Patent Description:
Processes for preparing Mn<NUM>+-doped complex fluoride phosphors with improved color stability are described in <CIT> and other patents and patent applications assigned to General Electric Company or Current. Yet there remains a need for even further improvements in stability and dispersibility of the complex fluoride phosphors, while maintaining excellent performance in lighting and display applications. <CIT> discloses a fluoride phosphor and a light emitting device using the same, and a method of manufacturing the fluoride phosphor. <CIT> discloses a coated manganese doped hexafluorosilicate phosphor, a lighting unit comprising such phosphor, and a method for the preparation of such phosphor.

Briefly, in one aspect, the present invention relates to a process for producing a stabilized Mn+<NUM> doped phosphor in solid form according to the annexed claims. Such process may include combining a) a solution comprising at least one substance selected from the group consisting of: K2HPO4, an aluminum phosphate, oxalic acid, or a combination thereof, with b) a Mn+<NUM> doped phosphor of formula I in solid form, where formula I may be: Ax [MFy]:Mn+<NUM>. The process can further include isolating the stabilized Mn<NUM>+ doped phosphor in solid form. In formula I, A may be Li, Na, K, Rb, Cs, or a combination thereof. In formula I, M may be Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb,
Ta, Bi, Gd, or a combination thereof. In formula I, x is the absolute value of the charge of the [MFy] ion and y is <NUM>, <NUM> or <NUM>.

Another aspect of the present invention relates to a composition which includes a) at least one substance selected from the group consisting of: K<NUM>HPO<NUM>, an aluminum phosphate, oxalic acid, or a combination thereof, and b) a Mn<NUM>+ doped phosphor of formula I, where formula I is: Ax [MFy]:Mn<NUM>+. In formula I, A may be Li, Na, K, Rb, Cs, or a combination thereof. In formula I, M may be Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof. In formula I, x is the absolute value of the charge of the [MFy] ion and y is <NUM>, <NUM> or <NUM>.

Yet another aspect of the present invention is directed to a phosphor composition including phosphor particles and, on their surfaces, at least one surface composition selected from the group consisting of: <NUM>) a composition including a phosphorus-containing moiety and a carbon-containing moiety; <NUM>) a composition including a phosphorus-containing moiety and a metal fluoride; <NUM>) a composition including a phosphorus-containing moiety and a carbon-containing moiety and a metal fluoride; and <NUM>) a composition comprising the phosphorus-containing moiety free of an alkyl phosphate compound, where the phosphor particles comprise a Mn<NUM>+ doped phosphor of formula I;.

In one aspect, the present invention relates to processes for producing a stabilized Mn<NUM>+ doped phosphor in solid form. Such processes may include combining a) a solution including at least one substance selected from the group consisting of: K<NUM>HPO4, an aluminum phosphate, oxalic acid, or a combination thereof, with b) a Mn<NUM>+ doped phosphor of formula I in solid form. In an embodiment, the amount of the substance mentioned above is <NUM>-<NUM>% by weight relative to the amount of the Mn<NUM>+ doped phosphor of formula I, such as <NUM>% to <NUM>%, and <NUM>% to <NUM>%.

In another aspect the present invention relates to a composition which includes a) at least one substance selected from the group consisting of: K<NUM>HPO4, an aluminum phosphate, oxalic acid, or a combination thereof, and b) a Mn<NUM>+ doped phosphor of formula I.

The Mn<NUM>+ doped phosphors of formula I are complex fluoride materials, or coordination compounds, containing at least one coordination center surrounded by fluoride ions acting as ligands, and charge-compensated by counter ions as necessary. For example, in K<NUM>SiF<NUM>:Mn<NUM>+, the coordination center is Si and the counterion is K. Complex fluorides are occasionally written as a combination of simple, binary fluorides but such a representation does not indicate the coordination number for the ligands around the coordination center. The square brackets (occasionally omitted for simplicity) indicate that the complex ion they encompass is a new chemical species, different from the simple fluoride ion. The activator ion (Mn<NUM>+) also acts as a coordination center, substituting part of the centers of the host lattice, for example, Si. The host lattice (including the counter ions) may further modify the excitation and emission properties of the activator ion.

In particular embodiments, the coordination center of the phosphor, that is, M in formula I, is Si, Ge, Sn, Ti, Zr, or a combination thereof. More particularly, the coordination center may be Si, Ge, Ti, or a combination thereof. The counterion, or A in formula I, may be Na, K, Rb, Cs, or a combination thereof, more particularly K. Examples of phosphors of formula I include K<NUM>[SiF<NUM>]:Mn<NUM>+, K<NUM>[TiF<NUM>]:Mn<NUM>+, K<NUM>[SnF<NUM>]:Mn<NUM>+, Cs<NUM>[TiF<NUM>]:Mn<NUM>+, Rb<NUM>[TiF<NUM>]:Mn<NUM>+, Cs<NUM>[SiF<NUM>]:Mn<NUM>+, Rb<NUM>[SiF<NUM>]:Mn<NUM>+, Na<NUM>[TiF<NUM>]:Mn<NUM>+, Na<NUM>[ZrF<NUM>]:Mn<NUM>+, Ka[ZrF<NUM>]:Mn<NUM>+, K<NUM>[BiF<NUM>]:Mn<NUM>+ K<NUM>[YF<NUM>]:Mn<NUM>+, K<NUM>[LaF<NUM>]:Mn<NUM>+, K<NUM>[GdF<NUM>]:Mn<NUM>+, K<NUM>[NbF<NUM>]:Mn<NUM>+, K<NUM>[TaF<NUM>]:Mn<NUM>+. In particular embodiments, the phosphor of formula I is K<NUM>SiF<NUM>:Mn<NUM>+.

The amount of manganese in the Mn<NUM>+ doped phosphors of formula I may range from about <NUM> mol% based on the total number of moles of Mn and M (such as Si) (about <NUM> wt% based on total phosphor weight) to about <NUM> mol% (about <NUM> wt%), particularly from about <NUM> mol% (about <NUM> wt%) to about <NUM> mol% (about <NUM> wt%). In particular embodiments, the amount of manganese may range from about <NUM> mol% (about <NUM> wt%) to <NUM> mol% (about <NUM> wt%), or from about <NUM> mol% to <NUM> mol% (about <NUM> wt%), or from about <NUM> mol% to <NUM> mol% (about <NUM> wt%), or from about <NUM> mol% to about <NUM> mol% (about <NUM> wt%), or from about <NUM> mol% to <NUM> mol% (about <NUM> wt%), or from about <NUM> mol% to about <NUM> mol% (about <NUM> wt%).

The Mn<NUM>+ doped phosphor of formula I may be annealed to improve stability as described in <CIT> prior to combination with K<NUM>HP04, an aluminum phosphate, oxalic acid, phosphoric acid, a surfactant, a chelating agent, or a combination thereof. In such embodiments, the product phosphor is held at an elevated temperature, while in contact with an atmosphere containing a fluorine-containing oxidizing agent. The fluorine-containing oxidizing agent may be F<NUM>, HF, SF<NUM>, BrF<NUM>, N <NUM>HF<NUM>, NH<NUM>F, KF, AlF<NUM>, SbF<NUM>,
CIF3, BrF<NUM>, KrF<NUM>, XeF<NUM>, XeF<NUM>, XeF<NUM>, NF<NUM>, SiF<NUM>, PbF<NUM>, ZnF<NUM>, SnF<NUM>, CdF<NUM>, a CrC<NUM> fluorocarbon, or a combination thereof. Examples of suitable fluorocarbons include CF<NUM>, C<NUM>F<NUM>, C<NUM>Fg, CHF<NUM>, CF<NUM>CH<NUM>F, and CF<NUM>CHF. In particular embodiments, the fluorine-containing oxidizing agent is F<NUM>. The amount of oxidizing agent in the atmosphere may be varied to obtain a color stable phosphor, particularly in conjunction with variation of time and temperature. Where the fluorine-containing oxidizing agent is F<NUM>, the atmosphere may include at least <NUM>% F<NUM>, although a lower concentration may be effective in some embodiments. In particular the atmosphere may include at least <NUM>% F<NUM> and more particularly at least <NUM>% F<NUM>. The atmosphere may additionally include nitrogen, helium, neon, argon, krypton, xenon, in any combination with the fluorine-containing oxidizing agent. In particular embodiments, the atmosphere is composed of about <NUM>% F<NUM> and about <NUM>% nitrogen.

