# Patent

## Title
Glass composition having high thermal and chemical stability

## Abstract

Described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs) and active matrix organic light emitting diode displays (AMOLEDs). In accordance with certain of its aspects, the glasses possess good dimensional stability as a function of temperature.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation application and claims the benefit of priority to U.S. application Ser. No. 13/980,780 filed on Jul. 19, 2013, which claims the benefit of priority to PCT Application No. PCT/US12/22519 filed Jan. 25, 2012, which claims the benefit of priority to U.S. Provisional Application Ser. No. 61/435,987 filed on Jan. 25, 2011, the content of which is hereby incorporated by reference.


BACKGROUND
The production of liquid crystal displays such as, for example, active matrix liquid crystal display devices (AMLCDs) is very complex, and the properties of the substrate glass are extremely important. First and foremost, the glass substrates used in the production of AMLCD devices need to have their physical dimensions tightly controlled. The downdraw sheet drawing processes and, in particular, the fusion process described in U.S. Pat. Nos. 3,338,696 and 3,682,609, both to Dockerty, are capable of producing glass sheets that can be used as substrates without requiring costly post-forming finishing operations such as lapping and polishing. Unfortunately, the fusion process places rather severe restrictions on the glass properties, which require relatively high liquidus viscosities.
In the liquid crystal display field, thin film transistors (TFTs) based on poly-crystalline silicon are preferred because of their ability to transport electrons more effectively. Poly-crystalline based silicon transistors (p-Si) are characterized as having a higher mobility than those based on amorphous-silicon based transistors (a-Si). This allows the manufacture of smaller and faster transistors. P-Si displays are at the core of state-of-the-art handheld devices. The p-Si thin film transistor array consumes very low power, permits very fine features (critical for small displays), and provides high brightness.
The process used to make p-Si TFTs invariably includes a thermal excursion to quite high temperature to encourage the silicon to crystallize. In some processes, temperature alone is used to produce crystallization, and in such processes the peak temperatures are very high, very typically greater than 650° C. compared to the 350° C. peak temperatures employed in the manufacture of a-Si transistors. At these temperatures, most AMLCD glass substrates undergo a process known as compaction and will deform excessively unless supported from below. Compaction, also referred to as thermal stability or dimensional change, is an irreversible dimensional change (shrinkage or expansion) in the glass substrate due to changes in the glass' fictive temperature. The magnitude of compaction depends both on the process by which a glass is made and the viscoelastic properties of the glass. In the float process for producing sheet products from glass, the glass sheet is cooled relatively slowly from the melt and, thus, “freezes in” a comparatively low temperature structure into the glass. The fusion process, by contrast, results in very rapid quenching of the glass sheet from the melt, and freezes in a comparatively high temperature structure. As a result, a glass produced by the float process possesses less compaction when compared to glass produced by the fusion process. In the glass product itself, the compaction ultimately may produce poor registry with the color filter and, if large enough, adversely affect device performance. Thus, it would be desirable to minimize the level of compaction in a glass substrate that is produced by a downdraw process. A commercial glass product, Jade® (Corning Incorporated, Corning N.Y.), was developed expressly to address this problem. It has a very high annealing point compared to conventional amorphous silicon substrate glasses, and thus shows low compaction even when reheated above the strain point of conventional amorphous silicon substrates.
While the Jade® product has proven sufficient for many p-Si processes, there is still a demand for even lower levels of compaction and/or the capability of withstanding heat treatments at even higher temperatures, sometimes in excess of 700° C. Annealed low annealing point p-Si substrate glasses can be optimized to provide these lower levels of compaction but their deformation at elevated temperature is only marginally improved with this increased anneal. The Jade® product has better deformation at elevated temperatures than annealed low annealing point glasses but has too much compaction for some applications and may need even more resistance to deformation under the extreme conditions of some newly developed cycles. In order to provide the desired lower compaction in existing processes as well as enabling the development of new higher temperature processes, a glass with an annealing point in excess of 785° C. is desired.
SUMMARY
In accordance with the purposes of the disclosed materials, compounds, compositions, articles, devices, and methods, as embodied and broadly described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs) and active matrix organic light emitting diode displays (AMOLEDs). In accordance with certain of its aspects, the glasses possess good dimensional stability as a function of strain point. Specifically, the glasses described herein are fusion-compatible glasses with an anneal point in excess of 785° C., with a temperature at 200 poise of 1730° C. or less, with a density less than 2.65 g/cc, and with etch rates in fluoride-based mineral acids within 10% of the range exhibited by conventional a-Si substrate materials. Additional advantages will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the aspects described below. The advantages described below will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive.



BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects described below.
FIG. 1 is a comparison of the compaction of a glass typical of this invention with typical p-Si glasses.
FIG. 2 shows thermal sag (measured as “Deflection” in the y-axis) at 700° C. of commercially available p-Si glasses relative to glasses typical of this invention. It is clear the GBII glass has superior sag behavior at 700° C. than either other p-Si glass, thereby enabling higher temperature thermal cycles in customers' processes.
FIG. 3 illustrates the (SiO2+Al2O3)/(1−B2O3/100) vs. (RO—Al2O3)/(1−B2O3/100), in mole- % for glasses of the present disclosure.



DETAILED DESCRIPTION
The materials, compounds, compositions, articles, devices, and methods described herein may be understood more readily by reference to the following detailed description of specific aspects of the disclosed subject matter and the Examples included therein and to the Figures.
Before the present materials, compounds, compositions, articles, devices, and methods are disclosed and described, it is to be understood that the aspects described below are not limited to specific synthetic methods or specific reagents, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.
Also, throughout this specification, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which the disclosed matter pertains. The references disclosed are also individually and specifically incorporated by reference herein for the material contained in them that is discussed in the sentence in which the reference is relied upon.
Throughout the description and claims of this specification the word “comprise” and other forms of the word, such as “comprising” and “comprises,” means including but not limited to, and is not intended to exclude, for example, other additives, components, integers, or steps.
Certain materials, compounds, compositions, and components disclosed herein can be obtained commercially or readily synthesized using techniques generally known to those of skill in the art. For example, the starting materials and reagents used in preparing the disclosed compounds and compositions are either available from commercial suppliers or prepared by methods known to those skilled in the art.
Also, disclosed herein are materials, compounds, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are products of the disclosed methods and compositions. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds may not be explicitly disclosed, each is specifically contemplated and described herein.
Reference will now be made in detail to specific aspects of the disclosed materials, compounds, compositions, articles, and methods, examples of which are illustrated in the accompanying Examples and Figures.
Described herein are alkali-free glasses and methods for making the same that possess high strain points and, thus, good dimensional stability (i.e., low compaction). A high strain point glass can prevent panel distortion due to compaction/shrinkage during thermal processing subsequent to manufacturing of the glass.
The compositions represented by ranges of the present disclosure comprise SiO2, Al2O3, B2O3, MgO, CaO, SrO and BaO, and fining agents may include tin oxide (SnO2), iron oxide (Fe2O3), cerium oxide (CeO2) various halides (principally F, Cl and Br), As2O3 or Sb2O3. In one embodiment, the composition comprises an alkali-free glass comprising in mol percent on an oxide basis:

70≦SiO2≦74.5

10.5≦Al2O3≦13.5

0≦B2O3≦2.5

3≦MgO≦7

3≦CaO≦7

0≦SrO≦4

1.5≦BaO≦6

0≦SnO2≦0.3

0≦CeO2≦0.3

0≦As2O3≦0.5

0≦Sb2O3≦0.5

0.01≦Fe2O3≦0.08

F+Cl+Br≦0.4

wherein

    
    
        a) 1.05≦RO/Al2O3≦1.7
        b) 0.2≦MgO/RO≦0.45

where Al2O3, MgO, CaO, SrO and BaO represent the mol percents of the representative oxide components and RO=MgO+CaO+SrO+BaO. In another embodiment, the MgO/RO: is 0.29≦MgO/(MgO+CaO+SrO+BaO) ≦0.39.

    
    


In one embodiment, the compositions are further constrained as follows:

