −3.476 
                 −3.824 
                 −3.254 
                 −2.999 
                 −3.349 
                 −3.189 
                 −2.854 
                 −3.191 
               
               
                 Fulchers B 
                 9520.9 
                 8372.3 
                 9779.2 
                 10717.7 
                 8803.7 
                 8062.7 
                 8831 
                 8366.6 
                 7673 
                 8433.7 
               
               
                 Fulchers To 
                 −45.9 
                 58 
                 −93.3 
                 −150.9 
                 7.6 
                 83.2 
                 27.2 
                 57.3 
                 105.4 
                 67.4 
               
               
                 200 P Temperature (° C.) 
                 1577 
                 1590 
                 1599 
                 1599 
                 1592 
                 1604 
                 1590 
                 1581 
                 1594 
                 1603 
               
               
                  35000 P Temperature  
                 1128 
                 1144 
                 1126 
                 1130 
                 1137 
                 1152 
                 1146 
                 1139 
                 1143 
                 1158 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1028 
                 1047 
                 1021 
                 1024 
                 1037 
                 1055 
                 1048 
                 1043 
                 1046 
                 1061 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 424 
                 1312 
                 223 
                 179 
                 206 
                 405 
                 536 
                 756 
                 474 
                 512 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.906 
                 2.919 
                 2.865 
                 2.892 
                 2.912 
                 2.922 
                 2.931 
                 2.941 
                 2.935 
                 2.966 
               
               
                 Refractive Index 
                 1.5041 
                 1.5026 
                 1.5126 
                 1.5101 
                 1.5081 
                 1.5063 
                 1.5048 
                 1.5033 
                 1.5028 
                 1.5021 
               
               
                 Young&#39;s Modulus (GPa) 
                 75.1 
                 74.1 
                 80.4 
                 79.2 
                 78.1 
                 76.7 
                 75.8 
                 74.6 
                 74.0 
                 74.6 
               
               
                   
               
               
                 Sample 
                 21 
                 22 
                 23 
                 24 
                 25 
                 26 
                 27 
                 28 
                 29 
                 30 
               
               
                   
               
               
                 SiO 2   
                 59.90 
                 60.19 
                 59.84 
                 60.10 
                 61.40 
                 61.36 
                 61.32 
                 61.37 
                 61.39 
                 61.45 
               
               
                 Al 2 O 3   
                 16.31 
                 16.38 
                 16.40 
                 16.45 
                 16.25 
                 16.30 
                 16.33 
                 16.29 
                 16.25 
                 16.29 
               
               
                 P 2 O 5   
                 4.91 
                 4.94 
                 4.95 
                 4.99 
                 2.91 
                 2.92 
                 2.91 
                 2.92 
                 2.92 
                 2.89 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 8.84 
                 8.95 
                 9.24 
                 9.37 
                 8.38 
                 8.41 
                 8.37 
                 8.34 
                 8.39 
                 8.38 
               
               
                 Na 2 O 
                 9.95 
                 9.46 
                 9.49 
                 9.00 
                 9.99 
                 9.99 
                 10.07 
                 9.02 
                 9.05 
                 9.00 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 1.01 
                 0.02 
                 0.49 
                 2.00 
                 0.02 
                 1.00 
               
               
                 ZnO 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.94 
                 0.46 
                 0.00 
                 1.92 
                 0.93 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 25.15 
                 25.34 
                 25.63 
                 25.82 
                 24.63 
                 24.71 
                 24.69 
                 24.64 
                 24.64 
                 24.66 
               
               
                 R 2 O 
                 18.80 
                 18.42 
                 18.73 
                 18.38 
                 18.38 
                 18.41 
                 18.44 
                 17.37 
                 17.45 
                 17.39 
               
               
                 R 2 O + RO 
                 18.82 
                 18.44 
                 18.75 
                 18.40 
                 19.39 
                 19.36 
                 19.39 
                 19.37 
                 19.39 
                 19.32 
               
               
                 Li 2 O/Na 2 O 
                 0.89 
                 0.95 
                 0.97 
                 1.04 
                 0.84 
                 0.84 
                 0.83 
                 0.93 
                 0.93 
                 0.93 
               
               
                 SiO 2  + Al 2 O 3   
                 76.21 
                 76.57 
                 76.24 
                 76.55 
                 77.65 
                 77.67 
                 77.65 
                 77.66 
                 77.64 
                 77.74 
               
               
                 R 2 O/Al 2 O 3   
                 1.15 
                 1.12 
                 1.14 
                 1.12 
                 1.13 
                 1.13 
                 1.13 
                 1.07 
                 1.07 
                 1.07 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 81.13 
                 8151 
                 81.19 
                 81.55 
                 80.56 
                 80.59 
                 80.56 
                 80.58 
                 80.56 
                 80.63 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 9.18 
                 9.11 
                 8.79 
                 8.70 
                 9.61 
                 9.58 
                 9.63 
                 9.66 
                 8.60 
                 9.63 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.407 
                 2.403 
                 2.406 
                 2.401 
                 2.421 
                 2.435 
                 2.425 
                 2.422 
                 2.448 
                 2.436 
               
               
                 Strain Pt. (° C.) 
                 557 
                 558 
                 554 
                 560 
                 566 
                 562 
                 565 
                 573 
                 561 
                 565 
               
               
                 Anneal Pt. (° C.) 
                 606 
                 608 
                 604 
                 609 
                 615 
                 611 
                 614 
                 621 
                 611 
                 614 
               
               
                 Softening Pt. (° C.) 
                 843 
                 852 
                 843 
                 853 
                 856.4 
                 854 
                 854.8 
                 861.8 
                 853.9 
                 855.8 
               
               
                 10 11  Poise Temperature 
                 688 
                 692 
                 687 
                 692 
                 697 
                 693 
                 696 
                 702 
                 694 
                 696 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 82.9 
                 80.5 
                 81.9 
                 79.8 
                 81 
                 80.1 
                 80.6 
                 77.6 
                 76.3 
                 76.4 
               
               
                 Fulchers A 
                 −3.407 
                 −3.083 
                 −3.065 
                 −3.373 
                 −3.386 
                 −3.514 
                 −3.437 
                 −3.416 
                 −3.416 
                 −3.247 
               
               
                 Fulchers B 
                 8891.5 
                 8247.5 
                 8041.1 
                 8793.4 
                 8767.4 
                 9029.1 
                 8904.5 
                 8684 
                 8789 
                 8225.7 
               
               
                 Fulchers To 
                 25.7 
                 63.2 
                 83.9 
                 47.6 
                 46 
                 28.7 
                 34.7 
                 62.8 
                 42.7 
                 97.3 
               
               
                 200 P Temperature (° C.) 
                 1583 
                 1595 
                 1582 
                 1597 
                 1588 
                 1581 
                 1587 
                 1582 
                 1580 
                 1580 
               