The temperature at which the phosphor is contacted with the fluorine-containing oxidizing agent at an elevated temperature may be a temperature in the range from about <NUM> to about <NUM>, particularly from about <NUM> to about <NUM> during contact, and in some embodiments from about <NUM> to about <NUM>. The phosphor is contacted with the oxidizing agent for a period of time sufficient to convert it to a color stable phosphor. Time and temperature are interrelated, and may be adjusted together, for example, increasing time while reducing temperature, or increasing temperature while reducing time. In particular embodiments, the time is at least one hour, particularly at least four hours, more particularly at least six hours, and most particularly at least eight hours. After holding at the elevated temperature for the desired period of time, the temperature in the furnace may be reduced at a controlled rate while maintaining the oxidizing atmosphere for an initial cooling period. The temperature may be reduced to about <NUM> with controlled cooling, then control may be discontinued if desired.

The manner of contacting the phosphor with the fluorine-containing oxidizing agent is not critical and may be accomplished in any way sufficient to convert the phosphor to a color stable phosphor having the desired properties. In some embodiments, the chamber containing the phosphor may be dosed and then sealed such that an overpressure develops as the chamber is heated, and in others, the fluorine and nitrogen mixture is flowed throughout the anneal process ensuring a more uniform pressure. In some embodiments, an additional dose of the fluorine-containing oxidizing agent may be introduced after a period of time.

The annealed phosphor may be treated with a saturated or nearly saturated solution of a composition of formula II in aqueous hydrofluoric acid.

A nearly saturated solution contains about <NUM>-<NUM>% excess aqueous HF added to a saturated solution. The concentration of HF in the solution ranges from about <NUM>% (wt/vol) to about <NUM>% (wt/vol), in particular from about <NUM>% (wt/vol) to about <NUM>% (wt/vol). Less concentrated solutions may result in reduced performance of the phosphor. The amount of treatment solution used ranges from about <NUM>-<NUM>/g product, particularly about <NUM>-<NUM>/g product, more particularly about <NUM>-<NUM>/g product. The treated annealed phosphor may be isolated by filtration, washed with solvents such as acetic acid and acetone to remove contaminants and traces of water, and stored under nitrogen.

After treatment, the phosphor may optionally be contacted with a fluorine-containing oxidizing agent in gaseous form at a second, lower temperature. The second temperature may be the same as the first temperature, or may be less than the first, ranging up to and including <NUM>, particularly up to and including <NUM>, and more particularly, up to and including <NUM>. The time for contacting with the oxidizing agent may be at least one hour, particularly at least four hours, more particularly at least six hours, and most particularly at least eight hours. In a specific embodiment, the phosphor is contacted with the oxidizing agent for a period of at least eight hours at a temperature of about <NUM>. The oxidizing agent may be the same as or different from that used in the first annealing step. In particular embodiments, the fluorine-containing oxidizing agent is F<NUM>. More
particularly, the atmosphere may include at least <NUM>% F<NUM>. The phosphor may be contained in a vessel having a non-metallic surface in order to reduce contamination of the phosphor with metals.

The Mn<NUM>+ doped phosphors of formula I may have a core-shell structure composed of a core which includes the phosphor of formula I and a manganese-free shell or composite coating disposed on the core. The manganese-free composite coating includes a compound of formula III and a metal fluoride.

The metal fluoride may be one or more of the following: calcium fluoride, strontium fluoride, magnesium fluoride, yttrium fluoride, scandium fluoride, and lanthanum fluoride. In particular embodiments, the phosphor of formula I is K<NUM>[SiF<NUM>]:Mn<NUM>+. The metal fluoride can be, in an embodiment, MgF<NUM>. The core-shell Mn<NUM>+ doped phosphors of formula I and methods for preparing them are described in <CIT>. As stated above, the Mn<NUM>+ doped phosphors of formula I may be combined with (or form part of a composition which is) a solution or suspension that includes one or more of the following substances: K<NUM>HPO<NUM>, an aluminum phosphate, oxalic acid, phosphoric acid, a surfactant, a chelating agent, or a combination thereof. K<NUM>HPO<NUM>, an aluminum phosphate, oxalic acid, or a combination thereof shall be referred to herein as Substance. The weight ratio of the phosphor to the Substance may be from <NUM>: <NUM> to <NUM> : <NUM> and, more preferably, is from <NUM>: <NUM> to <NUM>: <NUM>. Examples of suitable chelating agent include, but are not limited to, ammonium citrate, potassium citrate, iminodiacetic acid (IDA), and ethylenediaminetetraacetic acid (EDTA). The surfactant may be nonionic, anionic, or cationic, or a mixture thereof. Examples of suitable surfactants include, but are not limited to, aliphatic amines, fluorocarbon surfactants, stearic acid and stearate salts, and oleic acid and oleate salts. Suitable nonionic surfactants include polyoxyethylene sorbitan fatty acid esters, commercially available under the TWEEN<NUM>, brand, fluorocarbon
polyoxyethylene nonylphenol ethers. The surfactants (or other surface agents) can be one or more of polyoxyethylene octyl phenyl ether, potassium oleate, polyoxyethylene-polyoxypropylene block copolymer (such as that sold as Pluronic F-<NUM>); polyoxyethylene (<NUM>) sorbitan monolaurate (such as that sold as Tween <NUM>), poly(acrylic acid sodium salt), potassium sorbate, sorbitan monooleate (such as that sold as Span <NUM>), and sodium hexametaphosphate. Additional examples of suitable surfactants are described in <CIT>, <CIT> and <NPL>. In particular, the substance may include K2HPO4. As stated above, the substance can also include a surfactant. The substance can include both the surfactant and K2HPO4.

The solution that the surfactant forms part of may include one or more of the following solvents: <NUM>-octadecene, isonorbomyl acrylate, water, and propylene glycol monomethyl ether acetate. It is noted that the organic solutions of the present invention may include a minor amount of water. For example, there may be water present in the propylene glycol monomethyl ether acetate (less than <NUM>% by Karl Fischer), and also a minor amount of water in the potassium oleate. If the surfactant is part of an aqueous solution, such aqueous solution can also include H2O2. If H2O2 is used, this can be in a range by weight of phosphor to H2O2 of <NUM>: <NUM> to <NUM> : <NUM> and, more preferably, from <NUM>: <NUM> to <NUM>: <NUM>.

An LED package or light emitting assembly or lamp <NUM> that may be used as part of a display or lighting device or apparatus is shown in <FIG>. LED package <NUM> includes a semiconductor radiation source, shown as LED chip <NUM>, and leads <NUM> electrically attached to the LED chip. The leads <NUM> may be thin wires supported by a thicker lead frame(s) <NUM> or the leads may be self-supported electrodes and the lead frame may be omitted. The leads <NUM> provide current to LED chip <NUM> and thus cause it to emit radiation.

The lamp may include any semiconductor blue or UV light source that is capable of producing white light when its emitted radiation is directed onto the phosphor. In one embodiment, the semiconductor light source is a blue emitting LED doped with various impurities. Thus, the LED may comprise a semiconductor diode based on any suitable III-V, II-VI or IV -IV semiconductor layers and have an emission wavelength of about <NUM> to
<NUM>. In particular, the LED may contain at least one semiconductor layer comprising GaN, ZnSe or SiC. For example, the LED may comprise a nitride compound semiconductor represented by the formula Ih,Oh,Ali,N (where <NUM>< i; <NUM>< j; <NUM>< k, and i +j + k = <NUM>) and have an emission wavelength greater than about <NUM> and less than about <NUM>. In particular embodiments, the chip is a near-uv or blue emitting LED having a peak emission wavelength from about <NUM> to about <NUM>. Such LED semiconductors are known in the art. The radiation source is described herein as an LED for convenience. However, as used herein, the term is meant to encompass all semiconductor radiation sources including, e.g., semiconductor laser diodes. Further, although the general discussion of the exemplary structures of the invention discussed herein is directed toward inorganic LED based light sources, it should be understood that the LED chip may be replaced by another radiation source unless otherwise noted and that any reference to semiconductor, semiconductor LED, or LED chip is merely representative of any appropriate radiation source, including, but not limited to, organic light emitting diodes.