(SiO2+Al2O3)/(1−B2O3/100)=86.97−0.713*(MgO+CaO+SrO+BaO−Al2O3)/(1−B2O3/100)±0.8

In another embodiment, glasses within the disclosed ranges are substantially free of arsenic oxide (As2O3) or antimony oxide (Sb2O3) such that the concentration of either or both of these oxides is less than 0.05 wt %. When this is the case, it may be preferable to add other multivalent oxides such as SnO2, Fe2O3 and/or CeO2 to ensure a minimum number of gaseous inclusions in the final glass.
In one embodiment, the glasses of the present disclosure exhibit a density less than 2.65 g/cc. In another embodiment the glasses exhibit densities of less than 2.6 g/cc.
Compositions falling within the above defined ranges are shown in Table 1.
The temperature corresponding to 200 poise is often used as a rough guideline for the appropriate melting temperature of a glass. The 200 poise temperatures of the glasses in Table 1 are, for the most part, very high, generally greater than about 1670° C. A surprising result obtained for the inventive glasses is that at the low B2O3 contents of the inventive ranges, the melting rate of the most refractory batch materials, notably SiO2 (or sand), is accelerated relative to glasses with higher B2O3 contents. Because of this, and because of the comparatively low resistivity of these glasses compared to glasses with higher B2O3 contents, when the inventive glasses are melted in a joule-boosted CU melter with a platinum finer and optical stirrer, excellent glass quality is obtained for melter temperatures anywhere between about 200 and 450 poise.
The temperature corresponding to 35,000 poise viscosity is regarded as a metric for the temperature at which glass is delivered to the trough of the isopipe. It is generally desirable that this temperature be as low as possible to minimize creep of the isopipe refractory over time. The inventive glasses generally have 35,000 poise temperatures between about 1280° C. and 1345° C., but at the high end of this range, it might be necessary to use a special refractory for the isopipe to obtain acceptable isopipe lifetime. Therefore, in one embodiment, the inventive glasses have 35,000 poise temperatures less than 1320° C., and in another embodiment, less than 1310° C.
Fusion-drawn glass has a high fictive temperature, and this results in a substantial disequilibrium of the glass structure when reheated to temperatures close to the annealing point. If as-drawn glass is to be used in a p-Si process, the only means to minimize compaction are to anneal the glass at a temperature close to the annealing point, and thereby partially or entirely structurally relax the glass, or to increase the anneal point of the glass such that the rate of structural relaxation is reduced, and the magnitude of structural relaxation in the p-Si process is minimized. Unfortunately, the annealing point required to produce low levels of compaction in p-Si processes depends upon the details of the process, and is difficult to predict without running glasses with a variety of annealing points through the thermal cycle of interest. In general, to provide a consistent product to customers with different p-Si processes, the best means to minimize compaction is to make the annealing point as high as reasonably achieved consistent with manufacturability and other customer-related constraints. The inventive glasses have annealing temperatures greater than about 790° C., greater than any commercially-available substrate for AMLCD applications, and thus are great enough to produce minimal compaction in p-Si processes. In another embodiment, the annealing temperature exceeds 800° C. In yet another embodiment the annealing temperature exceeds 810° C. In another embodiment the annealing temperature exceeds 815° C.
Each oxide constituent in the inventive glasses serves an important purpose. Silica, or SiO2, is the primary glass forming oxide, and contributes viscosity to the molten glass. For a given liquidus temperature, increasing viscosity serves to increase liquidus viscosity, and thus to improve compatibility with the fusion process. However, if viscosity becomes too high, then melting-related defects such as fining bubbles may appear, and erosion of refractories and degradation of platinum may become too extreme to permit long-term manufacturing in a continuous process. Furthermore, as silica increases, the liquidus temperature may increase due to increasing stability of cristobalite, a crystalline polymorph of SiO2 that is an undesirable devitrification phase in a continuous process. Compared to every oxide except boron oxide (B2O3), SiO2 decreases density and coefficient of thermal expansion, and relative to B2O3 it improves durability. SiO2 ranges between 70 and 74.5 mol % in the inventive glasses.
Aluminum oxide, or Al2O3, also serves as a glass former in the inventive glasses. Like SiO2, it contributes viscosity, and when carefully balanced against SiO2 concentration and the relative and absolute concentrations of alkaline earths, can be used to reduce liquidus temperature, thus enhancing liquidus viscosity. An increase in Al2O3 relative to every oxide except SiO2 results in improved durability in the kinds of acid-based etchants commonly used to etch display glasses in amorphous-silicon-based etching processes. Like SiO2, an increase in Al2O3 relative to the alkaline earths generally results in decreased density, decreased coefficient of thermal expansion, and improved durability. Of particular importance, increasing Al2O3 at the expense of any component save SiO2 will generally increase the anneal point, and thus a minimum amount of Al2O3 is required to obtain the high anneal points required for the p-Si application. Because of the need to balance Al2O3 against other oxides, the full range of Al2O3 content of the inventive glasses is between 10.5 and 13.5 mol %.
Boron oxide, or B2O3, is also a glass-forming oxide, and is used to reduce viscosity and, more importantly, to reduce liquidus temperature. In general, an increase in B2O3 of 1 mol % decreases the temperature at equivalent viscosity by 10-14° C., depending on the details of the glass composition and the viscosity in question. However, B2O3 can lower liquidus temperature by 18-22° C. per mol %, and thus has the effect of decreasing liquidus temperature more rapidly than it decreases viscosity, thereby increasing liquidus viscosity. As one moves to extremely low B2O3 contents, keeping all other oxides within their respective ranges, it generally becomes increasingly difficult to obtain a liquidus viscosity as high as 130 kpoise, or more preferably greater than 170 kpoise, a prerequisite for compatibility with the fusion process as practiced today. If one were to increase boron oxide concentration at the expense of other glass components, CTE and density will generally decrease, but anneal point will decrease sharply, by as much as 14° C. per mol %, which is highly detrimental for p-Si substrate applications. On the other hand, relative to the other components that can reduce viscosity, principally the alkaline earth oxides, increasing boron oxide actually improves durability in fluoride-containing acids, making the glass more compatible with etching processes designed for amorphous silicon substrate glasses. For these reasons, B2O3 is preferably kept between 0 and 2.5 mol %. In one embodiment, the glass is essentially free of B2O3.
A surprising discovery is that glasses with comparatively low liquidus temperatures—and hence high liquidus viscosities—can be obtained in boron-free glasses. As noted above, boron oxide decreases liquidus temperature more rapidly than it decreases viscosity, so in general additions of B2O3 improve liquidus viscosity. Furthermore, boron tends to reduce the composition dependence of liquidus temperature, such that a change in the relative concentration of a particular oxide in a boron-free glass will tend to cause a larger change to liquidus temperature than a change in a boron-containing glass. The unexpected result described herein is that for a narrow range of oxides other than B2O3, low liquidus temperatures can be obtained, and as these glasses are very viscous for reasons stated above, the corresponding liquidus viscosities can be very high and appropriate for the fusion process. For example, the liquidus viscosities of the glasses in Table 1 are about 130,000 poise or more, thus making them compatible with the fusion process. In addition, the fusion process operates over a particular range of viscosity: glass is delivered to the trough of the isopipe at a viscosity corresponding to 20,000-35,000 poise, and glass leaves the root of the isopipe in the form of a viscous ribbon at a viscosity corresponding to 100,000 poise or more. At the very high delivery temperatures of the inventive glasses, the rate of radiative heat loss is greater per unit area than for less viscous glasses simply because a substantial fraction of the black body radiation of the glass is at visible and near-infrared wavelengths, at which wavelengths the glass is substantially transparent. Therefore, practical implementation of the inventive glasses in the fusion process may require high liquidus viscosities compared to those that might otherwise work for amorphous silicon substrate glasses. Thus, in one embodiment, the glass composition has a liquidus viscosity of at least 170,000 poise.
Alkaline earth oxides, MgO, CaO, SrO and BaO, are essential constituents for manufacturing. Like B2O3, increasing alkaline earths relative to SiO2 or Al2O3 always decreases the viscosity of a glass melt at fixed temperature. Since high temperature is the main factor limiting the lifetimes of glass tanks and forming equipment, it is always desirable to reduce melting and forming temperatures as much as possible consistent with delivering an appropriate suite of glass properties to a customer. Unlike SiO2, Al2O3 and B2O3, increases in alkaline earths relative to the glass forming components generally degrade properties that are important for p-Si applications: CTE and density generally increase as alkaline earth oxides increase relative to SiO2, Al2O3 and B2O3, anneal point generally decreases, and durability moves increasingly far from standard amorphous silicon substrate glasses. The only final glass properties that benefits from higher alkaline earth concentration is Young's modulus, and for some combinations of alkaline earth increases, specific modulus. Young's modulus determines the stiffness of a sheet of glass, and thus making it as high as possible is valuable for glass handling. At fixed temperature, the sag of a sheet of glass with widely spaced supports beneath it is dictated by the specific modulus, or the ratio of Young's modulus and density. High alkaline earth concentrations generally increase density, and so work against the expected increase in Young's modulus. However, MgO and CaO increase density much more slowly than the large alkaline earths, Sr and Ba, and thus the relative proportions of the alkaline earths can be manipulated to obtain an optimal combination of Young's modulus and density, consistent with fusion compatibility. In one embodiment, the specific modulus is greater than 30 GPa cm3/gm. In another emdodiment, the specific modulus is greater than 31 GPa cm3/gm. In yet another embodiment, the specific modulus is greater than 31.5 GPa cm3/gm.
Mixtures of alkaline earths are also required to obtain low liquidus temperatures. The reasons behind this are complex. Without wishing to be bound by theory, the inventive ranges for the various alkaline earths have the effect of putting two or more crystalline phases on the liquidus for most glasses within the inventive ranges, one of which is cristobalite (SiO2), and one of which is an alkaline earth aluminosilicate. In barium-rich glasses, the alkaline earth aluminosilicate is often hexacelsian and solid solutions therein, expressed approximately as Ba1-x-y,Srx,CayMgzAl2-zSi2+zO8, where x, y and z are generally less than 0.5. In glasses with low barium concentrations, and thus correspondingly high CaO+SrO concentrations, the alkaline earth aluminosilicate is often anorthite or solid solutions therein, expressed approximately as Ca1-x-y,SrxBayAl2Si2O8. For Mg-rich compositions, the liquidus phase is sometimes cordierite or solid solutions therein, approximately Mg2Al4Si5O18. The best liquidus temperatures are generally obtained when two or more different aluminosilicate phases and cristobalite are on or close to the liquidus temperature. The relative competition of each phase for glass constituents has the effect of destabilizing other phases, and thus reduces not only the liquidus temperature, but the tendency to devitrify when undercooled in a manufacturing process.
At a fixed level of alkaline earth oxides, melting and forming temperatures are generally reduced when Ba, Sr or Ca is replaced with Mg. This is particularly important when (MgO+CaO+SrO+BaO)/Al2O3 (also referred to as RO/Al2O3) is close to 1.0, as their high melt temperatures may make them almost impossible to melt. However, MgO is a participant in hexacelsian and cordierite, and at low (MgO+CaO+SrO+BaO)/Al2O3 may stabilize mullite. Therefore, MgO needs to be confined to a narrow range of the total alkaline earth oxide concentration to obtain the best balance of viscosity and liquidus temperature: the molar ratio MgO/(MgO+CaO+SrO+BaO) is preferably kept in the range 0.2 to 0.45. In another embodiment this molar ratio is kept in the range of 0.29 to 0.39. In yet another embodiment, this molar ratio is kept in the range of 0.31 to 0.35.