               
                  35000 P Temperature  
                 1144 
                 1145 
                 1141 
                 1158 
                 1152 
                 1149 
                 1150 
                 1154 
                 1147 
                 1153 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1047 
                 1047 
                 1045 
                 1061 
                 1055 
                 1053 
                 1054 
                 1059 
                 1051 
                 1060 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 229 
                 229 
                 164 
                 116 
                 201 
                 212 
                 215 
                 132 
                 95 
                 82 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.949 
                 2.963 
                 2.932 
                 2.956 
                 2.924 
                 2.949 
                 2.956 
                 2.932 
                 2.99 
                 2.966 
               
               
                 Refractive Index 
                 1.5034 
                 1.5027 
                 1.5038 
                 1.5031 
                 1.507 
                 1.5084 
                 1.5074 
                 1.5081 
                 1.5103 
                 1.5091 
               
               
                 Young&#39;s Modulus (GPa) 
                 74.8 
                 74.7 
                 75.1 
                 75.2 
                 77.8 
                 77.4 
                 77.6 
                 78.5 
                 78.2 
                 78.5 
               
               
                   
               
               
                 Sample 
                 31 
                 32 
                 33 
                 34 
                 35 
                 36 
                 37 
                 38 
                 39 
                 40 
               
               
                   
               
               
                 SiO 2   
                 61.36 
                 61.41 
                 61.50 
                 61.36 
                 61.27 
                 61.51 
                 70.21 
                 68.19 
                 66.26 
                 72.19 
               
               
                 Al 2 O 3   
                 16.33 
                 16.23 
                 16.14 
                 16.29 
                 16.20 
                 16.27 
                 9.83 
                 11.85 
                 13.81 
                 9.94 
               
               
                 P 2 O 5   
                 2.97 
                 3.47 
                 2.99 
                 2.95 
                 2.97 
                 2.97 
                 0.00 
                 0.00 
                 0.05 
                 0.00 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.98 
                 1.91 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 8.35 
                 8.35 
                 8.37 
                 8.39 
                 8.37 
                 8.34 
                 6.01 
                 6.01 
                 6.01 
                 6.01 
               
               
                 Na 2 O 
                 10.45 
                 10.46 
                 10.42 
                 10.48 
                 9.90 
                 8.91 
                 13.89 
                 13.89 
                 13.86 
                 11.80 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 0.02 
                 0.02 
                 0.49 
                 0.24 
                 0.01 
                 0.01 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 ZnO 
                 0.46 
                 0.02 
                 0.02 
                 0.23 
                 0.23 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 SnO 2   
                 0.06 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.00 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 24.68 
                 24.57 
                 24.51 
                 24.67 
                 24.58 
                 24.62 
                 15.84 
                 17.86 
                 19.82 
                 15.95 
               
               
                 R 2 O 
                 18.81 
                 18.81 
                 18.80 
                 18.87 
                 18.28 
                 17.26 
                 19.91 
                 19.91 
                 19.88 
                 17.82 
               
               
                 R 2 O + RO 
                 19.28 
                 18.85 
                 19.31 
                 19.35 
                 18.53 
                 17.28 
                 19.91 
                 19.91 
                 19.88 
                 17.82 
               
               
                 Li 2 O/Na 2 O 
                 0.80 
                 0.80 
                 0.80 
                 0.80 
                 0.85 
                 0.94 
                 0.43 
                 0.43 
                 0.43 
                 0.51 
               
               
                 SiO 2  + Al 2 O 3   
                 77.69 
                 77.63 
                 77.64 
                 77.64 
                 77.47 
                 77.78 
                 80.04 
                 80.04 
                 80.07 
                 82.13 
               
               
                 R 2 O/Al 2 O 3   
                 1.15 
                 1.16 
                 1.16 
                 1.16 
                 1.13 
                 1.06 
                 2.02 
                 1.68 
                 1.44 
                 1.79 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 80.66 
                 81.10 
                 80.63 
                 80.60 
                 81.42 
                 82.67 
                 80.04 
                 80.04 
                 80.12 
                 82.13 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 9.66 
                 9.72 
                 9.63 
                 9.61 
                 9.72 
                 9.91 
                 13.32 
                 13.32 
                 13.33 
                 13.67 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.428 
                 2.414 
                 2.42 
                 2.424 
                 2.409 
                 2.396 
                 2.425 
                 2.433 
                 2.440 
                 2.408 
               
               
                 Strain Pt. (° C.) 
                 561 
                 568 
                 565 
                 562 
                 552 
                 546 
                 458 
                 475 
                 499 
                 470 
               
               
                 Anneal Pt. (° C.) 
                 611 
                 618 
                 614 
                 612 
                 604 
                 598 
                 499 
                 517 
                 542 
                 513 
               
               
                 Softening Pt. (° C.) 
                 850.4 
                 861.2 
                 854.4 
                 853.3 
                 847.5 
                 847.1 
                 705 
                 731 
                 769 
                 735 
               
               
                 10 11  Poise Temperature 
                 694 
                 701 
                 696 
                 695 
                 689 
                 684 
                 568 
                 589 
                 616 
                 587 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 82 
                 82.7 
                 82.7 
                 82.2 
                 81.1 
                 76.9 
                 87.1 
                 87.7 
                 88.2 
                 80.3 
               
               
                 Fulchers A 
                 −3.507 
                 −3.68 
                 −3.151 
                 −3.428 
                 −3.51 
                 −3.293 
                 −1.855 
                 −2.373 
                 −2.668 
                 −1.950 
               
               
                 Fulchers B 
                 9164.8 
                 9566 
                 8306 
                 8922.5 
                 9133.7 
                 8482.9 
                 6336.7 
                 7638.0 
                 8386.1 
                 6900.0 
               
               
                 Fulchers To 
                 13.3 
                 −0.4 
                 68.6 
                 30.2 
                 15.2 
                 59.6 
                 18.9 
                 −55.9 
                 −76.3 
                 −3.6 
               
               
                 200 P Temperature (° C.) 
                 1591 
                 1599 
                 1592 
                 1588 
                 1587 
                 1576 
                 1544 
                 1578 
                 1611 
                 1620 
               
               
                  35000 P Temperature  
                 1152 
                 1163 
                 1148 
                 1149 
                 1149 
                 1142 
                 1009 
                 1048 
                 1086 
                 1059 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1054 
                 1065 
                 1051 
                 1052 
                 1052 
                 1047 
                 904 
                 939 
                 976 
                 948 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 195 
                 296 
                 308 
                 314 
                 253 
                 127 
                   
                   
                   
                   
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.936 
                 2.939 
                 2.933 
                 2.925 
                 2.978 
                 3.047 
                 2.851 
                 2.848 
                 2.862 
                 2.925 
               
               
                 Refractive Index 
                 1.5074 
                 1.5052 
                 1.5064 
                 1.5071 
                 1.5055 
                 1.5046 
                 1.5054 
                 1.5073 
                 1.5089 
                 1.5028 
               
               
                 Young&#39;s Modulus (GPa) 
                 77.4 
                 76.1 
                 77.2 
                 76.7 
                 76.5 
                 75.3 
                 76.1 
                 77.2 
                 77.6 
                 76.3 
               
               
                   
               
               
                 Sample 
                 41 
                 42 
                 43 
                 44 
                 45 
                 46 
                 47 
                 48 
                 49 
                 50 
               