In LED package <NUM>, phosphor composition <NUM> is radiationally coupled to the LED chip <NUM>. Radiationally coupled means that the elements are associated with each other so radiation from one is transmitted to the other. Phosphor composition <NUM> is deposited on the LED <NUM> by any appropriate method. For example, a suspension of the phosphor(s) can be formed and applied as a phosphor layer to the LED surface. In one such method, a silicone slurry in which the phosphor particles are randomly suspended is placed around the LED. This method is merely exemplary of possible positions of phosphor composition <NUM> and LED <NUM>. Thus, phosphor composition <NUM> may be coated over or directly on the light emitting surface of the LED chip <NUM> by coating and drying the phosphor suspension over the LED chip <NUM>. In the case of a silicone-based suspension, the suspension is cured at an appropriate temperature. Both the shell <NUM> and the encapsulant <NUM> should be transparent to allow white light <NUM> to be transmitted through those elements.

In other embodiments, phosphor composition <NUM> is interspersed within the encapsulant material <NUM>, instead of being formed directly on the LED chip <NUM>. The phosphor (in the form of a powder) may be interspersed within a single region of the encapsulant material <NUM> or throughout the entire volume of the encapsulant material. Blue
light emitted by the LED chip <NUM> mixes with the light emitted by phosphor composition <NUM>, and the mixed light appears as white light. If the phosphor is to be interspersed within the material of encapsulant <NUM>, then a phosphor powder may be added to a polymer or silicone precursor, loaded around the LED chip <NUM>, and then the polymer precursor may be cured to solidify the polymer or silicone material. Other known phosphor interspersion methods may also be used, such as transfer loading.

In yet another embodiment, phosphor composition <NUM> is coated onto a surface of the shell <NUM>, instead of being formed over the LED chip <NUM>. The phosphor composition is preferably coated on the inside surface of the shell <NUM>, although the phosphor may be coated on the outside surface of the shell, if desired. Phosphor composition <NUM> may be coated on the entire surface of the shell or only a top portion of the surface of the shell. The UV/blue light emitted by the LED chip <NUM> mixes with the light emitted by phosphor composition <NUM>, and the mixed light appears as white light. Of course, the phosphor may be located in any two or all three locations or in any other suitable location, such as separately from the shell or integrated into the LED.

<FIG> illustrates a second structure of the system according to the present invention. Corresponding numbers from <FIG> (e.g. <NUM> in <FIG> and <NUM> in <FIG>) relate to corresponding structures in each of the figures, unless otherwise stated. The structure of the embodiment of <FIG> is similar to that of <FIG>, except that the phosphor composition <NUM> is interspersed within the encapsulant material <NUM>, instead of being formed directly on the LED chip <NUM>. The phosphor (in the form of a powder) may be interspersed within a single region of the encapsulant material or throughout the entire volume of the encapsulant material. Radiation (indicated by arrow <NUM>) emitted by the LED chip <NUM> mixes with the light emitted by the phosphor <NUM>, and the mixed light appears as white light <NUM>. If the phosphor is to be interspersed within the encapsulant material <NUM>, then a phosphor powder may be added to a polymer precursor and loaded around the LED chip <NUM>. The polymer or silicone precursor may then be cured to solidify the polymer or silicone. Other known phosphor interspersion methods may also be used, such as transfer molding.

<FIG> illustrates a third possible structure of the system according to the present invention. The structure of the embodiment shown in <FIG> is similar to that of <FIG>, except that the phosphor composition <NUM> is coated onto a surface of the envelope <NUM>, instead of being formed over the LED chip <NUM>. The phosphor composition <NUM> is preferably coated on the inside surface of the envelope <NUM>, although the phosphor may be coated on the outside surface of the envelope, if desired. The phosphor composition <NUM> may be coated on the entire surface of the envelope, or only a top portion of the surface of the envelope. The radiation <NUM> emitted by the LED chip <NUM> mixes with the light emitted by the phosphor composition <NUM>, and the mixed light appears as white light <NUM>. Of course, the structures of <FIG> may be combined, and the phosphor may be located in any two or all three locations, or in any other suitable location, such as separately from the envelope, or integrated into the LED.

In any of the above structures, the lamp <NUM> may also include a plurality of scattering particles (not shown), which are embedded in the encapsulant material. The scattering particles may comprise, for example, silica, alumina, zirconia, titania, zinc oxide, or a combination thereof. The scattering particles effectively scatter the directional light emitted from the LED chip, preferably with a negligible amount of absorption.

As shown in a fourth structure in <FIG>, the LED chip <NUM> may be mounted in a reflective cup <NUM>. The cup <NUM> may be made from or coated with a dielectric material, such as silica, alumina, zirconia, titania, or other dielectric powders known in the art, or be coated by a reflective metal, such as aluminum or silver. The remainder of the structure of the embodiment of <FIG> is the same as those of any of the previous figures, and can include two leads <NUM>, a conducting wire <NUM>, and an encapsulant material <NUM>. The reflective cup <NUM> is supported by the first lead <NUM> and the conducting wire <NUM> is used to electrically connect the LED chip <NUM> with the second lead <NUM>.

Another structure is a surface mounted device (SMD) type light emitting diode <NUM>, e.g. as illustrated in <FIG>. This SMD is a "side-emitting type" and has a light-emitting window <NUM> on a protruding portion of a light guiding member <NUM> and is particularly useful for backlight applications. An SMD package may comprise an LED chip as defined above, and a phosphor material that is excited by the light emitted from the LED chip.

When used with an LED emitting light from <NUM> to <NUM> and one or more other appropriate phosphors, the resulting lighting system will produce a light having a white color.

In another embodiment, <FIG> illustrates a backlight unit or module <NUM> according to the present invention that includes light source <NUM>, light guide panel <NUM>, remote phosphor part in the form of a sheet or film <NUM>, filter <NUM>, and LCD panel <NUM>. Backlight unit <NUM> may also optionally include a prism <NUM> and a brightness enhancing film <NUM>. The light source <NUM> is a blue emitting LED. To produce even lighting, blue light from the light source <NUM> first passes through light guide panel <NUM> which diffuses the blue light. The LCD panel <NUM> also includes color filters arranged in subpixels, a front polarizer, a rear polarizer, and liquid crystal as well as electrodes. Generally, there is an air space between the LCD panel <NUM> and the brightness enhancing film <NUM>. The brightness enhancing film <NUM> is a reflective polarizer film which increases efficiency by repeatedly reflecting any unpolarized light back, which would otherwise be absorbed by the LCD's rear polarizer. The brightness enhancing film <NUM> is placed behind the liquid crystal display panel <NUM> without any other film in-between. The brightness enhancing film <NUM> may be mounted with its transmission axis substantially parallel to the transmission axis of the rear polarizer. The brightness enhancing film <NUM> helps recycle the white light <NUM> that would normally be absorbed by the rear polarizer (not shown) of the liquid crystal panel <NUM>, and thus increases the brightness of the liquid crystal display panel <NUM>.

Remote phosphor part <NUM> includes particles 608A of a complex fluoride phosphor of formula I and particles 608B of a second light-emitting material dispersed in a polymer resin. It is "remote" in the sense that the primary light source and the phosphor material are separate elements, and the phosphor material is not integrated with the primary light source as a single element. Primary light is emitted from the primary light source and is travels through one or more external media to radiationally couple the LED light source to the phosphor material. It will be appreciated by those skilled in the art that a backlight unit according to the present invention may vary in configuration. For example, a direct lit configuration may be used. The prism <NUM> may also be removed or substituted by other brightness enhancement component in an alternative embodiment. The brightness enhancing film <NUM> may be removed if desired.

In another embodiment, <FIG> shows a backlight unit <NUM> that includes backplane <NUM>, light guide panel <NUM>, LED light source <NUM>, mounting bracket <NUM>, and a remote phosphor package in the form of a strip <NUM>, mounted in the backplane <NUM>. The remote phosphor part <NUM> is mounted via mounting bracket <NUM> between light guide panel <NUM> and LED light source <NUM>, whereby light emitting from the backlight source <NUM> is transmitted through part <NUM> and then enters the light guide plate <NUM>. The backlight unit may further include a bottom reflector plate arranged between light guide panel <NUM> and the backplane <NUM> and an optical film assembly arranged above the light guide plate <NUM>.