The alkaline earth oxide with the greatest beneficial impact on liquidus temperature is barium oxide, BaO. Unfortunately, it also has the effect of increasing melting and delivery temperatures when substituted for any other alkaline earth oxide, and compromises final glass properties such as density, CTE and anneal point more so than any other alkaline earth oxide. Strontium oxide, SrO, can be increased at the expense of barium to offset some of these deleterious effects, but with much diminished benefit to liquidus temperature. Because hexacelsian is substantially a barium-strontium aluminosilicate, with comparatively low CaO and BaO, it is generally desirable to have CaO concentrations comparable to the combined concentration of BaO+SrO. As a result of these considerations, the inventive glass will have BaO between 1.5 and 6 mol %, SrO between 0 and 4 mol %, and CaO between 3 and 7 mol %. Compositions within these limits have attractive physical properties and liquidus viscosities suitable for down draw processes such as the fusion process.
Even if the melting temperature is comparatively low, the details of the melting equipment may make it difficult to clear gaseous inclusions from a glass melt. Those that remain appear as defects in the final ware. P-Si TFT manufacturers are extremely sensitive to defects that distort the surface of a sheet of glass, and since one cannot predict where a gaseous inclusion will end up relative to the surface of a sheet, gaseous inclusions must be avoided at all cost. Furthermore, for processing simplicity, TFT manufacturers often seek to have color filter glass made from the same substrate material used in the TFT manufacturing process, in which case gaseous inclusions can block pixels, thereby compromising performance of the entire device. To clear gaseous defects from the glass melt before it is made into sheet, it is conventional to add fining agents Fining agents are multivalent cations or halides that release gas at high temperature. Exemplary multivalent fining agents include, but are not limited to, As2O3, Sb2O3, SnO2, and Fe2O3. Waste streams containing arsenic and antimony are considered hazardous materials in some countries, and for this reason is may be desirable to limit their concentrations in the inventive glass. In a preferred embodiment of the inventive glasses, As2O3, Sb2O3, or combinations thereof are kept at a level of 500 ppm (0.05 wt %) or less.
Halogens that find use as fining agents include F, Cl and Br. Waste streams that contain halogens may also be regarded as hazardous materials in some countries, and their release during melting processes can cause excessive corrosion of steel ductwork and supports. On the other hand, melt systems can be designed to safely handle off-gas of halogens, and various choices of raw materials can be used to influence their retention in the final glass. Halogens are typically added as stable salts, which may include, but are not limited to, simple salts and hydrated salts of the alkaline earths or aluminum, such as MgF2, CaF2, SrF2, BaF2, MgCl2, CaCl2, SrCl2, BaCl2, MgCl2.4H2O, CaCl2.4H2O, SrCl2.4H2O, BaCl2.4H2O, MgBr2, CaBr2, SrBr2, BaBr2, MgBr2.4H2O, CaBr2.4H2O, SrBr2.4H2O, BaBr2.4H2O, AlCl3, AlCl3.6H2O, and other forms familiar to those skilled in the art of raw material selection. Fining is generally optimized at a relatively low level of halogen addition, and thus the inventive glasses have F+Cl+Br concentrations between 0 and 0.4 mol %. In a preferred embodiment, F+Cl+Br is less than 200 ppm, or 0.02 wt %.
FIG. 1 demonstrates a comparison of a glass typical of this invention (X) with typical p-Si glasses. Compaction is measured relative to a base composition 1 in both an internal compaction measurement and in a display manufacturing cycle, where 50% of 1 is considered an acceptable level of compaction and less than 25% of 1 is preferable. Glasses 1, 2, and 3 have been put through the display manufacturing process as well as our the inventor's simulated internal tests and are included to demonstrate the transparency of the internal simulation with actual display maker's feedback. Glass 4 is Corning's Jade® composition and Glass 5 is a typical annealed p-Si composition, both showing acceptable levels of compaction. Glass 6 is a “more annealed” p-Si glass demonstrating lower compaction relative to the “typical” Glass 5. It is clear that the glasses in this invention (typified by glass X) have comparable, if not superior, compaction performance than either annealed p-Si glass and clearly superior compaction relative to Jade®.
FIG. 2 demonstrates thermal sag (measured as “Deflection” in the y-axis) at 700° C. of typical p-Si glasses (Glass 6 and Jade®) relative to glasses typical of this invention (“X”). It is clear the X glass has superior sag behavior at 700° C. than either other p-Si glass, thereby enabling higher temperature thermal cycles for use in a display manufacturer's process.
FIG. 3 demonstrates an interesting relationship that was observed with respect to the ratio of the SiO2+Al2O3 content to 1−B2O3 content and the RO— Al2O3 content. Many of the advantageous compositions of the present invention were located on the line y=0.7132×+86.965, as demonstrated graphically in FIG. 3. Put another way, in one embodiment, the glasses of the present invention fall within the following relationship: (SiO2+Al2O3)/(1−B2O3/100)=86.97−0.713*(MgO+CaO+SrO+BaO−Al2O3)/(1−B2O3/100)±0.8.
EXAMPLES
The following examples are set forth below to illustrate the methods and results according to the disclosed subject matter. These examples are not intended to be inclusive of all aspects of the subject matter disclosed herein, but rather to illustrate representative methods and results. These examples are not intended to exclude equivalents and variations of the present invention which are apparent to one skilled in the art.
Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in ° C. or is at ambient temperature, and pressure is at or near atmospheric. There are numerous variations and combinations of reaction conditions, e.g., component concentrations, temperatures, pressures and other reaction ranges and conditions that can be used to optimize the product purity and yield obtained from the described process. Only reasonable and routine experimentation will be required to optimize such process conditions.
Table 1 shows an example of an exemplary inventive glass composition based from to Example 16 in Table 2, and a particular selection of raw materials for making it. As is known to those skilled in the art of glass manufacture, the particular choice of raw materials does not impact the final glass composition as the original raw materials are transformed into a single, uniform glass by the melting process. However, the actual choice of raw materials may be different than indicated in light of the particular requirements imposed by the limitations of a particular melting system, or by the cost of the raw materials, or both.
The primary source of SiO2 is sand. The sand can be obtained from one or more of a variety of sources, including sand deposits (beaches or dunes), sandstone, quartzite, or other sources known to those skilled in the art of raw material selection. Sand is often the primary source of alkali contamination in what would otherwise be alkali-free glasses, and therefore a careful selection of source material may be important to minimize this important contaminant. The size of the sand particles may influence the rate of melting, and in particular large sand grains may fail to melt completely, appearing in the wear as a knot or stone. To avoid this, it is generally preferable for more than 90% of all sand grains to pass through a standard #80 U.S. standard mesh size. Alumina itself is generally the least expensive raw material to add Al2O3 to a glass, but other materials such as the aluminosilicate kaolin or hydrous forms of alumina or polymorphs of Al2O3 can be used instead when raw material costs are less important.
While Example 16 does not intentionally contain B2O3, other examples do. B2O3 can be batched as boric anhydride (approximately 94+% B2O3, the balance being mostly H2O) or boric acid, approximately B(OH)3.
MgO is generally added as its oxide, while the other alkaline earths are typically batched as carbonates. Suitable carbonate sources for CaO include limestone and precipitated calcium carbonate (a refined limestone product). MgO can be batched with CaO in the form of dolomite, though this may also increase the amount of iron in the glass, and so may be undesirable as compared to a more predictable pure iron source. Most of the strontium and barium will generally be added as carbonates obtained by industrial chemical processes. However, to keep the batch adequately oxidized, it is generally desirable to include a nitrate source as well. Strontium nitrate is indicated in the batch, but barium nitrate will work just as well. In both cases, it is generally desirable to batch no more than about 1 mol % of the alkaline earth oxide as nitrates to reduce NOx emissions, but in other ways nitrates may assist melting, so the exact amount that will work best is generally the subject of trial-and-error investigation.
SnO2 is included in its usual role as a fining agent. More SnO2 generally equates to improved fining capacity, but as it is a comparatively expensive raw material, it is desirable to add no more than is required to drive gaseous inclusions to an appropriately low level. The SnO2 level of the inventive glass is preferably between 0.02 and 0.3 mol %.
A low amount of ZrO2 (zirconia) is included in this example. It serves no practical role in the melting or fining behavior of the glass, and imparts no interesting properties at such a low level. It is useful to include it in a laboratory-scale batch, however, because it will be introduced by contact of hot glass with zirconia-based refractory materials in the melter, and thus monitoring its level in the glass may be important to judging the rate of tank wear over time. A typical amount of ZrO in the final glass of one embodiment is less than 0.05 mol %. In another embodiment, the amount of ZrO is less than 500 ppm.
The batch shows a low level of iron. Some iron is all but unavoidable due to contamination introduced by raw materials, especially sand and typical sources of MgO. Iron may also be added to benefit fining, hydrogen permeation, or both. If deliberately added, iron oxalate is a particularly useful raw material, but other compounds of iron can be employed as well. Iron can impart color to the glass if it becomes too oxidized, and so the level of iron is preferably between 0.01 and 0.08 mol % to obtain the best balance between gaseous inclusion management and excessive color.
A significant amount of water accompanies boric acid and sand, and a significant amount of carbon dioxide accompanies the carbonate raw materials. CO2 is sparingly soluble in glass, so most of it is lost in the earliest stages of melting, and that which is trapped in gaseous inclusions is generally moved by action of the fining agent, e.g., SnO2 in the present example. A significant level of water may be retained in the glass, however, in the form of dissolved OH− ions. This results in a measurable OH− vibrational band near 3600 cm−1 in the near infrared. The intensity of this band above background through a 1 mm thick path length is referred to as βOH. It generally ranges from as low as 0.2 to as high as 0.7 in conventional amorphous silicon substrate glasses. Dissolved OH− has a large impact on the annealing point for alkali-free glasses, and therefore it is desirable to keep OH− as low as reasonably achievable for any given glass. Conventional electric-boost melters generally employ burners above the glass surface that generate a high water partial pressure and result in higher levels of water incorporation into the glass. Halides can be used to reduce the retained water level, and boosting the power delivered via electrodes and reducing the power delivered via burners can also help. Likewise, selecting a comparatively dry sand can produce enough of a change in dissolved OH− to significantly impact annealing point. βOH for the inventive glass is less than 0.55, in one embodiment, less than 0.5 in another embodiment, and less than 0.45 in yet another embodiment to maximize the annealing point of the final glass.
While the actual composition and the choice of raw materials in this example is quite specific, it will be obvious to one skilled in the art that alternative raw materials can be used to obtain the same final glass composition, and thus a particular set of raw materials must be selected so as to be best suited for a given melting/fining/forming process. Any other set of raw materials that results in an equivalent composition will therefore produce a glass that satisfies the basic requirement of high annealing point, low density, low CTE, and high durability required for low-temperature polysilicon applications.
Further and although the intended use for the disclosed glasses is in p-Si applications, it should be noted that the glasses may also be considered for a-Si, color filter substrate or other applications where the disclosed properties may be deemed advantageous.