               
                   
               
               
                 SiO 2   
                 70.06 
                 68.13 
                 67.46 
                 66.33 
                 65.30 
                 64.26 
                 63.28 
                 61.85 
                 64.37 
                 63.47 
               
               
                 Al 2 O 3   
                 11.72 
                 13.77 
                 14.72 
                 15.76 
                 16.56 
                 16.85 
                 16.41 
                 16.67 
                 16.86 
                 16.75 
               
               
                 P 2 O 5   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 6.01 
                 6.01 
                 5.71 
                 5.67 
                 5.69 
                 5.83 
                 5.61 
                 5.76 
                 5.81 
                 5.70 
               
               
                 Na 2 O 
                 12.15 
                 12.03 
                 12.03 
                 12.16 
                 12.37 
                 11.94 
                 12.37 
                 12.38 
                 11.87 
                 11.96 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 0.00 
                 0.00 
                 0.02 
                 0.02 
                 0.02 
                 1.07 
                 2.28 
                 3.29 
                 1.03 
                 2.07 
               
               
                 ZnO 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 17.73 
                 19.78 
                 20.43 
                 21.43 
                 22.25 
                 22.68 
                 22.02 
                 22.43 
                 22.67 
                 22.44 
               
               
                 R 2 O 
                 18.17 
                 18.05 
                 17.75 
                 17.84 
                 18.07 
                 17.77 
                 17.98 
                 18.15 
                 17.69 
                 17.67 
               
               
                 R 2 O + RO 
                 18.17 
                 18.05 
                 17.77 
                 17.86 
                 18.09 
                 18.85 
                 20.26 
                 21.44 
                 18.72 
                 19.73 
               
               
                 Li 2 O/Na 2 O 
                 0.49 
                 0.50 
                 0.47 
                 0.47 
                 0.46 
                 0.49 
                 0.45 
                 0.47 
                 0.49 
                 0.48 
               
               
                 SiO 2  + Al 2 O 3   
                 81.78 
                 81.90 
                 82.19 
                 82.09 
                 81.86 
                 81.11 
                 79.69 
                 78.51 
                 81.23 
                 80.22 
               
               
                 R 2 O/Al 2 O 3   
                 1.55 
                 1.31 
                 1.20 
                 1.13 
                 1.09 
                 1.05 
                 1.10 
                 1.09 
                 1.05 
                 1.05 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 81.78 
                 81.90 
                 82.19 
                 82.09 
                 81.86 
                 81.11 
                 79.69 
                 78.51 
                 81.23 
                 80.22 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 13.61 
                 13.63 
                 14.41 
                 14.47 
                 14.39 
                 13.91 
                 14.21 
                 13.63 
                 13.98 
                 14.08 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.418 
                 2.424 
                 2.425 
                 2.429 
                 2.431 
                 2.438 
                 2.448 
                 2.456 
                 2.438 
                 2.448 
               
               
                 Strain Pt. (° C.) 
                 486 
                 517 
                 540 
                 565 
                 586 
                 593 
                 575 
                 573 
                 593 
                 575 
               
               
                 Anneal Pt. (° C.) 
                 530 
                 563 
                 590 
                 616 
                 638 
                 645 
                 625 
                 622 
                 645 
                 625 
               
               
                 Softening Pt. (° C.) 
                 758 
                 812 
                 843.8 
                 877.9 
                 906.7 
                 905 
                 875.3 
                 860.8 
                 905 
                 875 
               
               
                 10 11  Poise Temperature 
                 606 
                 643 
                 675 
                 703 
                 727 
                 733 
                 710 
                 704 
                 733 
                 710 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 81.7 
                 81.9 
                 81.9 
                 82.7 
                 83.7 
                 82.1 
                 82.2 
                 82.4 
                 82.10 
                 82.20 
               
               
                 Fulchers A 
                 −2.355 
                 −3.091 
                 −4.529 
                 −4.374 
                 −3.951 
                 −3.276 
                 −3.592 
                 −3.062 
                 −3.276 
                 −3.592 
               
               
                 Fulchers B 
                 7943.7 
                 9648.4 
                 13672.9 
                 12400.8 
                 10724.5 
                 8698.3 
                 9477.4 
                 8016.7 
                 8698.3 
                 9477.4 
               
               
                 Fulchers To 
                 −60 
                 −105.5 
                 −318.2 
                 −178.6 
                 −35.9 
                 93.6 
                 10.3 
                 98.2 
                 93.6 
                 10.3 
               
               
                 200 P Temperature (° C.) 
                 1646 
                 1684 
                 1684 
                 1679 
                 1679 
                 1653 
                 1619 
                 1593 
                 1653 
                 1619 
               
               
                  35000 P Temperature  
                 1091 
                 1158 
                 1189 
                 1212 
                 1227 
                 1206 
                 1175 
                 1152 
                 1206 
                 1175 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 978 
                 1044 
                 1073 
                 1103 
                 1123 
                 1108 
                 1076 
                 1057 
                 1108 
                 1076 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                   
                   
                 1472 
                   
                 3182 
                 1853 
                 1519 
                 387 
                 1853 
                 1519 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.909 
                 2.930 
                 2.944 
                 2.944 
                 2.938 
                 2.918 
                 2.873 
                 2.858 
                 2.918 
                 2.873 
               
               
                 Refractive Index 
                 1.5049 
                 1.5066 
                 1.5068 
                 1.5073 
                 1.5078 
                 1.5100 
                 1.5115 
                 1.5136 
                 1.5100 
                 1.5115 
               
               
                 Young&#39;s Modulus (GPa) 
                 76.9 
                 77.9 
                 78.2 
                 78.0 
                 78.3 
                 79.7 
                 79.9 
                 80.5 
                 79.7 
                 79.9 
               
               
                   
               
               
                 Sample 
                 51 
                 52 
                 53 
                 54 
                 55 
                 56 
                 57 
                 58 
                 59 
                 60 
               
               
                   
               
               
                 SiO 2   
                 63.29 
                 63.35 
                 63.24 
                 63.24 
                 63.40 
                 62.05 
                 62.24 
                 62.94 
                 61.72 
                 62.18 
               
               
                 Al 2 O 3   
                 17.46 
                 17.86 
                 17.09 
                 17.47 
                 16.16 
                 16.43 
                 16.30 
                 16.36 
                 16.52 
                 17.02 
               
               
                 P 2 O 5   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 1.10 
                 1.09 
                 0.00 
                 1.10 
                 1.10 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 5.72 
                 5.73 
                 6.00 
                 6.22 
                 6.73 
                 6.20 
                 7.03 
                 6.54 
                 6.92 
                 6.92 
               
               
                 Na 2 O 
                 11.93 
                 11.93 
                 12.00 
                 11.97 
                 13.64 
                 13.08 
                 13.27 
                 12.93 
                 12.60 
                 12.71 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 1.54 
                 1.07 
                 1.62 
                 1.05 
                 0.02 
                 1.08 
                 0.02 
                 1.18 
                 1.10 
                 0.02 
               