The LED radiationally coupled with the stabilized Mn<NUM>+ doped phosphor may form part of a display device. The display device may include the Mn<NUM>+ doped phosphor radiationally coupled to a light emitting diode, including a mini light emitting diode or a micro light emitting diode which emits light in the blue spectrum. A micro light emitting diode (also known as a micro LED, micro LED, micro-LED, mLED, and pLED), is a technology utilized in displays in which there may be at least one small LED device for each pixel on a screen, or there may be at least more than one small LED device per pixel, and those LED devices may be coupled to red and green phosphors, respectively. Such a display device may include a backlighting unit and a) the stabilized Mn<NUM>+ doped phosphor being part of the back lighting unit of the display device and being in direct or indirect contact with the LED or micro LED, or b) the stabilized Mn<NUM>+ doped phosphor being part of the back lighting unit and being remotely coupled to the LED or micro LED, and optionally being in the form of a film. The stabilized Mn<NUM>+ doped phosphor may be operably connected to the back lighting unit through at least one filter, and the back lighting unit contains the light emitting diode or the micro light emitting diode. In the display device, the Mn<NUM>+ doped phosphor may be operably connected to or part of a back lighting unit of the display device in any way that is known in the art.

In some embodiments, the Mn<NUM>+ doped phosphors according to the present invention are used in direct emission display devices that include arrays of microLEDs having dimensions on the scale of <NUM> to <NUM> mhi or, more specifically, i to <NUM> mhi, and even the scale of <NUM> to <NUM> p , <NUM> to <NUM> pm, or <NUM> to <NUM> pm. Exemplary methods for fabricating direct emission display devices that include phosphor particles in a wavelength conversion layer coupled to the microLEDs are described in <CIT>, and <CIT>. Devices that include a backlight unit or direct emission display according to the present invention include, but are not limited to, TVs, computers, smartphones, tablet computers and other handheld devices that have a display including a semiconductor light source; and a Mn<NUM>+ doped phosphor according to the present invention. In an embodiment, the phosphor particles of the present invention are a part of a device which comprises an LED, quantum dots, a mini LED, or a micro LED. A mini LED is an LED of a size between <NUM> pm and <NUM> pm. The display device according to the present invention may be a television, a computer monitor, a cellular or conventional phone, a digital photo frame, a tablet, an automotive display, an e-book reader, an electronic dictionary, a digital camera, an electronic keyboard, or a gaming device, or any other electronic device with a screen.

Devices according to the present invention may include one or more other light emitting materials in addition to a Mn<NUM>+ doped phosphor. When used in a lighting device or apparatus in combination with a blue or near UV LED emitting radiation in the range of about <NUM> to <NUM>, the resultant light emitted by the assembly may be a white light. Other phosphors or quantum dot (QD) materials, such as green, blue, yellow, red, orange, or other color phosphors or QD materials may be used in a blend to customize the color of the resulting light and produce specific spectral power distributions. In other embodiments, the materials may be physically separated in a multilayered structure or may be present in one or more blends in a multilayered structure. In <FIG>, phosphor composition <NUM> may be a single layer blend or a multilayered structure containing one or more phosphors or QD materials in each layer. In microLED direct emission display devices, individual microLEDs may be separately coupled to a Mn<NUM>+ doped phosphor and other phosphors or quantum dot (QD) materials to yield light having desired specifications.

Suitable phosphors for use in devices according to the present invention, along with a Mn<NUM>+ doped phosphor include, but are not limited to:.

U<NUM>+-doped phosphors may also be used; exemplary compositions include Ba<NUM>Al<NUM>P<NUM>O<NUM>: U<NUM>+, Ba<NUM>P<NUM>O: U<NUM>+ BaZn<NUM>(PO<NUM>)<NUM>: U<NUM>+, and BaBPO: U<NUM>+. Other U<NUM>+-doped phosphors are disclosed in <CIT>, <CIT>, and <CIT>.

Quantum dot (QD) materials for use in devices according to the present invention may be a group II -VI compound, a group III-V compound, a group IV-IV compound, a group IV compound, a group I-III-VI<NUM> compound or a combination thereof. Examples of group II-VI compounds include CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe, HgS, HgSe, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, or
combinations thereof. Examples of group ÏP-V compounds include GaN, GaP, GaAs,
AIN, A1P, AlAs, InN, InP, InAs, GaNP, GaNAs, GaP As, A1NP, AlNAs, AlPAs, IriNP, InNAs, InP As, GaAlNP, GaAlNAs, GaAlPAs, GalnNP, GalnNAs, GalnPAs, InAlNP, InAlNAs, InAlPAs, and combinations thereof Examples of group IV compounds include Si, Ge, SiC, and SiGe. Examples of group I-III-VI<NUM> chalcopyrite-type compounds include CuInS?. , CuInSe<NUM>, CuGaS<NUM>, CuGaSe?, AgInS<NUM>, AglnSe?. , AgGaS<NUM>, AgGaSe?. And combinations thereof.

The QD materials may be a core/shell QD, including a core, at least one shell coated on the core, and an outer coating including one or more ligands, preferably organic polymeric ligands. Exemplary materials for preparing core-shell QDs include, but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, Co, Au, BN, BP, BAs, AIN, A1P, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AIN, A1P, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdSeZn, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, MnS, MnSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, Cul, Si<NUM>N<NUM>, Ge<NUM>N<NUM>, A1<NUM><NUM><NUM>, (Al, Ga, In)<NUM>(S, Se, Te)<NUM>, Al<NUM>CO, and appropriate combinations of two or more such materials. Exemplary core-shell QDs include, but are not limited to, CdSe/ZnS, CdSe/CdS, CdSe/CdS/ZnS, CdSeZn/CdS/ZnS, CdSeZn/ZnS, InP/ZnS, PbSe/PbS, PbSe/PbS, CdTe/CdS and CdTe/ZnS.

The QD materials typically include ligands conjugated to, coordinated with, associated with, or attached to their surface. In particular, the QDs may include a coating layer comprising ligands to protect the QDs from environmental conditions including elevated temperatures, high intensity light, external gasses, and moisture. Such coating layer can also help to control aggregation, and allow for dispersion of the QDs in the matrix material.

Phosphor composition for use in display or lighting devices may include one or more phosphors that result in a green spectral power distribution under ultraviolet, violet, or blue excitation. In the context of the present invention, this is referred to as a green phosphor or green phosphor material. The green phosphor may be a single composition or a blend that emits light in a green to yellow-green to yellow range, such as cerium-doped yttrium aluminum garnets, more particularly (Y,Gd,Lu,Tb)<NUM>(Al,Ga)<NUM>O<NUM>:Ce<NUM>+ (YAG). In
some embodiments, an LED package <NUM> has a color temperature less than or equal to <NUM>°K, and the only red phosphor present in phosphor composition <NUM> is the Mn<NUM>+ doped phosphor; in particular, K2SiF6:Mn<NUM>+. The composition may additionally include a green phosphor. The green phosphor may be a Ce<NUM>+-doped garnet or blend of garnets, particularly a Ce<NUM>+-doped yttrium aluminum garnet, and more particularly, YAG. When the red phosphor is K<NUM>SiF<NUM>:Mn<NUM>+, the mass ratio of the red phosphor to the green phosphor material may be less than <NUM>, which may be significantly lower than for red phosphors of similar composition, but having lower levels of the Mn dopant. Other green-emitting that may be used with the Mn<NUM>+ doped phosphors include green-emitting QD materials and b-SiAlON.

The ratio of each of the individual phosphors in a phosphor blend may vary depending on the characteristics of the desired light output. The relative proportions of the individual phosphors in the various embodiment phosphor blends may be adjusted such that when their emissions are blended and employed in an LED lighting device, there is produced visible light of predetermined x and y values on the CIE chromaticity diagram, and a white light is preferably produced. This white light may, for instance, possess an x value in the range of about <NUM> to about <NUM>, and a y value in the range of about <NUM> to about <NUM>. However, the exact identity and amounts of each phosphor in the phosphor composition can be varied according to the needs of the end user. For example, the material can be used for LEDs intended for liquid crystal display (LCD) backlighting. In this application, the LED color point would be appropriately tuned based upon the desired white, red, green, and blue colors after passing through an LCD/color filter combination. The list of potential phosphors for blending given here is not meant to be exhaustive and these Mn<NUM>+-doped phosphors can be blended with various phosphors with different emission to achieve desired spectral power distributions.