TABLE 1









mol %
batch weight (g)





















SiO2
sand
71.86
596.99



Al2O3
alumina
11.72
174.35



MgO
magnesia
5.17
30.36



CaO
limestone
5.59
84.65



SrO
strontium carbonate
1.42
28.45



BaO
barium carbonate
4.05
119.78



SnO2
tin (IV) oxide, 10% C.B.
0.15
33



Fe2O3
iron oxalate 10% C.B.
0.02
5.349



ZrO2
zirconium oxide 20% C.B.
0.02
2.02










Example
Preparation of a Test Sample
TABLE 2 sets forth exemplary glass compositions in mol percent, as calculated on an oxide basis from the glass batches. These example glasses were prepared by melting 1,000-25,000 gram batches of each glass composition at a temperature and time to result in a relatively homogeneous glass composition, e.g. at a temperature of about 1625° C. for a period of about 4-16 hours in platinum crucibles. Also set forth are relevant glass properties for each glass composition, determined on the glasses in accordance with techniques conventional in the glass art. Thus, the linear coefficient of thermal expansion (CTE) over the temperature range 0-300° C. is expressed in terms of ×10−7/° C., the softening point (Soft. Pt.), and the annealing point (Ann Pt.), and strain point (Str. Pt.) are expressed in terms of ° C. These were determined from fiber elongation techniques (ASTM references E228-85, C338, and C336, respectively). The density (Den.), in terms of g/cm3, was measured via the Archimedes method (ASTM C693).
The 200 poise temperature (Melt. Temp., ° C.) (defined as the temperature at which the glass melt demonstrates a viscosity of 200 poises [20 Pa.s]) was calculated employing the Fulcher equation fit to the high temperature viscosity data (measure via rotating cylinders viscometry, ASTM C965-81). The liquidus temperature (Liq. Temp.) of the glass was measured using the standard liquidus method. This involves placing crushed glass particles in a platinum boat, placing the boat in a furnace having a region of gradient temperatures, heating the boat in an appropriate temperature region for 24 hours, and determining by means of microscopic examination the highest temperature at which crystals appear in the interior of the glass. The liquidus viscosity (Liq. Visc., in poises) was determined from this temperature and the coefficients of the Fulcher equation.
The remainder of properties listed in Table 2 are achieved through standard tests that are well known to those of skill in the industry.