               
                 ZnO 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.04 
                 0.05 
                 0.04 
                 0.04 
               
               
                 Al 2 O 3  + Li 2 O 
                 23.18 
                 23.59 
                 23.09 
                 23.69 
                 22.89 
                 22.63 
                 23.33 
                 22.89 
                 23.44 
                 23.94 
               
               
                 R 2 O 
                 17.66 
                 17.67 
                 18.01 
                 18.19 
                 20.37 
                 19.29 
                 20.31 
                 19.48 
                 19.53 
                 19.63 
               
               
                 R 2 O + RO 
                 19.20 
                 18.74 
                 19.62 
                 19.24 
                 20.39 
                 20.38 
                 20.33 
                 20.65 
                 20.62 
                 19.66 
               
               
                 Li 2 O/Na 2 O 
                 0.48 
                 0.48 
                 0.50 
                 0.52 
                 0.49 
                 0.47 
                 0.53 
                 0.51 
                 0.55 
                 0.54 
               
               
                 SiO 2  + Al 2 O 3   
                 80.75 
                 81.21 
                 80.33 
                 80.71 
                 79.56 
                 78.48 
                 78.54 
                 79.30 
                 78.24 
                 79.20 
               
               
                 R 2 O/Al 2 O 3   
                 1.01 
                 0.99 
                 1.05 
                 1.04 
                 1.26 
                 1.17 
                 1.25 
                 1.19 
                 1.18 
                 1.15 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 80.75 
                 81.21 
                 80.33 
                 80.71 
                 79.56 
                 79.58 
                 79.63 
                 79.30 
                 79.33 
                 80.30 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 14.12 
                 14.17 
                 13.39 
                 12.98 
                 11.83 
                 12.83 
                 11.32 
                 12.13 
                 11.47 
                 11.61 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.443 
                 2.440 
                 2.444 
                 2.442 
                 2.400 
                 2.400 
                 2.400 
                 2.400 
                 2.400 
                 2.400 
               
               
                 Strain Pt. (° C.) 
                 601 
                 615 
                 584 
                 592 
                 524 
                 564 
                 545 
                 546 
                 559 
                 573 
               
               
                 Anneal Pt. (° C.) 
                 654 
                 670 
                 637 
                 644 
                 571 
                 614 
                 593 
                 594 
                 608 
                 624 
               
               
                 Softening Pt. (° C.) 
                 908 
                 926 
                 889 
                 898 
                 800 
                 857 
                 828 
                 834 
                 846 
                 869 
               
               
                 10 11  Poise Temperature 
                 742 
                 760 
                 724 
                 731 
                 649 
                 697 
                 673 
                 675 
                 690 
                 709 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 81.00 
                 80.90 
                 82.20 
                 82.30 
                 88.6 
                 86.6 
                 88.5 
                 87.2 
                 85.9 
                 87.2 
               
               
                 Fulchers A 
                 −3.607 
                 −3.554 
                 −3.468 
                 −3.723 
                 −3.311 
                 −2.657 
                 −3.409 
                 −3.487 
                 −3.067 
                 −3.525 
               
               
                 Fulchers B 
                 9163.8 
                 8892.3 
                 8990.5 
                 9397 
                 9487.1 
                 7241.1 
                 9457.1 
                 9503.6 
                 8245.3 
                 9417.5 
               
               
                 Fulchers To 
                 76.5 
                 118.3 
                 64.2 
                 59.4 
                 −89.7 
                 149.4 
                 −55.3 
                 −43.1 
                 61.3 
                 3.3 
               
               
                 200 P Temperature (° C.) 
                 1628 
                 1637 
                 1623 
                 1619 
                 1601 
                 1610 
                 1601 
                 1599 
                 1597 
                 1620 
               
               
                  35000 P Temperature  
                 1201 
                 1216 
                 1186 
                 1196 
                 1118 
                 1155 
                 1134 
                 1140 
                 1145 
                 1170 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1105 
                 1123 
                 1089 
                 1101 
                 1012 
                 1059 
                 1030 
                 1038 
                 1047 
                 1070 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 1275 
                 1401 
                 1378 
                 1147 
                 207 
                 1299 
                 805 
                 283 
                 906 
                 839 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.918 
                   
                 2.895 
                 2.908 
                 2.814 
                 2.888 
                 2.864 
                 2.852 
                 2.864 
                 2.888 
               
               
                 Refractive Index 
                 1.5111 
                   
                 1.5115 
                 1.5114 
                 1.5121 
                 1.5088 
                 1.5097 
                 1.5122 
                 1.5102 
                 1.5093 
               
               
                 Young&#39;s Modulus (GPa) 
                 80.0 
                   
                 80.0 
                 80.2 
                 79.4 
                 78.0 
                 77.9 
                 79.6 
                 78.8 
                 78.3 
               
               
                   
               
               
                 Sample 
                 61 
                 62 
                 63 
                 64 
                 65 
                 66 
                 67 
                 68 
                 69 
                 70 
               
               
                   
               
               
                 SiO 2   
                 62.34 
                 62.24 
                 62.32 
                 62.25 
                 62.24 
                 62.26 
                 61.38 
                 60.52 
                 59.63 
                 58.66 
               
               
                 Al 2 O 3   
                 17.25 
                 17.22 
                 17.22 
                 17.23 
                 17.24 
                 17.25 
                 16.32 
                 16.41 
                 16.48 
                 16.48 
               
               
                 P 2 O 5   
                 1.09 
                 1.06 
                 1.04 
                 1.05 
                 1.06 
                 1.05 
                 0.93 
                 1.93 
                 2.91 
                 3.93 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 7.14 
                 7.56 
                 7.70 
                 7.30 
                 7.57 
                 7.80 
                 7.00 
                 7.08 
                 7.17 
                 7.13 
               
               
                 Na 2 O 
                 12.11 
                 11.84 
                 11.64 
                 11.70 
                 11.42 
                 11.18 
                 12.71 
                 12.47 
                 12.27 
                 12.26 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.40 
                 0.40 
                 0.40 
                 0.52 
                 0.50 
                 0.49 
                 0.49 
               
               
                 MgO 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.03 
                 0.02 
                 1.09 
                 1.04 
                 1.01 
                 1.00 
               
               
                 ZnO 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.04 
                 0.04 
                 0.05 
                 0.04 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 24.39 
                 24.78 
                 24.93 
                 24.54 
                 24.82 
                 25.05 
                 23.32 
                 23.48 
                 23.65 
                 23.61 
               
               
                 R 2 O 
                 19.26 
                 19.41 
                 19.35 
                 19.40 
                 19.39 
                 19.38 
                 20.23 
                 20.05 
                 19.93 
                 19.88 
               
               
                 R 2 O + RO 
                 19.28 
                 19.44 
                 19.37 
                 19.42 
                 19.41 
                 19.40 
                 21.33 
                 21.09 
                 20.94 
                 20.89 
               
               
                 Li 2 O/Na 2 O 
                 0.59 
                 0.64 
                 0.66 
                 0.62 
                 0.66 
                 0.70 
                 0.55 
                 0.57 
                 0.58 
                 0.58 
               