Other materials suitable for use in devices according to the present invention include electroluminescent polymers such as polyfluorenes, preferably poly(<NUM>, <NUM>-dioctyl fluorene) and copolymers thereof, such as poly(<NUM>,<NUM>'-dioctylfluorene-co-bis-N,N'-(<NUM>-butylphenyl)diphenylamine) (F8-TFB); poly(vinylcarbazole) and polyphenylenevinylene and their derivatives. In addition, the light emitting layer may include a blue, yellow, orange, green or red phosphorescent dye or metal complex, or a
combination thereof. Materials suitable for use as the phosphorescent dye include, but are not limited to, tris(l-phenylisoquinoline) iridium (III) (red dye), tris(<NUM>-phenylpyridine) iridium (green dye) and Iridium (III) bis(<NUM>-(<NUM>,<NUM>-difluorephenyl)pyridinato-N,C2) (blue dye). Commercially available fluorescent and phosphorescent metal complexes from ADS (American Dyes Source, Inc. ) may also be used. ADS green dyes include ADS060GE, ADS061 GE, ADS063GE, and ADS066GE, ADS078GE, and ADS090GE. ADS blue dyes include ADS064BE, ADS065BE, and ADS070BE. ADS red dyes include ADS067RE, ADS068RE, ADS069RE, ADS075RE, ADS076RE, ADS067RE, and ADS077RE.

The Mn<NUM>+ doped phosphors of the present invention may be used in applications other than those described above. For example, the material may be used as a phosphor in a fluorescent lamp, in a cathode ray tube, in a plasma display device or in an LCD, as explained above. The material may also be used as a scintillator in an electromagnetic calorimeter, in a gamma ray camera, in a computed tomography scanner or in a laser. These uses are merely exemplary and not limiting.

The present invention is also directed to certain inventive phosphor compositions. For example, the present invention may be directed to a phosphor composition comprising phosphor particles and comprising, on surfaces of the phosphor particles, at least one surface composition selected from the group consisting of: <NUM>) a composition containing a phosphorus-containing moiety and a carbon-containing moiety; <NUM>) a composition containing a phosphorus-containing moiety and a metal fluoride; <NUM>) a composition containing a phosphorus-containing moiety and a carbon-containing moiety and a metal fluoride; and <NUM>) a composition comprising the phosphorus-containing moiety free of an alkyl phosphate compound,, wherein the phosphor particles comprise a Mn<NUM>+ doped phosphor of formula I which is Ax [MFy]:Mn<NUM>+, where A is Li, Na, K, Rb, Cs, or a combination thereof;
M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MFy] ion; y is <NUM>, <NUM> or <NUM>.

The surface composition containing a phosphorus-containing moiety may be formed by exposing the phosphor particles to K2HPO4. The surface composition containing a carbon-containing moiety may be formed by exposing the phosphor particles to one or more of polyoxyethylene octyl phenyl ether, potassium oleate, polyoxyethylene-polyoxypropylene block copolymer, polyoxyethylene (<NUM>) sorbitan monolaurate, poly(acrylic acid sodium salt), and potassium sorbate. The surface composition containing a phosphorus-containing moiety free of an alkylphosphate may be formed by exposing the phosphor particles to K2HPO4.

In one such composition, in an embodiment, the metal fluoride comprises magnesium fluoride. In another embodiment, the compound containing phosphorus comprises a phosphate moiety; in the context of the present invention, 'phosphate' means an ion that contains PO4, and includes the phosphate ion, PO4 hydrogen phosphate ion, HPO4<NUM>, and dihydrogen phosphate ion, H<NUM>P(V. In yet another embodiment, the compound containing carbon comprises at least one selected from the group consisting of: ethylenediaminetetraacetic acid, polyoxyethylene octyl phenyl ether, potassium oleate, polyoxyethylene-polyoxypropylene block copolymer, polyoxyethylene (<NUM>) sorbitan monolaurate, poly(acrylic acid sodium salt), potassium sorbate, and derivatives or salts thereof.

The surface composition improves the quantum efficiency of the phosphor particles upon exposure to liquid water or water vapor. In an embodiment, the phosphor particles exhibit A) a quantum efficiency after exposure to liquid water for one hour at room temperature that is <NUM>% to <NUM>% of the quantum efficiency exhibited before water exposure or B) a quantum efficiency loss upon exposure to <NUM>% relative humidity at <NUM> deg C for <NUM> hours that is less than <NUM>%.

An advantage of the present invention is that the phosphor particles are less agglomerated than would otherwise be the case. In an embodiment, a D<NUM> particle size of the phosphor particles before sonication of a solution containing the particles is no greater than <NUM> pm and the D<NUM> particle size of the phosphor particles after sonication is no greater than <NUM> pm. In other words, the phosphor particles are sufficiently not agglomerated that the use of sonication will result in less of a decrease in agglomeration than would occur with particles which are not treated pursuant to the present invention. Phosphor powders containing substantially unagglomerated particles may show improved flowability and dispersibility during LED package fabrication.

A light emitting diode device is a structure which contains a light emitting diode. In an embodiment, a light emitting diode device is radiationally coupled to and/or comprises the phosphor composition according to the present invention. In another embodiment, the light emitting diode device is a mini LED or a micro LED. In yet another embodiment, a light emitting diode device can comprise an LED chip on which the phosphor composition is deposited. The phosphor composition is optionally dispersed in a polymeric resin in a form of a film.

In the Examples mentioned below, the primary particle size was measured using a scanning electron microscope with procedures that are known in the art, and the secondary particle size was measured using a Horiba LA-950V2 Laser Scattering Particle Size Distribution Analyzer, also with procedures which are known in the art. Primary particle size according to the present application is the particle size of each phosphor particle, whether in agglomerated state or not. The secondary particle size according to the present application is the particle size of each discreet particle or unit of particles. For example, if two <NUM> pm phosphor particles are agglomerated with one another, the primary particle size would be <NUM> pm since that is the size of each of the basic phosphor particles. In this scenario, the secondary particle size would be more than <NUM> pm. For example, it may be <NUM> pm due to the agglomeration.

Span is a measure of the width of the particle size distribution curve for a particulate material or powder, and is defined according to equation (<NUM>): <MAT> Wherein.

Quantum efficiency (QE) measurement is known in the art and can be done, for example, with a spectrometer. QE is a measure of blue photons absorbed/red photons emitted from luminescence of the phosphor. If there is <NUM>% QE, this means that every blue photon which is absorbed results in the emission of a red photon. QE is measured relative to a reference sample so in the present application, when QE's are compared, those are the QEs relative to a reference sample. It is not critical which reference sample is utilized since the comparison is of two or more other samples relative to the reference sample so that the other two or more samples can be compared to one another.

This example is directed to a phosphor having chemical formula K<NUM>SiF<NUM>:Mn<NUM>+. This phosphor powder had an average primary particle size of <NUM> pm as determined by scanning electron microscopy. This phosphor was not stabilized as described in the present application nor exposed to a water test.

lg of the phosphor of Example <NUM> was mixed with <NUM> deionized water in a <NUM> plastic bottle. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and washed <NUM> times with a total of <NUM> acetone (i.e., <NUM> of acetone was used to effectuate the <NUM> washes). The powder was dried under vacuum for at least <NUM> hours.

<NUM> of the phosphor of Example <NUM> was mixed with <NUM> of a <NUM> solution of phosphoric acid in a <NUM> plastic bottle. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and washed <NUM> times with a total of <NUM> acetone. The powder was dried under vacuum for at least <NUM> hours. The powder was added to a fresh bottle and mixed with deionized water in a lg:<NUM> ratio of powder to water. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and washed <NUM> times with a total of <NUM> acetone. The powder was dried under vacuum for at least <NUM> hours.

The experiment of Example <NUM> was repeated, replacing <NUM> phosphoric acid with <NUM> phosphoric acid.