TABLE 2








Example
1
2
3
4
5
6
7






SiO2
70.75
72.33
72.19
71.68
73.11
71.75
71.99



Al2O3
11.96
11.85
11.36
11.46
11.6
12.17
11.59



B2O3
1.23
0
1.55
1.6
0
0
0



MgO
5.88
4.92
4.73
4.44
4.81
5.93
5.51



CaO
5.3
5.16
5.22
5.37
5.19
5.28
5.41



SrO
2.04
3.11
1.87
2.44
1.35
2.1
1.18



BaO
2.68
2.46
2.95
2.81
3.81
2.61
4.16



SnO2
0.11
0.12
0.12
0.15
0.12
0.11
0.11



Fe2O3
0.02
0.02
0.01
0.02
0.01
0.02
0.03



ZrO2
0.02
0.02
0
0.02
0
0.03
0.02



RO/Al2O3
1.33
1.32
1.3
1.31
1.31
1.31
1.4



(RO − Al2O3)/(1 − B2O3/100)
3.99
3.8
3.46
3.66
3.56
3.75
4.67



(SiO2 + Al2O3)/(1 − B2O3/100)
83.74
84.18
84.87
84.49
84.71
83.92
83.58



MgO/(MgO + CaO + SrO + BaO)
0.37
0.31
0.32
0.29
0.32
0.37
0.34


Properties

1
2
3
4
5
6
7



Strain
740
761
742
740
765
764
759



Anneal
793
818
797
794
820
817
813



Soft (ppv)
1030.1
1059.5
1043.6
1042.5

1052.8
1052.3



CTE (disk)
36.2
36.1
35.6
35.3
36.7
35.9
36.4



Density
2.595
2.604
2.575
2.586
2.611
2.601
2.629



Young's modulus
12.178
12.187
11.904
11.92
12.076
12.371
12.12



specific modulus
32.4
32.3
31.9
31.8
31.9
32.8
31.8


Viscosity

1
2
3
4
5
6
7



A
−3.039
−3.318
−3.089
−2.936
−3.179
−2.77
−3.281



B
6851.7
7509.3
7314.4
6813.9
7321.7
6440.1
7682.3



To
380.6
364.2
347
391.5
376.7
423.8
329.9



200 poise 
1664
1701
1704
1693
1713
1694
1706



400 poise 
1595
1633
1632
1622
1643
1623
1636



35000 poise
1284
1319
1305
1302
1325
1304
1312


Gradient boat

1
2
3
4
5
6
7



internal
1210
1240
1225
1210
1250
1220
1220



internal viscosity
166737
180392.2
174482.4
244828.8
160304.6
208231.1
223783.5 



T(35 kp) - T(liq)
74
79
80
92
75
84
92

















mol %
Example
8
9
10
11
12
13






SiO2
71.21
72.48
71.79
71.33
71.33
73.59



Al2O3
11.59
11.73
12.61
11.49
11.58
11.37



B2O3
1.19
0
1.72
1.29
1.53
0



MgO
5.32
4.95
3.94
5.21
4.65
4.73



CaO
5.36
5.53
5.03
5.33
5.79
5.11



SrO
1.4
1.82
1.21
1.28
1.69
1.32



BaO
3.78
3.31
3.54
3.91
3.24
3.74



SnO2
0.11
0.14
0.12
0.11
0.15
0.12



Fe2O3
0.02
0.02
0.01
0.02
0.02
0.01



ZrO2
0.02
0.02
0.02
0.02
0.02
0



RO/Al2O3
1.37
1.33
1.09
1.37
1.33
1.31



(RO − Al2O3)/(1 − B2O3/100)
4.32
3.88
1.13
4.3
3.85
3.53



(SiO2 + Al2O3)/(1 − B2O3/100)
83.8
84.21
85.88
83.9
84.2
84.96



MgO/(MgO + CaO + SrO + BaO)
0.34
0.32
0.29
0.33
0.3
0.32


Properties

8
9
10
11
12
13



Strain
744
764
752
745
738
765



Anneal
797
818
806
798
794
821



Soft (ppv)
1038.6
1058

1035.1
1037.3
1073.1



CTE (disk)
36.5

35.5
33.8
36.8
35.9



Density
2.612
2.611

2.612
2.594
2.592



Young's modulus
12.083
12.086

12.003
11.932
12.011



specific modulus
31.9
31.9

31.7
31.7
31.9


Viscosity

8
9
10
11
12
13



A
−3.058
−2.963
−2.9388
−3.267
−3.416
-3.229



B
7027.4
6997.2
6854.51
7471.1
7756.7
7499



To
369.3
384.4
397.06
338.2
326.9
368.2



200 poise 
1681
1714
1705
1680
1684
1724



400 poise 
1611
1642
1634
1611
1616
1654



35000 poise
1294
1316
1313
1295
1301
1333


Gradient boat

8
9
10
11
12
13



internal
1190
1205
1185
1185
1200
1250



internal viscosity
319661.5
366379.8
576075.1
359537.7
293826.6 
188449.9



T(35 kp) - T(liq)
104
111
128
110
101
83






Example
14
15
16
17
18
19






SiO2
72.27
73.26
71.86
72.08
72.09
72.78



Al2O3
11.9
11.09
11.72
11.76
12.05
11.39



B2O3
0
1
0
0
0
0



MgO
4.92
4.61
5.17
5.34
5.4
4.91



CaO
6.16
4.98
5.59
5.44
5.38
5.44



SrO
2.13
1.29
1.42
1.6
2.03
1.68



BaO
2.46
3.63
4.05
3.62
2.93
3.65



SnO2
0.12
0.12
0.15
0.11
0.1
0.11



Fe2O3
0.02
0.01
0.02
0.02
0.01
0.02



ZrO2
0.02
0
0.02
0.02
0.02
0.02



RO/Al2O3
1.32
1.31
1.38
1.36
1.31
1.38



(RO − Al2O3)/(1 − B2O3/100)
3.77
3.45
4.51
4.24
3.69
4.29



(SiO2 + Al2O3)/(1 − B2O3/100)
84.17
85.2
83.58
83.84
84.14
84.17



MgO/(MgO + CaO + SrO + BaO)
0.31
0.32
0.32
0.33
0.34
0.31


Properties

14
15
16
17
18
19



Strain
765
749
760
759
762
762



Anneal
818
806
814
813
816
815



Soft (ppv)
1055.3
1059.6
1052.2
1051.4
1050
1056.8



CTE (disk)
35.9
35.8
37.3
36.1
37.1
37.2



Density
2.591
2.572
2.632
2.619
2.603
2.616



Young's modulus
12.228
11.769

12.158





specific modulus
32.5
31.5
0
32

0


Viscosity

14
15
16
17
18
19



A
−3.143
−3.447
−3.156
−3.201
−3.227
−2.954



B
7180.4
8201
7237.7
7221.9 
7345.25
7021.4



To
381.1
290.5
370.5
379.5
368.95
385.6



200 poise 
1700
1717
1697
1692
1698
1722



400 poise 
1631
1646
1627
1624
1629
1649



35000 poise
1315
1317
1310
1312
1314
1322


Gradient boat

14
15
16
17
18
19



internal
1240
1245
1195
1200
1225
1230



internal viscosity
164814.5
139615.3
419073.2
398867
225630.8
229748.9



T(35 kp) - T(liq)
75
72
115
112
89
92






Example
20
21
22
23
24
25






SiO2
72.19
71.45
73.18
72.39
72.65
71.59



Al2O3
12.2
12.05
11.95
11.74
11.72
11.73



B2O3
1
1.25
0.5
0
0
1.65



MgO
4.61
4.9
4.56
5.14
4.86
4.75



CaO
4.9
5.5
4.88
5.34
5.59
5.5



SrO
1.3
1.55
1.24
1.22
2.58
2



BaO
3.6
3.15
3.54
4.02
2.43
2.65



SnO2
0.16
0.12
0.13
0.11
0.12
0.12



Fe2O3
0.02
0.03
0.02
0.01
0.02
0.01



ZrO2
0.02
0
0
0.02
0.03
0



RO/Al2O3
1.18
1.25
1.19
1.34
1.32
1.27



(RO − Al2O3)/(1 − B2O3/100)
2.23
3.09
2.28
3.98
3.74
3.22



(SiO2 + Al2O3)/(1 − B2O3/100)
85.24
84.56
85.56
84.13
84.37
84.72



MgO/(MgO + CaO + SrO + BaO)
0.32
0.32
0.32
0.33
0.31
0.32


Properties

20
21
22
23
24
25



Strain
752
738
767
761
765
743



Anneal
807
793
821
817
819
797



Soft (ppv)
1050.2
1034.2
1069.5
1060.2
1058.6
1039.8



CTE (disk)
35.4
36.2
34.4
34
36.4
35.9



Density
2.603
2.603
2.577
2.62
2.594
2.574



Young's modulus

12.112
11.951
12.115
12.163
11.929



specific modulus
0
32.1
32
31.9
32.3
32


Viscosity

20
21
22
23
24
25



A
−3.232
−2.868
−3.354
−3.061
−2.77
−3.044



B
7311.1
6597.4
7841.5
7095.3
6633.3
7080.4



To
370.6
398
326.5
388.7
408.9
365.7



200 poise 
1692
1674
1713
1712
1717
1690



400 poise 
1624
1604
1643
1642
1644
1620



35000 poise
1311
1288
1319
1322
1316
1299


Gradient boat

20
21
22
23
24
25



internal
1220
1205
1230
1225
1240
1220



internal viscosity
237339.4
202869.5
211361.6
264945.4
162685.9
175369.9



T(35 kp) - T(liq)
91
83
89
97
76
79






Example
26
27
28
29
30
31






SiO2
71.71
72.7
72.21
71.14
72.85
71.97



Al2O3
11.24
11.38
11.62
11.27
11.37
12.02



B2O3
0
0
0
0.91
0
0



MgO
5.95
3.88
5.24
5.68
4.85
4.98



CaO
5.5
5.74
5.47
5.46
5.73
6.23



SrO
1.03
2.83
1.2
1.1
0.92
2.15



BaO
4.38
3.31
4.09
4.27
4.13
2.49



SnO2
0.11
0.11
0.11
0.11
0.11
0.12



Fe2O3
0.05
0.02
0.02
0.04
0.02
0.02



ZrO2
0.03
0.02
0.02
0.02
0.02
0.03



RO/Al2O3
1.5
1.38
1.38
1.46
1.37
1.32



(RO − Al2O3)/(1 − B2O3/100)
5.62
4.38
4.38
5.29
4.26
3.83



(SiO2 + Al2O3)/(1 − B2O3/100)
82.95
84.08
83.83
83.17
84.22
83.99



MgO/(MgO + CaO + SrO + BaO)
0.35
0.25
0.33
0.34
0.31
0.31


Properties

26
27
28
29
30
31



Strain
755
761
764
740
760
766



Anneal
807
816
816
793
814
819



Soft (ppv)
1043
1056.7
1047.7
1033.1
1058.9
1056



CTE (disk)

38.2

37
36.2




Density
2.637
2.627
2.625
2.629
2.618
2.593



Young's modulus
12.099
12.052
12.062
11.947
12.006
12.299



specific modulus
31.6
31.6
31.7
31.3
31.6
32.7


Viscosity

26
27
28
29
30
31



A
−2.927
−3.158
−3.245
−3
−2.577
−3.031



B
6767.8
7404.8
7464.1
6922.1
6367.7
7014.5



To
400.7
361.3
354.3
371.5
425.3
383.8



200 poise 
1695
1718
1700
1677
1731
1699



400 poise 
1625
1647
1631
1607
1655
1629



35000 poise
1307
1323
1313
1289
1320
1310


Gradient boat

26
27
28
29
30
31



internal
1200
1230
1200
1190
1210
1235



internal viscosity
346863.6 
232274.4
381015.8
286454.5
345001.5
162076.1



T(35 kp) - T(liq)
107
93
113
99
110
75






Example
32
33
34
35
36
37






SiO2
71.66
70.82
72
74.05
72.8
72.83



Al2O3
12.19
12.07
11.65
12.03
11.37
11.38



B2O3
0
1
1.65
0
0
0



MgO
6.22
6.01
4.75
4.34
4.29
5.38



CaO
5.33
5.27
5.3
4.73
5.72
5.19



SrO
2.25
2.16
1.5
1.18
2.08
0.88



BaO
2.18
2.5
3
3.53
3.57
4.19



SnO2
0.12
0.12
0.12
0.11
0.11
0.11



Fe2O3
0.02
0.02
0.03
0.01
0.02
0.02



ZrO2
0.02
0.03
0
0.02
0.02
0.02



RO/Al2O3
1.31
1.32
1.25
1.15
1.38
1.37



(RO − Al2O3)/(1 − B2O3/100)
3.79
3.91
2.95
1.75
4.29
4.26



(SiO2 + Al2O3)/(1 − B2O3/100)
83.85
83.73
85.05
86.08
84.17
84.21



MgO/(MgO + CaO + SrO + BaO)
0.39
0.38
0.33
0.31
0.27
0.34


Properties

32
33
34
35
36
37



Strain
764
745
740
774
760
761



Anneal
816
799
794
830
814
815



Soft (ppv)
1049.4
1034
1034.9
1079
1057.4
1056.4



CTE (disk)
35.9
37
34.8
34.3
36.8
36.9



Density
2.591
2.59
2.582
2.58
2.622
2.621



Young's modulus
12.402

11.99
11.981

12.113



specific modulus
33

32
32
0
31.9


Viscosity

32
33
34
35
36
37



A
−3.426 
−3.2055
−2.778
−2.998
−3.145
−2.35



B
7613.4 
7086.72
6477.2
7183
7387
5942.8



To
344.8
377.78
407.6
390.8
360.1
455.9



200 poise 
1674
1665
1683
1746
1717
1734



400 poise 
1608
1598
1612
1673
1645
1656



35000 poise
1300
1292
1292
1343
1321
1318


Gradient boat

32
33
34
35
36
37



internal
1230
1215
1200
1245
1210
1215



internal viscosity
149543.7
181587.2
248974.3
257654.5
352055.2
301123.4



T(35 kp) - T(liq)
70
77
92
98
111
103






Example
38
39
40
41
42
43






SiO2
71.6
72.61
72.31
71.69
72.31
71.27



Al2O3
11.81
11.81
11.59
11.88
12.04
12.27



B2O3
0
0
0
0
0
1.72



MgO
5.54
4.91
4.82
5.97
4.88
4.2



CaO
5.49
5.3
5.95
5.39
5.38
5.34



SrO
1.23
1.37
0.99
1.93
1.39
1.29



BaO
4.19
3.88
4.18
2.99
3.87
3.76



SnO2
0.11
0.12
0.11
0.11
0.11
0.12



Fe2O3
0.02
0.01
0.02
0.02
0.01
0.01



ZrO2
0.02
0
0.02
0.02
0
0.02



RO/Al2O3
1.39
1.31
1.38
1.37
1.29
1.19



(RO − Al2O3)/(1 − B2O3/100)
4.64
3.65
4.35
4.4
3.48
2.36



(SiO2 + Al2O3)/(1 − B2O3/100)
83.41
84.42
83.9
83.57
84.35
85



MgO/(MgO + CaO + SrO + BaO)
0.34
0.32
0.3
0.37
0.31
0.29


Properties

38
39
40
41
42
43



Strain
759
765
759
762
764
741



Anneal
811
819
813
814
818
794



Soft (ppv)
1049.2
1059.3
1055.6
1050.6





CTE (disk)
37.9
36.7
36.7
36.5

36.7



Density
2.632
2.624
2.627
2.612
2.617




Young's modulus
12.231
12.096
12.124
12.343
12.049




specific modulus
32
31.8
31.8
32.6
31.7



Viscosity

38
39
40
41
42
43



A
−3.603
−3.326
−3.147
−3.062
−2.976
−2.8813



B
8091.9
7540.6
7223.2
6951.8
7088.4
6732.21



To
319.2
361.5
376.4
388.2
371.8
389.92



200 poise 
1690
1702
1702
1684
1715
1689



400 poise 
1623
1634
1633
1616
1643
1618



35000 poise
1312
1320
1316
1302
1314
1297


Gradient boat

38
39
40
41
42
43



internal
1220
1250
1200
1220
1200
1185



internal viscosity
239891.6
144839.8
420026.6
197486.7
382650.4
385510.9



T(35 kp) - T(liq)
92
70
116
82
114
112






Example
44
45
46
47
48
49






SiO2
72.03
72.3
71.58
72.23
72.47
72.09



Al2O3
12.77
11.58
11.7
11.62
11.54
12.05



B2O3
1.72
0
1.25
0
0
0



MgO
3.82
4.97
4.86
5.56
5.24
5.47



CaO
4.89
5.68
5.26
5.27
5.35
4.66



SrO
1.18
1.28
1.4
0.96
0.72
1.84



BaO
3.44
4.04
3.8
4.2
4.53
3.75



SnO2
0.12
0.11
0.13
0.11
0.11
0.1



Fe2O3
0.01
0.02
0.02
0.02
0.02
0.01



ZrO2
0.02
0.02
0
0.02
0.02
0.02



RO/Al2O3
1.04
1.38
1.31
1.38
1.37
1.3



(RO − Al2O3)/(1 − B2O3/100)
0.57
4.39
3.67
4.37
4.3
3.67



(SiO2 + Al2O3)/(1 − B2O3/100)
86.28
83.88
84.33
83.85
84.01
84.14



MgO/(MgO + CaO + SrO + BaO)
0.29
0.31
0.32
0.35
0.33
0.35


Properties

44
45
46
47
48
49



Strain
750
762
739
757
761
764



Anneal
803
816
794
810
814
818



Soft (ppv)