               
                 SiO 2  + Al 2 O 3   
                 79.59 
                 79.46 
                 79.54 
                 79.48 
                 79.48 
                 79.51 
                 77.70 
                 76.93 
                 76.11 
                 75.14 
               
               
                 R 2 O/Al 2 O 3   
                 1.12 
                 1.13 
                 1.12 
                 1.10 
                 1.10 
                 1.10 
                 1.21 
                 1.19 
                 1.18 
                 1.18 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 80.68 
                 80.51 
                 80.59 
                 80.53 
                 80.54 
                 80.55 
                 78.63 
                 78.86 
                 79.02 
                 79.07 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 11.29 
                 10.65 
                 10.46 
                 11.03 
                 10.64 
                 10.33 
                 11.23 
                 11.15 
                 11.02 
                 11.09 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.434 
                 2.433 
                 2.432 
                 2.434 
                 2.433 
                 2.433 
                 2.449 
                 2.440 
                 2.436 
                 2.433 
               
               
                 Strain Pt. (° C.) 
                 585 
                 584 
                 590 
                 584 
                 584 
                 582 
                 538 
                 555 
                 566 
                 565 
               
               
                 Anneal Pt. (° C.) 
                 636 
                 636 
                 641 
                 635 
                 635 
                 634 
                 586 
                 601 
                 609 
                 607 
               
               
                 Softening Pt. (° C.) 
                 883.1 
                 878.9 
                 878.6 
                 879.5 
                 879.9 
                 879.3 
                 817.4 
                 836.8 
                 846.9 
                 844.2 
               
               
                 10 11  Poise Temperature 
                 721 
                 721 
                 724 
                 720 
                 720 
                 720 
                 666 
                 680 
                 685 
                 682 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 85.6 
                 85.9 
                 84.8 
                 86.6 
                 85.4 
                 86.1 
                 90.10 
                 90.10 
                 90.20 
                 90.60 
               
               
                 Fulchers A 
                 −3.325 
                 −3.869 
                 −3.268 
                 −3.432 
                 −3.955 
                 −3.373 
                   
                 −3.493 
                 −3.199 
                 −3.556 
               
               
                 Fulchers B 
                 8741 
                 10051.8 
                 8568.8 
                 9057.8 
                 10392.1 
                 8843.4 
                   
                 9216.9 
                 8403.2 
                 9085.3 
               
               
                 Fulchers To 
                 67.1 
                 −17.3 
                 75.5 
                 45.5 
                 −42.4 
                 57.3 
                   
                 −17.4 
                 49.2 
                 10.1 
               
               
                 200 P Temperature (° C.) 
                 1621 
                 1612 
                 1614 
                 1625 
                 1619 
                 1616 
                   
                 1573 
                 1577 
                 1561 
               
               
                  35000 P Temperature  
                 1178 
                 1177 
                 1172 
                 1181 
                 1180 
                 1174 
                   
                 1129 
                 1134 
                 1132 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1080 
                 1079 
                 1075 
                 1083 
                 1080 
                 1077 
                   
                 1031 
                 1038 
                 1036 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 788 
                 482 
                 512 
                 587 
                 604 
                 381 
                   
                 1530 
                 1519 
                 1638 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.930 
                 2.923 
                 2.922 
                 2.906 
                 2.903 
                 2.897 
                 2.823 
                 2.877 
                 2.880 
                 2.880 
               
               
                 Refractive Index 
                 1.5093 
                 1.5096 
                 1.5098 
                 1.5093 
                 1.5096 
                 1.5100 
                 1.5113 
                 1.5085 
                 1.5069 
                 1.5052 
               
               
                 Young&#39;s Modulus (GPa) 
                 78.5 
                 78.9 
                 78.7 
                 78.4 
                 78.9 
                 78.9 
                 79.4 
                 78.0 
                 77.0 
                 75.6 
               
               
                   
               
               
                 Sample 
                 71 
                 72 
                 73 
                 74 
                 75 
                 76 
                 77 
                 78 
                 79 
                 80 
               
               
                   
               
               
                 SiO 2   
                 57.73 
                 56.66 
                 64.38 
                 63.28 
                 62.39 
                 61.36 
                 60.45 
                 59.40 
                 64.30 
                 63.25 
               
               
                 Al 2 O 3   
                 16.49 
                 16.46 
                 16.17 
                 16.28 
                 16.25 
                 16.31 
                 16.30 
                 16.27 
                 16.15 
                 16.26 
               
               
                 P 2 O 5   
                 4.92 
                 5.91 
                 0.00 
                 0.94 
                 1.90 
                 2.94 
                 3.93 
                 5.02 
                 0.00 
                 0.97 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 7.11 
                 7.20 
                 8.65 
                 8.74 
                 8.77 
                 8.81 
                 8.83 
                 8.81 
                 9.25 
                 9.29 
               
               
                 Na 2 O 
                 12.21 
                 12.21 
                 10.72 
                 10.68 
                 10.61 
                 10.48 
                 10.45 
                 10.47 
                 10.22 
                 10.14 
               
               
                 K 2 O 
                 0.49 
                 0.49 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 1.00 
                 1.01 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
               
               
                 ZnO 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.00 
                 0.01 
                 0.05 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 23.60 
                 23.66 
                 24.82 
                 25.01 
                 25.02 
                 25.13 
                 25.13 
                 25.07 
                 25.40 
                 25.55 
               
               
                 R 2 O 
                 19.81 
                 19.91 
                 19.38 
                 19.43 
                 19.39 
                 19.31 
                 19.29 
                 19.29 
                 19.48 
                 19.44 
               
               
                 R 2 O + RO 
                 20.81 
                 20.92 
                 19.40 
                 19.45 
                 19.41 
                 19.33 
                 19.31 
                 19.31 
                 19.50 
                 19.46 
               
               
                 Li 2 O/Na 2 O 
                 0.58 
                 0.59 
                 0.81 
                 0.82 
                 0.83 
                 0.84 
                 0.85 
                 0.84 
                 0.90 
                 0.92 
               
               
                 SiO 2  + Al 2 O 3   
                 74.22 
                 73.12 
                 80.55 
                 79.56 
                 78.64 
                 77.68 
                 76.75 
                 75.67 
                 80.45 
                 79.52 
               
               
                 R 2 O/Al 2 O 3   
                 1.17 
                 1.18 
                 1.20 
                 1.19 
                 1.19 
                 1.18 
                 1.18 
                 1.19 
                 1.21 
                 1.19 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 79.14 
                 79.03 
                 80.55 
                 8050 
                 80.54 
                 80.62 
                 80.68 
                 80.69 
                 80.45 
                 80.49 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 11.13 
                 10.97 
                 9.31 
                 9.22 
                 9.18 
                 9.15 
                 9.13 
                 9.16 
                 8.70 
                 8.66 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.428 
                 2.425 
                 2.434 
                 2.429 
                 2.424 
                 2.419 
                 2.415 
                 2.411 
                 2.433 
                 2.426 
               
               
                 Strain Pt. (° C.) 
                 563 
                 545 
                 535 
                 553 
                 563 
                 562 
                 560 
                 551 
                 535 
                 552 
               