The experiment of Example <NUM> was repeated, replacing <NUM> phosphoric acid with <NUM> oxalic acid.

The experiment of Example <NUM> was repeated, replacing <NUM> phosphoric acid with <NUM> potassium hydrogen phosphate, dibasic.

The experiment of Example <NUM> was repeated, replacing <NUM> phosphoric acid with <NUM> potassium hydrogen phosphate, dibasic (pH <NUM>).

Cured films of a <NUM>-part thermally cured polydimethylsiloxane elastomer (such as is sold as Sylgard <NUM>, from Dow Coming) comprising dispersed phosphor particles were prepared at a concentration of <NUM> of phosphor per <NUM> of silicone. The phosphors used were the ones prepared in Examples <NUM>-<NUM>. The quantum efficiencies (QE) of the phosphor particles were measured in these films.

The results of QE measurements on phosphor containing films are summarized in Table <NUM> for Examples <NUM>-<NUM>.

The data in Table <NUM> shows that the robustness of K<NUM>SiF<NUM>:Mn<NUM>+ phosphor is enhanced by a process comprising mixing K<NUM>SiF<NUM>:Mn<NUM>+ with an aqueous solution of several substances, such as K<NUM>HPO<NUM>, followed by powder isolation and drying. Enhanced robustness is shown as a preservation of QE after mixing the treated phosphor powder with water for <NUM> hour, vs the QE of the untreated powder as produced mixed with water for <NUM> hour, relative to the QE of the starting phosphor powder without mixing with water. The QE of Example <NUM> is <NUM>%, which is not treated with water. The QE of Example <NUM> is <NUM>%, which shows that water can have a large detrimental effect on the QE of phosphors. Example <NUM> is not treated in accordance with the present invention. Example <NUM> is treated in accordance with the present invention and exhibits a QE of <NUM>%, which is much higher than a QE of <NUM>%. In the technology for phosphors, even a small percentage change in QE is significant and phosphor manufacturers are routinely looking for ways to add even a few percentage points of QE to their phosphors. Thus, a jump from <NUM>% to <NUM>% is significant and surprising. Of the Examples above, the effect of treating the phosphor
powder with an aqueous solution of K<NUM>HPO<NUM> was most pronounced in maintaining QE, since Examples <NUM> and <NUM> show a QE of <NUM>% and <NUM>%, respectively.

This Example is directed to a phosphor having chemical formula K<NUM>SiF<NUM>:Mn<NUM>+. This phosphor was not stabilized as described in the present application nor exposed to a water test. The K<NUM>SiF<NUM>:Mn<NUM>+ phosphor of Example <NUM> had an average primary particle size of <NUM> pm as determined by scanning electron microscopy. Furthermore, the phosphor of Example <NUM> was not treated with an HF solution of K<NUM>SiF<NUM> after annealing.

The phosphor used in Example <NUM> is the same as in Example <NUM>, and both are treated with an HF solution saturated with K<NUM>SiF<NUM>after annealing. The Examples are duplicates of one another. The fact that they get similar results for QE means that this experiment is repeatable.

A K<NUM>SiF<NUM>:Mn<NUM>+ phosphor was utilized which has a smaller average primary particle size as Examples <NUM> and <NUM>. The phosphor powder of Example <NUM> had an average primary particle size of <NUM> pm as determined by scanning electron microscopy and did not receive stabilizing treatment according to the present invention.

A K<NUM>SiF<NUM>:Mn<NUM>+ phosphor was utilized which has a smaller average particle size than Examples <NUM> and <NUM>. The phosphor of Example <NUM> had an average primary particle size of <NUM> pm as determined by scanning electron microscopy and did not receive stabilizing treatment according to the present invention.

In four separate experiments, lg of each of the phosphor samples from Example <NUM>, Example <NUM>, Example <NUM>, and Example <NUM>, respectively, was mixed with <NUM> deionized water in a <NUM> plastic bottle. The mixtures were shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixtures were filtered on Whatman #<NUM> filter paper and each washed <NUM> times with a total of <NUM> acetone. The powders were dried under vacuum for at least <NUM> hours.

In four separate experiments, <NUM> of each of the phosphor samples from Example <NUM>, Example <NUM>, Example <NUM>, and Example <NUM>, respectively, was mixed with <NUM> of a <NUM> solution of potassium hydrogen phosphate, dibasic (pH <NUM>), in a <NUM> plastic bottle. The mixtures were shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixtures were filtered on Whatman #<NUM> filter paper and each washed <NUM> times with a total of <NUM> acetone. The powders were dried under vacuum for at least <NUM> hours. The powders were then added to a fresh bottle and mixed with deionized water in a lg:<NUM> ratio of powder to deionized water. The mixtures were shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixtures were filtered on Whatman #<NUM> filter paper and each washed <NUM> times with a total of <NUM> acetone. The powders were dried under vacuum for at least <NUM> hours.

<NUM> of the phosphor sample of Example <NUM> was mixed with <NUM> of a <NUM> solution of potassium hydrogen phosphate, dibasic (pH <NUM>), in a <NUM> plastic bottle. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> minutes. The mixture was filtered on Whatman #<NUM> filter paper and then washed <NUM> times with a total of <NUM> acetone. The powder was dried under vacuum for <NUM> hours. The powder was then added to a fresh bottle and mixed with deionized water in a lg:<NUM> ratio of powder to deionized water. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and then washed <NUM> times with a total of <NUM> acetone. The powder was dried under vacuum for at least <NUM> hours.

The experiment of Example <NUM> was repeated except that the aqueous <NUM> K2HPO4 solution mixed with the phosphor of Example <NUM> was rolled for <NUM> minutes instead of <NUM> minutes.

<NUM> of phosphor from Example <NUM> was mixed with <NUM> of a <NUM> solution of potassium hydroxide (pH <NUM>) in a <NUM> plastic bottle. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and then washed <NUM> times with a total of <NUM> acetone. The powder was dried
under vacuum for <NUM> hours. The powder was then added to a fresh bottle and mixed with deionized water in a lg:<NUM> ratio of powder to ionized water. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and then washed <NUM> times with a total of <NUM> acetone. The powder was dried under vacuum for at least <NUM> hours.

The experiment of Example <NUM> was repeated except that the <NUM> solution of KOH was replaced with a more dilute aqueous KOH solution adjusted to pH <NUM>.

The data shown in Table <NUM> confirms that mixing K<NUM>SiF<NUM>:Mn<NUM>+ phosphor powder with water has a significant detrimental effect on the phosphor's QE. Examples <NUM> and <NUM> clearly show that when the phosphor powder is mixed with an aqueous solution of K2HPO4 prior to mixing with pure water, the phosphor powder is rendered surprisingly more robust against degradation upon subsequent exposure to water. Degradation is indicated by a drop in QE, and samples <NUM>-<NUM>, without K2HPO4 exposure, showed much lower QE than Examples <NUM>-<NUM> which were treated with K2HPO4. Moreover, without intending to be bound by any theory, this measure of stability or robustness is durable in the sense that the benefit persists even after isolation of the powder from the aqueous K2HPO4 treatment solution, washing and drying. The data shows that the stabilization of the powder is surprisingly fast since the QE of powder mixed with aqueous K2HPO4 for just <NUM> minutes was essentially the same as when the mixing time was <NUM> hour or even <NUM> minutes. In Examples <NUM>, <NUM> and <NUM>, <NUM> minutes of exposure to aqueous K2HPO4 resulted in a QE that was just as high as the QE after <NUM> minutes exposure. The phosphor powder is substantially stable in the K2HPO4 treatment solution over extended time periods in spite of the fact that the aqueous K2HPO4 is mostly water which is known to degrade phosphors.

Examples <NUM>, <NUM>, <NUM> and <NUM> are untreated with K2HPO4 and include samples of small particle sizes. Examples <NUM> and <NUM> are both treated with K2HPO4 and include samples with small particle sizes. The results for Examples <NUM> and <NUM> show that the stabilization resulting from treatment of the phosphor powder with aqueous K2HPO4 is surprisingly high even when the K<NUM>SiF<NUM>:Mn<NUM>+ powder has a primary particle size of <NUM> pm.