1055.1
1035.4
1050.4
1057.2
1047



CTE (disk)
35.1
37.2
37.2
36.6
36.6
37.2



Density

2.625
2.614
2.623
2.625
2.63



Young's modulus

12.086
11.984
12.124
12.194




specific modulus

31.7
31.6
31.9
32



Viscosity

44
45
46
47
48
49



A
−3.2039 
−3.224
−2.978
−3.099
−3.327
−3.085



B
7359.53
7477.8
6940.6
7233.1
7780
7131.02



To
369.45
353.2
371.6
364.2
323.7
379.69



200 poise 
1706
1707
1686
1704
1706
1704



400 poise 
1637
1637
1615
1633
1636
1634



35000 poise
1319
1316
1294
1311
1312
1314


Gradient boat

44
45
46
47
48
49



internal
1210
1200
1190
1210
1200
1235



internal viscosity
356215.2
404256.1
318195.5
283651.6 
355826.3
178793.4



T(35 kp) - T(liq)
109
116
104
101
112
79






Example
50
51
52
53
54
55






SiO2
71.99
72.8
72.66
73.6
71.99
71.7



Al2O3
12.5
11.38
11.43
11.38
11.55
12.49



B2O3
0.5
0
0
0
1.64
1.25



MgO
4.75
5.12
5.15
4.73
4.68
4.75



CaO
5.1
5.33
4.8
5.1
5.42
5



SrO
1.3
1.14
2.22
1.32
1.97
2.35



BaO
3.7
4.08
3.58
3.74
2.61
2.25



SnO2
0.13
0.11
0.11
0.12
0.12
0.16



Fe2O3
0.02
0.02
0.02
0.01
0.01
0.02



ZrO2
0
0.02
0.02
0
0
0.03



RO/Al2O3
1.19
1.38
1.38
1.31
1.27
1.15



(RO − Al2O3)/(1 − B2O3/100)
2.36
4.29
4.32
3.51
3.18
1.88



(SiO2 + Al2O3)/(1 − B2O3/100)
84.91
84.18
84.09
84.98
84.93
85.26



MgO/(MgO + CaO + SrO + BaO)
0.32
0.33
0.33
0.32
0.32
0.33


Properties

50
51
52
53
54
55



Strain
762
761
762
765
742
749



Anneal
817
815
816
819
798
804



Soft (ppv)
1057.8
1058.3
1058.2
1060.3
1042.4
1043.7



CTE (disk)
34.9
35.5
36.9
35.8
35.1
34.2



Density
2.604
2.618
2.622
2.608
2.567
2.581



Young's modulus
12.12
12.03
12.099
12.025
11.921




specific modulus
32.1
31.7
31.8
31.8
32
0


Viscosity

50
51
52
53
54
55



A
−3.098
−3.374
−3.181
−3.449
−2.907
−3.169



B
7091.4
7781.6
7401.1
7934.3
6863.9
7018.1



To
391.2
338.5
363.3
337.7
380.6
391



200 poise 
1705
1710
1713
1718
1699
1674



400 poise 
1635
1641
1643
1649
1627
1607



35000 poise
1319
1321
1321
1330
1302
1301


Gradient boat

50
51
52
53
54
55



internal
1210
1215
1210
1240
1230
1225



internal viscosity
365361.7
319181.5
363172.2
221012.5
149238.4
176192.7



T(35 kp) - T(liq)
109
106
111
90
72
76






Example
56
57
58
59
60
61






SiO2
72.47
72.75
72.71
71.85
70.99
72.83



Al2O3
11.42
11.68
11.41
11.57
11.79
11.37



B2O3
1
0
0
0
1.2
0



MgO
4.76
4.84
4.95
5.56
5.57
4.87



CaO
5.13
5.08
5.45
5.49
5.36
5.53



SrO
1.33
3.06
1.5
1.22
1.84
0.93



BaO
3.76
2.42
3.82
4.15
3.08
4.31



SnO2
0.12
0.12
0.11
0.11
0.11
0.11



Fe2O3
0.01
0.02
0.02
0.02
0.02
0.02



ZrO2
0
0.02
0.02
0.02
0.03
0.02



RO/Al2O3
1.31
1.32
1.38
1.42
1.34
1.38



(RO − Al2O3)/(1 − B2O3/100)
3.6
3.72
4.31
4.85
4.11
4.27



(SiO2 + Al2O3)/(1 − B2O3/100)
84.74
84.43
84.12
83.42
83.79
84.2



MgO/(MgO + CaO + SrO + BaO)
0.32
0.31
0.31
0.34
0.35
0.31


Properties

56
57
58
59
60
61



Strain
752
764
759
760
744
760



Anneal
809
818
814
813
796
814



Soft (ppv)
1058.2
1056.5
1055.8
1052.3
1034.1
1059.6



CTE (disk)
34.8
36.1
37.2
38.3
36.1
36.6



Density
2.595
2.598
2.62
2.628
2.6
2.621



Young's modulus
11.92
11.927
12.288
12.14
12.051
12.01



specific modulus
31.7
31.7
32.3
31.9
32
31.6


Viscosity

56
57
58
59
60
61



A
−3.053
−3.214
−3.04
−3.017
−3.07
−3.315



B
7293.1
7452.5
7104.2
6965.6
7012.4
7912.6



To
358.8
357.5
382.9
390.6
370.9
314.4



200 poise 
1721
1709
1713
1700
1676
1723



400 poise 
1648
1639
1642
1630
1607
1652



35000 poise
1319
1318
1320
1312
1292
1321


Gradient boat

56
57
58
59
60
61



internal
1240
1235
1210
1210
1195
1210



internal viscosity
167235.2
190054.2
354232.1
304687.3
274891.6 
331109



T(35 kp) - T(liq)
79
83
110
102
97
111






Example
62
63
64
65
66
67






SiO2
70.77
72.3
71.68
72.37
73.61
71.53



Al2O3
11.9
11.84
12.13
12.12
12.08
11.9



B2O3
1.06
0
0
0
0
1.35



MgO
6
5.01
5.71
4.92
4.51
4.37



CaO
5.34
5.58
5.63
5.66
4.85
5.36



SrO
1.89
2.1
2.17
2.75
1.26
1.38



BaO
2.87
3.01
2.52
2.02
3.56
3.97



SnO2
0.11
0.12
0.12
0.12
0.12
0.12



Fe2O3
0.03
0.02
0.02
0.02
0.01
0.01



ZrO2
0.03
0.02
0.03
0.02
0
0.01



RO/Al2O3
1.35
1.33
1.32
1.27
1.17
1.27



(RO − Al2O3)/(1 − B2O3/100)
4.24
3.86
3.9
3.23
2.1
3.22



(SiO2 + Al2O3)/(1 − B2O3/100)
83.56
84.14
83.81
84.49
85.69
84.57



MgO/(MgO + CaO + SrO + BaO)
0.37
0.32
0.36
0.32
0.32
0.29


Properties

62
63
64
65
66
67



Strain
742
766
758
767
776
745



Anneal
795
820
815
820
830
800



Soft (ppv)
1029.6
1057.6
1052.7
1059.5
1077.1
1043.5



CTE (disk)
36.3
35.9
36.1
36
35.8
37



Density
2.603
2.604
2.597
2.586
2.591
2.603



Young's modulus
12.136
12.137
12.308
12.258
12.165
11.92



specific modulus
32.1
32.1
32.7
32.7
32.4
31.6


Viscosity

62
63
64
65
66
67



A
−3.035
−2.991
−3.143
−3.049
−3.566
−2.943



B
6870.8
7115.9
6986.1
7170.6
8149.3
6909.4



To
379.2
368.7
398.3
370.2
334.5
379.8



200 poise 
1667
1713
1682
1710
1723
1697



400 poise 
1598
1641
1614
1639
1656
1626



35000 poise
1286
1313
1307
1315
1339
1303


Gradient boat

62
63
64
65
66
67



internal
1205
1220
1220
1235
1265
1190



internal viscosity
192829.9
233272.2
228564.1
174834.9
155589.2
384607.5



T(35 kp) - T(liq)
81
93
87
80
74
113






Example
68
69
70
71
72
73






SiO2
71.76
72.75
70.78
71.47
72.9
71.8



Al2O3
11.26
11.42
11.85
11.87
11.69
11.49



B2O3
0
0
0.87
0
0
0



MgO
5.34
5.07
4.97
5.54
4.83
5.61



CaO
5.75
5.34
5.77
5.52
5.25
5.48



SrO
1.52
0.63
1.47
1.23
1.37
1.44



BaO
4.18
4.63
4.12
4.2
3.83
3.98



SnO2
0.16
0.11
0.14
0.11
0.12
0.16



Fe2O3
0.02
0.02
0.02
0.02
0.01
0.02



ZrO2
0.02
0.02
0.02
0.03
0
0.02



RO/Al2O3
1.49
1.37
1.38
1.39
1.31
1.44



(RO − Al2O3)/(1 − B2O3/100)
5.53
4.25
4.52
4.62
3.59
5.02



(SiO2 + Al2O3)/(1 − B2O3/100)
83.02
84.17
83.36
83.34
84.59
83.29



MgO/(MgO + CaO + SrO + BaO)
0.32
0.32
0.3
0.34
0.32
0.34


Properties

68
69
70
71
72
73



Strain
751
761
742
757
765
755



Anneal
805
815
797
810
819
808



Soft (ppv)
1046
1058.3
1040.1
1047.9

1048



CTE (disk)
39.5
37.3
38.7
37.8
36.1
38.6



Density
2.641
2.627
2.632
2.637
2.6
2.631



Young's modulus

12.013

12.237
12.124




specific modulus

31.5

32
32.2



Viscosity

68
69
70
71
72
73



A
−3.1715
−2.639
−2.8291
−2.87
−2.887
−3.2947



B
7306.29
6448.7
6603.21
6677.3
6946
7613.94



To
355.18
421.2
398.09
404.8
391.2
333.99



200 poise 
1690
1727
1685
1696
1730
1695



400 poise 
1621
1652
1614
1625
1657
1625



35000 poise
1302
1319
1294
1305
1326
1305


Gradient boat

68
69
70
71
72
73



internal
1200
1200
1180
1230
1210
1210



internal viscosity
299805.3
437827.5
412928.1
166623.1
394590
249409.6



T(35 kp) - T(liq)
102
119
114
75
116
95






Example
74
75
76
77
78
79






SiO2
72.39
73.19
72.74
71.85
71.4
71.79



Al2O3
12.32
11.54
11.38
10.79
11.71
11.53



B2O3
0.5
0
0
0
1.55
1.55



MgO
4.68
4.81
5.18
5.44
4.86
4.8



CaO
5.03
5.19
5.25
5.89
5.38
5.3



SrO
1.28
1.34
0.04
1.55
1.93
1.9



BaO
3.65
3.79
5.26
4.27
3.05
3



SnO2
0.13
0.12
0.11
0.16
0.12
0.12



Fe2O3
0.02
0.01
0.02
0.02
0.01
0.01



ZrO2
0
0
0.02
0.02
0
0



RO/Al2O3
1.19
1.31
1.38
1.59
1.3
1.3



(RO − Al2O3)/(1 − B2O3/100)
2.33
3.59
4.35
6.36
3.57
3.52



(SiO2 + Al2O3)/(1 − B2O3/100)
85.14
84.73
84.12
82.64
84.42
84.63



MgO/(MgO + CaO + SrO + BaO)
0.32
0.32
0.33
0.32
0.32
0.32


Properties

74
75
76
77
78
79



Strain
762
770
760
748
743
742



Anneal
817
822
814
801
797
796



Soft (ppv)
1060.3
1068.8
1058.4
1043
1040