               
                 Anneal Pt. (° C.) 
                 608 
                 591 
                 582 
                 600 
                 612 
                 611 
                 609 
                 601 
                 581 
                 600 
               
               
                 Softening Pt. (° C.) 
                 837.6 
                 827.1 
                 818.1 
                 837.4 
                 849.8 
                 849.2 
                 849.8 
                 840.8 
                 810 
                   
               
               
                 10 11  Poise Temperature 
                 685 
                 670 
                 661 
                 679 
                 693 
                 692 
                 690 
                 683 
                 658 
                   
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 90.00 
                 90.30 
                 83.6 
                 83.8 
                 83.6 
                 84.6 
                 84.1 
                 84.2 
                 82.7 
                 82.5 
               
               
                 Fulchers A 
                 −3.161 
                 −3.588 
                 −3.826 
                 −3.63 
                 −2.79 
                 −3.512 
                 −3.12 
                 −3.28 
                 −2.877 
                 −3.537 
               
               
                 Fulchers B 
                 8180.3 
                 9097.4 
                 10478.8 
                 9677.6 
                 7575.6 
                 9191.9 
                 8193.7 
                 8569.4 
                 8126.3 
                 9491.6 
               
               
                 Fulchers To 
                 66.5 
                 3.9 
                 −115.5 
                 −39.6 
                 110.2 
                 5.7 
                 74.7 
                 43.8 
                 31 
                 −34.9 
               
               
                 200 P Temperature (° C.) 
                 1564 
                 1549 
                 1595 
                 1592 
                 1598 
                 1587 
                 1586 
                 1579 
                 1600 
                 1591 
               
               
                  35000 P Temperature  
                 1128 
                 1123 
                 1136 
                 1144 
                 1143 
                 1147 
                 1144 
                 1139 
                 1126 
                 1140 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1033 
                 1027 
                 1033 
                 1044 
                 1046 
                 1049 
                 1048 
                 1042 
                 1025 
                 1039 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 2331 
                 5458 
                 123 
                 148 
                 127 
                 215 
                 233 
                 388 
                 81 
                 124 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.889 
                 2.882 
                   
                 2.878 
                 2.900 
                 2.915 
                 2.914 
                 2.926 
                   
                 2.882 
               
               
                 Refractive Index 
                 1.5040 
                 1.5023 
                   
                 1.5111 
                 1.5089 
                 1.5070 
                 1.5055 
                 1.5036 
                   
                 1.5112 
               
               
                 Young&#39;s Modulus (GPa) 
                 74.7 
                 73.1 
                   
                 79.7 
                 78.5 
                 77.2 
                 75.8 
                 74.7 
                   
                 79.8 
               
               
                   
               
               
                 Sample 
                 81 
                 82 
                 83 
                 84 
                 85 
                 86 
                 87 
                 88 
                 89 
                 90 
               
               
                   
               
               
                 SiO 2   
                 62.53 
                 61.40 
                 60.37 
                 59.50 
                 64.10 
                 63.35 
                 62.25 
                 61.33 
                 60.37 
                 59.47 
               
               
                 Al 2 O 3   
                 16.28 
                 16.30 
                 16.27 
                 16.22 
                 16.31 
                 16.22 
                 16.33 
                 16.30 
                 16.28 
                 16.22 
               
               
                 P 2 O 5   
                 1.94 
                 2.91 
                 3.93 
                 4.87 
                 0.00 
                 0.94 
                 1.95 
                 2.88 
                 3.89 
                 4.85 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 9.11 
                 9.27 
                 9.31 
                 9.34 
                 9.83 
                 9.76 
                 9.86 
                 9.91 
                 9.86 
                 9.90 
               
               
                 Na 2 O 
                 10.06 
                 10.03 
                 10.03 
                 9.99 
                 9.68 
                 9.64 
                 9.55 
                 9.49 
                 9.52 
                 9.48 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
                 0.02 
               
               
                 ZnO 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 25.39 
                 25.57 
                 25.58 
                 25.56 
                 26.14 
                 25.99 
                 26.18 
                 26.21 
                 26.14 
                 26.11 
               
               
                 R 2 O 
                 19.17 
                 19.31 
                 19.34 
                 19.34 
                 19.52 
                 19.41 
                 19.41 
                 19.41 
                 19.39 
                 19.38 
               
               
                 R 2 O + RO 
                 19.20 
                 19.33 
                 19.37 
                 19.36 
                 19.54 
                 19.43 
                 19.44 
                 19.43 
                 19.41 
                 19.41 
               
               
                 Li 2 O/Na 2 O 
                 0.91 
                 0.92 
                 0.93 
                 0.94 
                 1.02 
                 1.01 
                 1.03 
                 1.04 
                 1.04 
                 1.04 
               
               
                 SiO 2  + Al 2 O 3   
                 78.81 
                 77.70 
                 76.65 
                 75.73 
                 80.41 
                 79.58 
                 78.57 
                 77.64 
                 76.65 
                 75.69 
               
               
                 R 2 O/Al 2 O 3   
                 1.18 
                 1.18 
                 1.19 
                 1.19 
                 1.20 
                 1.20 
                 1.19 
                 1.19 
                 1.19 
                 1.19 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 80.75 
                 80.62 
                 80.58 
                 80.59 
                 80.41 
                 80.52 
                 80.52 
                 80.52 
                 80.54 
                 80.54 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 8.87 
                 8.69 
                 8.66 
                 8.63 
                 8.18 
                 8.25 
                 8.17 
                 8.13 
                 8.17 
                 8.14 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.422 
                 2.418 
                 2.414 
                 2.410 
                 2.431 
                 2.425 
                 2.420 
                 2.416 
                 2.412 
                 2.408 
               
               
                 Strain Pt. (° C.) 
                 560 
                 563 
                 556 
                 547 
                 537 
                 550 
                 559 
                 561 
                 556 
                 547 
               
               
                 Anneal Pt. (° C.) 
                 609 
                 612 
                 606 
                 596 
                 584 
                 599 
                 608 
                 610 
                 605 
                 597 
               
               
                 Softening Pt. (° C.) 
                 844.9 
                 849.7 
                 845.3 
                 836.2 
                   
                   
                 841.4 
                 845 
                 841.7 
                 835.3 
               
               
                 10 11  Poise Temperature 
                 690 
                 693 
                 688 
                 677 
                   
                   
                 689 
                 691 
                 686 
                 679 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 82.8 
                 83.6 
                 83.5 
                 84 
                 81.7 
                 81.9 
                 82.6 
                 82.5 
                 83.3 
                 83.2 
               
               
                 Fulchers A 
                 −3.174 
                 −3.318 
                 −2.859 
                 −3.164 
                 −2.948 
                 −3.471 
                 −3.167 
                 −2.681 
                 −3.336 
                 −3.133 
               
               
                 Fulchers B 
                 8419.1 
                 8713 
                 7568.2 
                 8218.3 
                 8181 
                 9289.7 
                 8361.2 
                 7083.5 
                 8632.9 
                 8110.1 
               