The surprising stabilization afforded upon treatment of the phosphor with aqueous K2HPO4 is not just a pH effect. As shown in Example <NUM>, mixing phosphor powder with an aqueous solution of KOH that was pH-adjusted to match the pH of <NUM> K2HPO4 (see Examples <NUM>-<NUM>) did not result in phosphor stabilization. In fact, the QE of Example <NUM> was just <NUM>%, which is even lower than Example <NUM> (which was acidic with a pH of
<NUM>) which had a QE of <NUM>% and which was not mixed with a stabilization agent. In other words, adjusting the pH with KOH to be basic (Example <NUM>) resulted in a much worse result than adding no stabilization agent (Example <NUM>). A significant QE drop was also observed in Example <NUM> (QE of <NUM>%) when the phosphor powder was mixed with aqueous KOH (pH <NUM>) that matched the concentration of the K<NUM>HPO<NUM> solutions (<NUM>) in Examples <NUM>-<NUM> where the lowest QE was <NUM>%.

In order to reduce the agglomeration of phosphor particles, several treatments were tested. The objective is to reduce agglomeration so that dispersibility in resins is improved, such that if the phosphor powders are dispersed in, say, films of photoresist or hydrophobic acrylates, the phosphors are uniformly distributed. Various combinations of solvents and surfactants were used. Typical solvents ranged from non-polar hydrocarbon solvents such as <NUM>-octadecene (ODE) to moderately polar isonorbomyl acrylate to polar aprotic propylene glycol monomethyl ether acetate (PGMEA). Surfactant/dispersant additives included those that are non-ionic (oleylamine, oleic acid, polyoxyethylene octyl phenyl ether (which may be sold as Triton X-<NUM>)), anionic (potassium oleate) and cationic (polyethylene oxide derivatized fatty ammonium ethosulphate (which may be marketed as Hypermer KD25-LQ-(MV)). Examples <NUM>-<NUM> had secondary particle size d50 measured using light scattering.

Example <NUM> is a control and consisted of <NUM> of K<NUM>SiF<NUM>:Mn<NUM>+powder having a secondary particle size d50 of <NUM>. No solvent or surfactant/dispersant was added. This control was used to determine the values of the second column of Table <NUM> (Ad50 - ODE + roller (mm)).

K<NUM>SiF<NUM>:Mn<NUM>+ powder from the same lot as Example <NUM> and mixing it with <NUM> of ODE which is an organic solvent. Then, the resulting composition was shaken briefly to mix and rolled at <NUM> rpm for <NUM>-<NUM> minutes. The resulting mixture was then vacuum filtered to collect the powder and rinsed with <NUM> x <NUM> of acetone to remove traces of solvent.

Following the acetone wash the powder was dried on the filter for no more than five minutes before being collected and dried in a vacuum desiccator for at least <NUM> hours. The dry powders were then sieved through a <NUM> mesh screen to improve flowability and then stored in a nitrogen purged box/cabinet until they could be analyzed for particle size distribution (PSD) and quantum efficiency (QE). The secondary particle size d50 was then compared with that measured for Example <NUM> and the difference or"delta" was recorded in the second column of Table <NUM>. The Ad50 was -<NUM>. 4pm, so the d50 of Example <NUM> was <NUM>. 4pm less than the d50 of Example <NUM>. Thus, the use of ODE as solvent reduced the secondary particle size of the sample.

Examples <NUM>-<NUM> were made bytaking20 mL of ODE and combining it with <NUM> of a respective surfactant as identified on the first column of Table <NUM>, and then adding <NUM> of K<NUM>SiF<NUM>:Mn<NUM>+ powder from the same lot as Example <NUM>. Then, the resulting composition was shaken briefly to mix and rolled at <NUM> rpm for <NUM>-<NUM> minutes. The resulting mixture was then vacuum filtered to collect the powder and rinsed with <NUM> x <NUM> of acetone to remove traces of solvent. Following the acetone wash the powder was dried on the filter for no more than five minutes before being collected and dried in a vacuum desiccator for at least <NUM> hours. The dry powders were then sieved through a <NUM> mesh screen to improve flowability and then stored in a nitrogen purged box/cabinet until they could be analyzed for secondary particle size and QE. The secondary particle size d50s were then compared with Example <NUM> and the difference for each, or"delta" was recorded at the second column of Table <NUM>.

Example <NUM> is a control and consists of <NUM> of K<NUM>SiF<NUM>:Mn<NUM>+powder having a secondary particle size d50 of <NUM> pm. No solvent or surfactant/dispersant was added. The QE of Example <NUM> was <NUM>%. This control was used to determine the values of the third column of Table <NUM> (Ad50 - PGMEA + roller (pm)).

Example <NUM> has organic solvent and no surfactant, and was made by taking <NUM> of K<NUM>SiFg:Mn<NUM>+ powder from the same lot as Example <NUM> and mixing it with <NUM> of propylene glycol monomethyl ether acetate (PGMEA) which is an organic solvent. Then,
the resulting composition was shaken briefly to mix and rolled at <NUM> rpm for <NUM>-<NUM> minutes. The resulting mixture was then vacuum filtered to collect the powder and rinsed with <NUM> x <NUM> of acetone to remove traces of solvent. Following the acetone wash the powder was dried on the filter for no more than five minutes before being collected and dried in a vacuum desiccator for at least <NUM> hours. The dry powder was then sieved through a <NUM> mesh screen to improve flowability and then stored in a nitrogen purged box/cabinet until it could be analyzed for PSD and QE. The secondary particle size distribution d50 was then compared with Example <NUM> and the difference or"delta"was recorded in Table <NUM>, so Ad50 was -<NUM> pm so the d50 of Example <NUM> was <NUM> pm less than the d50 of Example <NUM>.

Examples <NUM>-<NUM> were made by taking <NUM> of PGMEA and combining it with <NUM> of a particular surfactant as identified at column <NUM> of Table <NUM> and then adding <NUM> of
K<NUM>SiF<NUM>:Mn<NUM>+ powder from the same lot as Example <NUM>. Then, the resulting composition was shaken briefly to mix and rolled at <NUM> rpm for <NUM>-<NUM> minutes. The resulting mixture was then vacuum filtered to collect the powder and rinsed with <NUM> x <NUM> of acetone to remove traces of solvent. Following the acetone wash the powder was dried on the filter for no more than five minutes before being collected and dried in a vacuum desiccator for at least <NUM> hours. The dry powders were then sieved through a <NUM> mesh screen to improve flowability and then stored in a nitrogen purged box/cabinet until they could be analyzed for PSD and QE. The particle size d50 was then compared with Example <NUM> and the differences or"deltas" was recorded in Table <NUM> at column <NUM>.

Example <NUM> is a control and consists of <NUM> of K<NUM>SiF<NUM>:Mn<NUM>+ powder having a secondary particle size d50 of <NUM> pm. No solvent or surfactant/dispersant was added. The QE for this sample was determined to be <NUM>%. Example <NUM> is the control used in conjunction with columns <NUM>-<NUM> of Table <NUM> (Ad50 - PGMEA + ultrasound (pm); Ad50 - acrylate + roller (pm); Ad50 - acrylate + ultrasound (pm), respectively).

Example <NUM> had organic solvent and no surfactant, and was made by taking <NUM> of K<NUM>SiF<NUM>:Mn<NUM>+ powder from the same lot as Example <NUM> and mixing it with <NUM> of isonorbomyl acrylate which is an organic solvent. Then, the resulting composition was shaken briefly to mix and rolled at <NUM> rpm for <NUM>-<NUM> minutes. The resulting mixture was then vacuum filtered to collect the powder and rinsed with <NUM> x <NUM> of acetone to remove traces of solvent. Following the acetone wash the powder was dried on the filter for no more than five minutes before being collected and dried in a vacuum desiccator for at least <NUM> hours. The dry powders were then sieved through a <NUM> mesh screen to improve flowability and then stored in a nitrogen purged box/cabinet until they could be analyzed for secondary PSD and QE. The secondary particle size d50 was then compared with Example <NUM> and the difference or"delta" was recorded at column <NUM> of Table <NUM>, so Ad50 was -<NUM> pm so the d50 of Example <NUM> was <NUM> less than the d50 of Example <NUM>.