1041.7



CTE (disk)
35.8
35.7
36.5
39.8
35.6
34.9



Density
2.596
2.6
2.63
2.645
2.586
2.584



Young's modulus
12.046
12.039
11.954

11.937
11.918



specific modulus
32
31.9
31.3

31.8
31.8


Viscosity

74
75
76
77
78
79



A
−3.115
−3.715
−3.007
−3.2794
−3.16
−3.089



B
7142
8889.8
7290.9
7568.49
7253.8
7373



To
393.1
251
346.7
329.91
358.9
332.6



200 poise 
1712
1729
1720
1686
1687
1700



400 poise 
1642
1658
1647
1617
1618
1628



35000 poise
1326
1327
1312
1297
1300
1299


Gradient boat

74
75
76
77
78
79



internal
1230
1235
1195
1205
1230
1220



internal viscosity
262346.3
208617
387007
234106.4
146951
165783.7



T(35 kp) - T(liq)
96
92
117
92
70
79






Example
80
81
82
83
84
85






SiO2
72.18
73.58
72.47
72.1
71.96
71.97



Al2O3
12.2
11.77
11.46
12.05
12.02
11.58



B2O3
0
0.5
0
0
0
0.84



MgO
4.91
4.48
5.34
5.47
4.98
4.68



CaO
5.52
4.81
5.3
5.16
5.23
5.47



SrO
2.07
1.22
0.37
1.34
2.15
1.39



BaO
2.96
3.49
4.9
3.75
3.49
3.9



SnO2
0.12
0.13
0.11
0.1
0.12
0.14



Fe2O3
0.02
0.02
0.02
0.01
0.02
0.02



ZrO2
0.02
0
0.02
0.02
0.03
0.02



RO/Al2O3
1.27
1.19
1.39
1.3
1.32
1.33



(RO − Al2O3)/(1 − B2O3/100)
3.26
2.24
4.45
3.67
3.83
3.89



(SiO2 + Al2O3)/(1 − B2O3/100)
84.38
85.78
83.93
84.15
83.98
84.26



MgO/(MgO + CaO + SrO + BaO)
0.32
0.32
0.34
0.35
0.31
0.3


Properties

80
81
82
83
84
85



Strain
767
766
761
764
766
748



Anneal
821
822
815
817
819
801



Soft (ppv)
1059
1073.2
1056.3
1046
1059.6
1050.8



CTE (disk)
35.7
33.7
37.3
37.3
37.1
38.6



Density
2.599
2.577
2.62
2.613
2.616
2.613



Young's modulus
12.162
11.981
11.948

12.202




specific modulus
32.3
32.1
31.4

32.2



Viscosity

80
81
82
83
84
85



A
−2.943
−3.293
−3.344
−2.967
−3.087
−2.6835



B
6934.4
7631.6
7736.8
6855.99 
7170.9 
6479.42



To
388.4
359.5
336.1
403.9
369.3
412.79



200 poise 
1711
1724
1707
1705
1700
1713



400 poise 
1639
1654
1637
1635
1630
1639



35000 poise
1315
1333
1317
1317
1309
1309


Gradient boat

80
81
82
83
84
85



internal
1240
1245
1220
1220
1220
1195



internal viscosity
158412.7
211547.4
256464 
271593.3
219994.1
398087.8



T(35 kp) - T(liq)
75
88
97
97
89
114






Example
86
87
88
89
90
91






SiO2
71.31
71.28
71.2
72.21
71.69
72.77



Al2O3
11.86
12.27
12.13
11.56
11.89
11.38



B2O3
1.35
1.72
0.5
0
1.25
0



MgO
5.21
4.19
6.03
5.43
4.85
5.56



CaO
5.35
5.34
5.28
5.36
5.11
3.86



SrO
2.01
1.29
2.17
0.74
1.45
3.09



BaO
2.76
3.76
2.52
4.55
3.6
3.19



SnO2
0.12
0.12
0.12
0.11
0.12
0.11



Fe2O3
0.02
0.02
0.02
0.02
0.03
0.02



ZrO2
0.01
0.01
0.03
0.02
0
0.02



RO/Al2O3
1.29
1.19
1.32
1.39
1.26
1.38



(RO − Al2O3)/(1 − B2O3/100)
3.52
2.35
3.89
4.52
3.16
4.32



(SiO2 + Al2O3)/(1 − B2O3/100)
84.31
85.01
83.75
83.77
84.64
84.15



MgO/(MgO + CaO + SrO + BaO)
0.34
0.29
0.38
0.34
0.32
0.35


Properties

86
87
88
89
90
91



Strain
745
743
750
759
740
762



Anneal
799
798
804
813
794
816



Soft (ppv)
1039.6
1044.9
1040
1055.3
1038.7
1059



CTE (disk)
35.7
34.8
37.7
36.2
36.2
36.3



Density
2.583
2.597
2.6
2.627
2.61
2.615



Young's modulus
12.246
11.874

12.085
12.033
12.076



specific modulus
32.7
31.5

31.7
31.8
31.8


Viscosity

86
87
88
89
90
91



A
−2.812
−3.025 
−3.1872
−3.18
−2.898
−3.169



B
6516.6
7014.5
7081.73
7409.1
6712.1
7419



To
413
375.5
377.63
357.2
392
360



200 poise 
1688
1693
1668
1709
1683
1716



400 poise 
1617
1622
1601
1639
1612
1646



35000 poise
1299
1302
1294
1316
1294
1322


Gradient boat

86
87
88
89
90
91



internal
1205
1185
1210
1220
1210
1225



internal viscosity
260633.5
436742.5 
209272
255431.2
203002.4
255787.1



T(35 kp) - T(liq)
94
117
84
96
84
97






Example
92
93
94
95
96
97






SiO2
72.39
71.74
71.2
73.78
71.65
72.79



Al2O3
11.55
11.37
11.91
11.88
12.18
12.14



B2O3
0
0
1.65
0.63
0
0.5



MgO
5.05
5.83
4.81
4.3
6.07
4.62



CaO
5.48
5.48
5.58
4.64
5.49
4.95



SrO
1.66
1.08
2.03
1.16
2.34
1.26



BaO
3.72
4.32
2.69
3.46
2.11
3.59



SnO2
0.11
0.11
0.12
0.11
0.12
0.13



Fe2O3
0.02
0.04
0.01
0.01
0.02
0.02



ZrO2
0.01
0.03
0
0.02
0.02
0



RO/Al2O3
1.38
1.47
1.27
1.14
1.31
1.19



(RO − Al2O3)/(1 − B2O3/100)
4.36
5.34
3.25
1.69
3.83
2.29



(SiO2 + Al2O3)/(1 − B2O3/100)
83.94
83.11
84.5
86.2
83.83
85.36



MgO/(MgO + CaO + SrO + BaO)
0.32
0.35
0.32
0.32
0.38
0.32


Properties

92
93
94
95
96
97



Strain
760
753
741
763
765
764



Anneal
813
806
796
820
817
819



Soft (ppv)
1055.4
1044.7
1039.2
1070.2
1049.5
1062.7



CTE (disk)
36.9
37.8
36
34.3
36.1
34.9



Density
2.622
2.637
2.578
2.574
2.591
2.589



Young's modulus
12.164
12.119
11.97
11.988
12.446
12.04



specific modulus
32
31.7
32
32.1
33.1
32.1


Viscosity

92
93
94
95
96
97



A
−3.214
−3.086
−2.964
−2.597
−3.309
−3.074



B
7473.4
7079.3
6900.9
6453.9
7354.2
7152.6



To
354.4
383.5
376.5
432.9
364.9
386.7



200 poise 
1709
1698
1687
1751
1676
1717



400 poise 
1639
1628
1616
1674
1609
1647



35000 poise
1318
1311
1296
1337
1301
1326


Gradient boat

92
93
94
95
96
97



internal
1215
1210
1210
1240
1225
1230



internal viscosity
295081.1
301575.6
206739.8
250845.8
174341.6
255669.6



T(35 kp) - T(liq)
103
101
86
97
76
96






Example
98
99
100
101
102
103






SiO2
72.33
71.5
71.5
71.06
70.87
71.13



Al2O3
11.69
11.78
11.75
11.98
11.75
11.2



B2O3
0
0.85
1.99
1.85
1.31
0.69



MgO
5.26
4.77
4.2
4.45
5.53
5.84



CaO
5.34
5.55
5.28
5.77
5.4
5.52



SrO
1.24
1.41
2.65
1.7
1.77
1.04



BaO
4
3.96
2.49
3.03
3.22
4.41



SnO2
0.11
0.14
0.12
0.12
0.11
0.11



Fe2O3
0.01
0.02
0.01
0.01
0.02
0.05



ZrO2
0.02
0.02
0.01
0.01
0.02
0.02



RO/Al2O3
1.36
1.33
1.24
1.25
1.35
1.5



(RO − Al2O3)/(1 − B2O3/100)
4.15
3.94
2.93
3.03
4.23
5.65



(SiO2 + Al2O3)/(1 − B2O3/100)
84.02
83.99
84.94
84.61
83.72
82.9



MgO/(MgO + CaO + SrO + BaO)
0.33
0.3
0.29
0.3
0.35
0.35


Properties

98
99
100
101
102
103



Strain
763
748
737
740
742
741



Anneal
816
800
793
794
794
793



Soft (ppv)
1056.4
1046.7
1037.9
1037.3
1032.8
1031.1



CTE (disk)
36.2
37.5
35.9
36
35.9
34.9



Density
2.621
2.62
2.574
2.58
2.601
2.633



Young's modulus
12.229

11.87
12.06
12.082
12.053



specific modulus
32.2

31.8
32.2
32
31.6


Viscosity

98
99
100
101
102
103



A
−2.965
−2.7111 
−2.963
−2.719
−2.756
−3.099



B
6904.9
6461.74
6934
6302.2
6435.6
7055.7



To
402
416
373.1
430.5
406.1
365.4



200 poise 
1713
1705
1690
1686
1679
1672



400 poise 
1642
1632
1619
1615
1607
1603



35000 poise
1322
1307
1297
1298
1288
1289


Gradient boat

98
99
100
101
102
103



internal
1220
1190
1200
1200
1190
1185



internal viscosity
299362.9
433911.6
264567.4
295796.8
284263.2
323378.8



T(35 kp) - T(liq)
102
117
97
98
98
104






Example
104
105
106
107
108
109






SiO2
71.52
73.74
71.43
73.55
72.18
71.34



Al2O3
12.44
11.82
11.43
11.85
11.86
10.98



B2O3
1.72
0
0
0.3
0
0



MgO
4.08
4.54
6.1
4.5
5.52
5.56



CaO
5.19
4.9
5.44
4.83
5.39
5.99



SrO
1.25
1.24
1.43
1.23
1.59
1.58



BaO
3.65
3.62
3.96
3.59
3.3
4.35



SnO2
0.12
0.11
0.16
0.11
0.11
0.16



Fe2O3
0.01
0.01
0.02
0.01
0.02
0.02



ZrO2
0.02
0.02
0.02
0.02
0.02
0.02



RO/Al2O3
1.14
1.21
1.48
1.19
1.33
1.59



(RO − Al2O3)/(1 − B2O3/100)
1.76
2.48
5.5
2.31
3.94
6.5



(SiO2 + Al2O3)/(1 − B2O3/100)
85.43
85.56
82.86
85.66
84.04
82.32



MgO/(MgO + CaO + SrO + BaO)
0.29
0.32
0.36
0.32
0.35
0.32


Properties

104
105
106
107
108
109



Strain
745
770
753
768
764
750



Anneal
798
825
806
823
816
802



Soft (ppv)