               
                 Fulchers To 
                 56.7 
                 38.3 
                 114.3 
                 68.4 
                 32.2 
                 −23.8 
                 54.2 
                 163.2 
                 36.4 
                 71.8 
               
               
                 200 P Temperature (° C.) 
                 1594 
                 1589 
                 1581 
                 1572 
                 1591 
                 1586 
                 1583 
                 1585 
                 1568 
                 1564 
               
               
                  35000 P Temperature  
                 1148 
                 1147 
                 1137 
                 1135 
                 1124 
                 1135 
                 1139 
                 1144 
                 1132 
                 1128 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1050 
                 1049 
                 1042 
                 1039 
                 1024 
                 1035 
                 1042 
                 1051 
                 1036 
                 1033 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 113 
                 122 
                 170 
                 218 
                 48 
                 68 
                 62 
                 92 
                 86 
                 74 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.882 
                 2.907 
                 2.915 
                 2.917 
                   
                 2.879 
                 2.895 
                 2.899 
                 2.904 
                 2.924 
               
               
                 Refractive Index 
                 1.5090 
                 1.5072 
                 1.5057 
                 1.5042 
                   
                 1.5119 
                 1.5100 
                 1.5082 
                 1.5064 
                 1.5048 
               
               
                 Young&#39;s Modulus (GPa) 
                 78.3 
                 77.4 
                 76.2 
                 75.1 
                   
                 80.1 
                 78.8 
                 77.6 
                 76.5 
                 75.3 
               
               
                   
               
               
                 Sample 
                 91 
                 92 
                 93 
                 94 
                 95 
                 96 
                 97 
                 98 
                 99 
                 100 
               
               
                   
               
               
                 SiO 2   
                 60.33 
                 60.44 
                 60.38 
                 60.32 
                 60.45 
                 60.35 
                 61.46 
                 61.49 
                 61.41 
                 61.38 
               
               
                 Al 2 O 3   
                 16.31 
                 16.26 
                 16.28 
                 16.26 
                 16.27 
                 16.23 
                 16.26 
                 16.26 
                 16.23 
                 16.25 
               
               
                 P 2 O 5   
                 3.92 
                 3.88 
                 3.95 
                 4.00 
                 3.91 
                 4.02 
                 2.92 
                 2.90 
                 2.95 
                 2.97 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
               
               
                 Li 2 O 
                 8.38 
                 8.43 
                 8.37 
                 8.33 
                 8.45 
                 8.39 
                 7.80 
                 7.85 
                 7.87 
                 7.85 
               
               
                 Na 2 O 
                 10.00 
                 9.98 
                 9.97 
                 9.04 
                 8.97 
                 9.00 
                 10.49 
                 10.50 
                 10.51 
                 9.48 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 1.01 
                 0.02 
                 0.50 
                 1.99 
                 0.02 
                 1.01 
                 1.02 
                 0.02 
                 0.51 
                 2.01 
               
               
                 ZnO 
                 0.00 
                 0.94 
                 0.49 
                 0.00 
                 1.87 
                 0.95 
                 0.00 
                 0.93 
                 0.47 
                 0.00 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 24.69 
                 24.68 
                 24.65 
                 24.59 
                 24.72 
                 24.62 
                 24.06 
                 24.11 
                 24.10 
                 24.10 
               
               
                 R 2 O 
                 18.38 
                 18.42 
                 18.35 
                 17.38 
                 17.43 
                 17.40 
                 18.30 
                 18.35 
                 18.39 
                 17.34 
               
               
                 R 2 O + RO 
                 19.39 
                 19.37 
                 19.34 
                 19.37 
                 19.32 
                 19.36 
                 19.32 
                 19.31 
                 19.37 
                 19.36 
               
               
                 Li 2 O/Na 2 O 
                 0.84 
                 0.84 
                 0.84 
                 0.92 
                 0.94 
                 0.93 
                 0.74 
                 0.75 
                 0.75 
                 0.83 
               
               
                 SiO 2  + Al 2 O 3   
                 76.64 
                 76.70 
                 76.66 
                 76.58 
                 76.73 
                 76.57 
                 77.71 
                 77.74 
                 77.64 
                 77.62 
               
               
                 R 2 O/Al 2 O 3   
                 1.13 
                 1.13 
                 1.13 
                 1.07 
                 1.07 
                 1.07 
                 1.13 
                 1.13 
                 1.13 
                 1.07 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 80.56 
                 80.58 
                 80.61 
                 80.58 
                 80.63 
                 80.59 
                 80.63 
                 80.65 
                 80.59 
                 80.59 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 9.62 
                 9.56 
                 9.63 
                 9.67 
                 9.54 
                 9.60 
                 10.33 
                 10.28 
                 10.24 
                 10.26 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.418 
                 2.430 
                 2.423 
                 2.418 
                 2.444 
                 2.430 
                 2.422 
                 2.436 
                 2.428 
                 2.423 
               
               
                 Strain Pt. (° C.) 
                 563 
                 555 
                 558 
                 568 
                 555 
                 560 
                 570 
                 564 
                 566 
                 575 
               
               
                 Anneal Pt. (° C.) 
                 611 
                 606 
                 607.0 
                 616 
                 605 
                 610 
                 620 
                 615 
                 616 
                 624 
               
               
                 Softening Pt. (° C.) 
                 854.9 
                 850.1 
                 850.4 
                 857.2 
                 851.8 
                 852.1 
                 860.4 
                 858.1 
                 859.7 
                 865.6 
               
               
                 10 11  Poise Temperature 
                 695 
                 688 
                 689 
                 698 
                 688 
                 691 
                 701 
                 697 
                 699 
                 706 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 82.3 
                 80.6 
                 80.5 
                 77.3 
                 76.2 
                 76.4 
                 80.8 
                 81.2 
                 81 
                 78.1 
               
               
                 Fulchers A 
                 −3.335 
                 −3.361 
                 −3.421 
                 −3.467 
                 −3.405 
                 −3.44 
                 −3.108 
                 −3.484 
                 −3.386 
                 −2.992 
               
               
                 Fulchers B 
                 8633.5 
                 8739.7 
                 8866.5 
                 8755.7 
                 8753.7 
                 8798.6 
                 8110.4 
                 9086.5 
                 8788.5 
                 7780.3 
               
               
                 Fulchers To 
                 55 
                 39 
                 35.9 
                 54.3 
                 42.8 
                 42.9 
                 99.8 
                 27.8 
                 50.7 
                 115.7 
               
               
                 200 P Temperature (° C.) 
                 1587 
                 1583 
                 1585 
                 1572 
                 1577 
                 1575 
                 1599 
                 1598 
                 1596 
                 1586 
               
               
                  35000 P Temperature  
                 1151 
                 1145 
                 1149 
                 1147 
                 1144 
                 1145 
                 1160 
                 1160 
                 1159 
                 1148 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1055 
                 1048 
                 1052 
                 1053 
                 1048 
                 1049 
                 1064 
                 1062 
                 1062 
                 1054 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 243 
                 192 
                 257 
                 142 
                 108 
                 134 
                 367 
                 281 
                 314 
                 216 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.932 
                 2.966 
                 2.932 
                 2.934 
                 2.988 
                 2.961 
                 2.92 
                 2.962 
                 2.925 
                 2.929 
               