1071.1
1041
1071.7
1050.7
1039



CTE (disk)
36.4
35.9
38.2
35.7
36.7
40.1



Density

2.59
2.633
2.589
2.616
2.652



Young's modulus

12.047

12.037
12.292




specific modulus

32.1

32.1
32.4



Viscosity

104
105
106
107
108
109



A
−3.3669
−3.093
−3.1455
−2.724
−2.405
−3.1246



B
7769.3
7315.2
7160.06
6678.5
5903.2
7195.68



To
322.18
375.6
372.38
418.1
457.3
356.84



200 poise 
1693
1732
1687
1747
1712
1683



400 poise 
1624
1660
1618
1672
1636
1613



35000 poise
1304
1333
1304
1337
1307
1295


Gradient boat

104
105
106
107
108
109



internal
1190
1235
1200
1250
1210
1190



internal viscosity
385268 
262412.9
320542.7
201376.2
273967.9
325096.6



T(35 kp) - T(liq)
114
98
104
87
97
105






Example
110
111
112
113
114
115






SiO2
72.75
73.6
72.81
72.64
72.5
71.12



Al2O3
11.41
11.74
11.38
11.37
11.87
11.82



B2O3
0
0
0
0
0
2.01



MgO
4.92
4.62
4.93
5.27
4.91
4.45



CaO
5.54
4.98
5.46
5.07
5.33
5.93



SrO
1.17
1.29
1.37
3.3
1.39
2.25



BaO
4.06
3.64
3.9
2.2
3.87
2.26



SnO2
0.11
0.12
0.11
0.11
0.12
0.12



Fe2O3
0.02
0.01
0.02
0.02
0.01
0.02



ZrO2
0.02
0
0.02
0.02
0
0.02



RO/Al2O3
1.38
1.24
1.38
1.39
1.31
1.26



(RO − Al2O3)/(1 − B2O3/100)
4.28
2.79
4.28
4.47
3.63
3.13



(SiO2 + Al2O3)/(1 − B2O3/100)
84.16
85.34
84.19
84.01
84.37
84.64



MgO/(MgO + CaO + SrO + BaO)
0.31
0.32
0.31
0.33
0.32
0.3


Properties

110
111
112
113
114
115



Strain
760
772
760
760
765
735



Anneal
814
826
815
815
820
791



Soft (ppv)
1056.3
1071
1054.1
1056.4

1033.5



CTE (disk)
36.7
35.7
36.6
36.2
36
36.3



Density
2.622
2.599
2.62
2.599
2.601
2.568



Young's modulus
12.073
12.095
12.127
12.228
12.146
11.956



specific modulus
31.7
32.1
31.9
32.4
32.2
32.1


Viscosity

110
111
112
113
114
115



A
−3.431
−3.385
−2.954
−3.608
−3.184
−3.086



B
7862.3
7779.3
6950.9
8438.4
7438.8
7014.9



To
335
357.4
394.2
282.4
357
375.4



200 poise 
1707
1726
1717
1710
1713
1678



400 poise 
1638
1657
1645
1641
1643
1609



35000 poise
1321
1339
1321
1318
1320
1295


Gradient boat

110
111
112
113
114
115



internal
1210
1250
1210
1240
1210
1210



internal viscosity
358497.2
213956.8
368424.2
159966.9
344152
208499.1



T(35 kp) - T(liq)
111
89
111
78
110
85






Example
116
117
118
119
120
121






SiO2
72.29
72.71
71.88
71.32
72.33
71.88



Al2O3
11.87
11.48
11.47
11.64
11.55
11.97



B2O3
0
0
0
0.85
0
0



MgO
4.92
4.95
5.66
4.87
5.05
5.74



CaO
5.67
5.39
5.46
5.67
5.49
5.36



SrO
2.62
1.46
1.12
1.44
1.52
1.89



BaO
2.46
3.82
4.24
4.05
3.9
3



SnO2
0.12
0.15
0.11
0.14
0.11
0.11



Fe2O3
0.02
0.02
0.03
0.01
0.02
0.02



ZrO2
0.03
0.02
0.02
0
0.02
0.02



RO/Al2O3
1.32
1.36
1.44
1.38
1.38
1.34



(RO − Al2O3)/(1 − B2O3/100)
3.8
4.14
5.01
4.43
4.41
4.02



(SiO2 + Al2O3)/(1 − B2O3/100)
84.16
84.19
83.35
83.67
83.88
83.85



MgO/(MgO + CaO + SrO + BaO)
0.31
0.32
0.34
0.3
0.32
0.36


Properties

116
117
118
119
120
121



Strain
763
763
757
744
763
762



Anneal
818
817
810
798
814
814



Soft (ppv)
1057.3
1055.8
1049.1
1042.4
1055.7
1051.6



CTE (disk)
36
36.6
38.3
38.4
37.2
35.7



Density
2.598
2.613
2.634
2.624
2.623
2.608



Young's modulus
12.197
12.08
12.094

12.118
12.297



specific modulus
32.4
31.9
31.7

31.9
32.5


Viscosity

116
117
118
119
120
121



A
−2.921
−3.036
−3.121
−2.745
−3.031
−2.606



B
6826.5
7156.8
7213.1 
6495.63
7108.6
6152.6



To
395.7
373.8
367.2
406.26
378.9
446



200 poise 
1703
1715
1698
1694
1712
1700



400 poise 
1632
1643
1628
1621
1641
1627



35000 poise
1310
1318
1308
1297
1317
1306


Gradient boat

116
117
118
119
120
121



internal
1240
1210
1220
1185
1200
1225



internal viscosity
146014.6
333210 
217339.1
394643.6
423068.6
195918.1



T(35 kp) - T(liq)
70
108
88
112
117
81









Various modifications and variations can be made to the materials, methods, and articles described herein. Other aspects of the materials, methods, and articles described herein will be apparent from consideration of the specification and practice of the materials, methods, and articles disclosed herein. It is intended that the specification and examples be considered as exemplary.

## Claims

1. A glass comprising in mol percent on an oxide basis:


70≦SiO2≦74.5



10.5≦Al2O3≦13.5



0≦B2O3≦2.5



3≦MgO≦7



3≦CaO≦7



0≦SrO≦4



1.5≦BaO≦6



0≦SnO2≦0.3



0≦CeO2≦0.3



0≦As2O3≦0.5



0.01≦Fe2O3≦0.08



F+Cl+Br≦0.4


wherein


(SiO2+Al2O3)/(1−B2O3/100)=86.97−0.713*(RO—Al2O3)/(1−B2O3/100)±0.8


where:
(i) RO=MgO+CaO+SrO +BaO, and
(ii) SiO2, Al2O3, B2O3, MgO, CaO, SrO and BaO represent the mol percents of the representative oxide components.

2. The glass of claim 1 wherein the glass has an anneal point greater than 785° C.

3. The glass of claim 1 wherein the glass has an anneal point greater than 800° C.

4. The glass of claim 1 wherein the glass comprises less than 0.05% by weight of As2O3, Sb2O3 or combinations thereof.

5. The glass of claim 1 wherein the glass comprises less than 0.02% by weight of F, Cl, Br or combinations thereof.

6. The glass of claim 1 wherein the glass comprises less than about 1000 ppm of alkali oxides.

7. The glass of claim 1 wherein the glass comprises up to about 500 ppm ZrO2.

8. The glass of claim 1 wherein


0.29≦MgO/RO≦0.39.

9. The glass of claim 1 wherein in mol percent on an oxide basis the glass satisfies the relationship:


0≦B2O3≦1.0.

10. The glass of claim 1 wherein in mol percent on an oxide basis the glass satisfies the relationship:


0≦B2O3≦0.5.

11. The glass of claim 1 wherein the glass is essentially free of B2O3.

12. The glass of claim 1 wherein


1.05≦RO/Al2O3≦1.7.

13. The glass of claim 1 wherein


0.2≦MgO/RO≦0.45.

14. A glass comprising in mol percent on an oxide basis:


70≦SiO2≦74.5



10.5≦Al2O3≦13.5



3≦MgO≦7



3≦CaO≦7



0≦SrO≦4



1.5≦BaO≦6



0≦SnO2≦0.3



0≦CeO2≦0.3



0≦As2O3≦0.5



0≦Sb2O3≦0.5



0.01≦Fe2O3≦0.08



F+Cl+Br≦0.4


wherein
(a) 1.05≦RO/Al2O3≦1.7;
(b) 0.2≦MgO/RO≦0.45; and
(c) the glass is boron free;

where:
(i) RO=MgO+CaO+SrO+BaO, and
(ii) SiO2, Al2O3, B2O3, MgO, CaO, SrO and BaO represent the mol percents of the representative oxide components.

15. The glass of claim 14 wherein the glass comprises less than 0.05% by weight of As2O3, Sb2O3 or combinations thereof.

16. The glass of claim 14 wherein the glass comprises less than about 1000 ppm of alkali oxides.

17. The glass of claim 14 wherein the glass comprises up to about 500 ppm ZrO2.

18. The glass of claim 14 wherein


0.29≦MgO/RO≦0.39.

19. The glass of claim 14 wherein:


(SiO2+Al2O3)/(1−B2O3/100)=86.97−0.713*(RO—Al2O3)/(1−B2O3/100)±0.8.

20. The glass of claim 14 wherein the glass has a liquidus viscosity of at least 130,000 poise.