               
                 Refractive Index 
                 1.5055 
                 1.5067 
                 1.5059 
                 1.5060 
                 1.5086 
                 1.5069 
                 1.5062 
                 1.5075 
                 1.5070 
                 1.5074 
               
               
                 Young&#39;s Modulus (GPa) 
                 76.2 
                 76.1 
                 76.3 
                 77.2 
                 77.1 
                 77.2 
                 77.0 
                 77.3 
                 77.2 
                 78.2 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Sample 
                 101 
                 102 
                 103 
                 104 
                 105 
                 106 
                 107 
                 108 
               
               
                   
               
               
                 SiO 2   
                 61.27 
                 61.34 
                 61.36 
                 61.41 
                 61.50 
                 61.36 
                 61.27 
                 61.51 
               
               
                 Al 2 O 3   
                 16.24 
                 16.34 
                 16.33 
                 16.23 
                 16.14 
                 16.29 
                 16.20 
                 16.27 
               
               
                 P 2 O 5   
                 2.98 
                 2.96 
                 2.97 
                 3.47 
                 2.99 
                 2.95 
                 2.97 
                 2.97 
               
               
                 B 2 O 3   
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.98 
                 1.91 
               
               
                 Li 2 O 
                 7.98 
                 7.85 
                 8.35 
                 8.35 
                 8.37 
                 8.39 
                 8.37 
                 8.34 
               
               
                 Na 2 O 
                 9.50 
                 9.53 
                 10.45 
                 10.46 
                 10.42 
                 10.48 
                 9.90 
                 8.91 
               
               
                 K 2 O 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 MgO 
                 0.03 
                 1.00 
                 0.02 
                 0.02 
                 0.49 
                 0.24 
                 0.01 
                 0.01 
               
               
                 ZnO 
                 1.94 
                 0.93 
                 0.46 
                 0.02 
                 0.02 
                 0.23 
                 0.23 
                 0.00 
               
               
                 SnO 2   
                 0.05 
                 0.05 
                 0.06 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
                 0.05 
               
               
                 Al 2 O 3  + Li 2 O 
                 24.22 
                 24.19 
                 24.68 
                 24.57 
                 24.51 
                 24.67 
                 24.58 
                 24.62 
               
               
                 R 2 O 
                 17.49 
                 17.39 
                 18.81 
                 18.81 
                 18.80 
                 18.87 
                 18.28 
                 17.26 
               
               
                 R 2 O + RO 
                 19.45 
                 19.31 
                 19.28 
                 18.85 
                 19.31 
                 19.35 
                 18.53 
                 17.28 
               
               
                 Li 2 O/Na 2 O 
                 0.84 
                 0.82 
                 0.80 
                 0.80 
                 0.80 
                 0.80 
                 0.85 
                 0.94 
               
               
                 SiO 2  + Al 2 O 3   
                 77.51 
                 77.67 
                 77.69 
                 77.63 
                 77.64 
                 77.64 
                 77.47 
                 77.78 
               
               
                 R 2 O/Al 2 O 3   
                 1.08 
                 1.06 
                 1.15 
                 1.16 
                 1.16 
                 1.16 
                 1.13 
                 1.06 
               
               
                 SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 80.49 
                 80.64 
                 80.66 
                 81.10 
                 80.63 
                 80.60 
                 81.42 
                 82.67 
               
               
                 P 2 O 5   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (SiO 2  + Al 2 O 3  + B 2 O 3  +  
                 10.09 
                 10.27 
                 9.66 
                 9.72 
                 9.63 
                 9.61 
                 9.72 
                 9.91 
               
               
                 P 2 O 5 )/Li 2 O 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Density (g/cm 3 ) 
                 2.449 
                 2.437 
                 2.428 
                 2.414 
                 2.42 
                 2.424 
                 2.409 
                 2.396 
               
               
                 Strain Pt. (° C.) 
                 563 
                 565 
                 561 
                 568 
                 565 
                 562 
                 552 
                 546 
               
               
                 Anneal Pt. (° C.) 
                 614 
                 615 
                 611 
                 618 
                 614 
                 612 
                 604 
                 598 
               
               
                 Softening Pt. (° C.) 
                 859.2 
                 860.8 
                 850.4 
                 861.2 
                 854.4 
                 853.3 
                 847.5 
                 847.1 
               
               
                 10 11  Poise Temperature 
                 698 
                 699 
                 694 
                 701 
                 696 
                 695 
                 689 
                 684 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 CTE *10 −7  (1/° C.) 
                 77 
                 76.7 
                 82 
                 82.7 
                 82.7 
                 82.2 
                 81.1 
                 76.9 
               
               
                 Fulchers A 
                 −3.613 
                 −3.506 
                 −3.507 
                 −3.68 
                 −3.151 
                 −3.428 
                 −3.51 
                 −3.293 
               
               
                 Fulchers B 
                 9324.8 
                 8964.3 
                 9164.8 
                 9566 
                 8306 
                 8922.5 
                 9133.7 
                 8482.9 
               
               
                 Fulchers To 
                 1.6 
                 39.9 
                 13.3 
                 −0.4 
                 68.6 
                 30.2 
                 15.2 
                 59.6 
               
               
                 200 P Temperature (° C.) 
                 1578 
                 1584 
                 1591 
                 1599 
                 1592 
                 1588 
                 1587 
                 1576 
               
               
                  35000 P Temperature  
                 1145 
                 1153 
                 1152 
                 1163 
                 1148 
                 1149 
                 1149 
                 1142 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 200000 P Temperature  
                 1048 
                 1058 
                 1054 
                 1065 
                 1051 
                 1052 
                 1052 
                 1047 
               
               
                 (° C.) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Liquidus Viscosity  
                 143 
                 157 
                 195 
                 296 
                 308 
                 314 
                 253 
                 127 
               
               
                 (kiloPoise) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 SOC (nm/mm/MPa) 
                 2.987 
                 2.963 
                 2.936 
                 2.939 
                 2.933 
                 2.925 
                 2.978 
                 3.047 
               
               
                 Refractive Index 
                 1.5096 
                 1.5090 
                 1.5074 
                 1.5052 
                 1.5064 
                 1.5071 
                 1.5055 
                 1.5046 
               
               
                 Young&#39;s Modulus (GPa) 
                 77.9 
                 78.1 
                 77.4 
                 76.1 
                 77.2 
                 76.7 
                 76.5 
                 75.3 
               
               
                   
               
            
           
         
       
     
     All compositional components, relationships, and ratios described in this specification are provided in mol % unless otherwise stated. All ranges disclosed in this specification include any and all ranges and subranges encompassed by the broadly disclosed ranges whether or not explicitly stated before or after a range is disclosed. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents. 
     As used herein, a trailing 0 in a number is intended to represent a significant digit for that number. For example, the number “1.0” includes two significant digits, and the number “1.00” includes three significant digits.