Examples <NUM>-<NUM> were made by taking <NUM> of PGMEA (for Examples <NUM>-<NUM>) or <NUM> of isonorbomyl acrylate (Examples <NUM>-<NUM>) and combining each with <NUM> of a surfactant identified at the last three lines of column <NUM> of Table <NUM>. Subsequently, <NUM> of K<NUM>SiF<NUM>:Mn<NUM>+ powder from the same lot as Example <NUM> was added. Then, the resulting composition was shaken briefly to mix and subjected to either an ultrasonic bath treatment for <NUM> minutes (Examples <NUM>-<NUM> and <NUM>) or rolled at <NUM> rpm for <NUM>-<NUM> minutes (Examples <NUM>-<NUM>). The resulting mixtures were then vacuum filtered to collect the powder and rinsed with <NUM> x <NUM> of acetone to remove traces of solvent. Following the acetone wash the powder was dried on the filter for no more than five minutes before being collected and dried in a vacuum desiccator for at least <NUM> hours. The dry powders were then sieved through a <NUM> mesh screen to improve flowability and then stored in a nitrogen purged box/cabinet until they could be analyzed for secondary PSD and QE. The secondary particle size d50 was then compared with Example <NUM> and the difference or"delta" was recorded in Table <NUM>. Examples <NUM>-<NUM> are recorded at column <NUM> (Ad50 - PGMEA + ultrasound (pm)), Examples <NUM>-<NUM> are recorded at column <NUM> (Ad50 - acrylate + roller (pm)), and Example <NUM> is recorded at column <NUM> (Ad50 - acrylate + ultrasound (pm)) of Table <NUM>. The absolute secondary particle size d50 (i.e., not relative to Example <NUM>) of sample <NUM> is <NUM> pm and the QE was <NUM>%. The absolute secondary particle size d50 (i.e., not relative to Example <NUM>) of sample <NUM> was <NUM> pm and the QE is <NUM>%. The absolute secondary particle size d50 (i.e., not relative to Example <NUM>) d50 of sample <NUM> was <NUM> pm and the QE was <NUM> %.

As can be seen in Table <NUM>, the use of certain solvents can help reduce agglomeration. The use of certain surfactants can also reduce agglomeration. Certain combinations of solvents and surfactants exhibit advantages as well. Regardless of the extent of agglomeration in the initial powder, the potassium oleate, polyoxyethylene octyl phenyl ether, and polyethylene oxide derivatized fatty ammonium ethosulphate (PODFAE) such as may be obtained as Hypermer KD25-LQ-(MV), as the leading anionic, non-ionic, and cationic additive candidates, respectively, resulted in a secondary particle size with absolute secondary d50 of <NUM> - <NUM> pm (i.e., not relative to another sample). The comparison to the controls is shown in Table <NUM>.

Variants of the examples shown above also demonstrate the advantages of the present invention. Examples <NUM>-<NUM> below exemplify this and the results are in Table <NUM>.

This is a control which is K<NUM>SiF<NUM>:Mn<NUM>+ without any surface treatment. In other words, no KEDTA nor K2HPO4, nor potassium oleate, nor PGMEA, nor MgF<NUM> coated phosphor, nor MgSiF<NUM> <NUM><NUM><NUM>, nor H<NUM>SiF<NUM>.

This sample is directed to treatment of K<NUM>SiF<NUM>:Mn<NUM>+ with ethylenediaminetetraacetic acid dipotassium salt dihydrate (KEDTA). A solution was prepared by adding <NUM> K<NUM>HP04, <NUM> KEDTA, <NUM> aqueous <NUM>% H<NUM><NUM><NUM>, and <NUM> distilled H<NUM><NUM> to a <NUM> polypropylene bottle such that the pH was between <NUM>-<NUM>. To that, <NUM> K<NUM>SiF<NUM>:Mn<NUM>+ was added and the bottle was rolled at <NUM> RPM for <NUM> minutes. The material was then allowed to settle, the supernatant decanted and the slurry was vacuum filtered, rinsed once with <NUM> of H<NUM>O + <NUM> <NUM>% H<NUM><NUM><NUM>, and then <NUM> times with <NUM> of acetone before drying under vacuum.

It is also possible to optionally rinse the samples with acetic acid and ethanol, and to dry the samples under vacuum at elevated temperature up to <NUM>. It is also possible to optionally use ultrasonication in place of/in combination with rolling the bottle.

This sample is directed to K<NUM>SiF<NUM>:Mn<NUM>+ treatment with potassium oleate in organic media. Potassium oleate (<NUM>, <NUM> mmol, , <NUM> wt% paste in water from Sigma Aldrich, <NUM> wt% relative to K<NUM>SiF<NUM>:Mn<NUM>+) was dissolved in <NUM> PGMEA. This solution was added to a <NUM> cubic meter plastic bottle containing <NUM> K<NUM>SiF<NUM>:Mn<NUM>+ powder and <NUM> of PGMEA. Three additional <NUM> portions PGMEA were used to rinse the potassium oleate container and added to the <NUM> cubic meter bottle containing the K<NUM>SiF<NUM>:Mn<NUM>+/surfactant mixture (total PGMEA = <NUM>). The <NUM> cubic meter bottle was capped and rolled for <NUM> minutes. The resulting stabilized phosphor powder was transferred to a plastic Buchner funnel and isolated by vacuum filtration. <NUM> of acetone was used to rinse the <NUM> cubic meter plastic bottle and was transferred to the Buchner funnel to wash the solid. Three additional500 mL portions of acetone were used to wash the solid, churning the solid before each wash (total <NUM> acetone), which was then air dried for <NUM> minutes. The slightly wet powder was collected and dried for three days in a vacuum desiccator and then sifted through a <NUM> mesh membrane to afford <NUM> of surfactant treated K<NUM>SiF<NUM>:Mn <NUM>+ product.

This sample is directed to MgF<NUM> coated phosphor. MgSiF<NUM> <NUM><NUM><NUM> (<NUM>, <NUM> mmol) was weighed into a <NUM> plastic jar to which was then added <NUM> of high purity deionized water. After mixing, the slightly cloudy mixture was filtered through a <NUM> pm membrane. The filtered solution was diluted with <NUM> of <NUM>% aq H<NUM>SiF<NUM> (<NUM>, density <NUM>). This made solution A. Separately, <NUM> of K<NUM>SiF<NUM>:Mn<NUM>+ was added to a <NUM> mL plastic beaker containing a large stir bar. Each of two syringe pumps were set up to deliver <NUM> of solution A over <NUM> minutes (<NUM> of solution A total) directly into the reaction mixture. To the beaker containing the phosphor powder was added <NUM> of aq <NUM>% HF saturated with K<NUM>SiF<NUM>. The mixture was stirred vigorously for <NUM> sec (<NUM> rpm) after which the stirring was turned down to <NUM> rpm. The addition of the solution A into the stirring reaction mixture via syringe pump was initiated. After the addition was complete, the stirring was stopped, the stir bar was removed and the reaction mixture was allowed to settle for <NUM> minutes. The supernatant was decanted and discarded. The wet slurry was mixed with <NUM> of <NUM>% aq HF saturated with K<NUM>SiF<NUM> and MgF<NUM>. The wash mixture was allowed to settle for <NUM> minutes and then the supernatant was decanted and discarded. The slurry was transferred to a plastic Buchner funnel fitted with a <NUM> pm fluoropolymer membrane. The residual HF solution was filtered off and the phosphor cake was washed with acetone <NUM> times, using a total of <NUM> acetone, churning the solid before each wash. The product was dried under vacuum for <NUM> days and then sifted through a <NUM> mesh membrane to afford the final product. The results of the testing of Examples <NUM>-<NUM> are shown at Table <NUM>.

The D50 secondary particle size of samples <NUM>-<NUM> were measured as follows:.

The Horiba measurement gives an agglomerated size, which is the size of the agglomerated masses of basic particles. The US measurement gives a minimally agglomerated size, which means that it is the agglomerated masses of basic particles decreased somewhat by the ultrasonication.

The examples <NUM>-<NUM> show that the surface treatments and MgF<NUM> coating surprisingly produce a less agglomerated particle size with little to no drop in quantum efficiency.

Examples <NUM>-<NUM> also show the concomitant maintenance of a good quantum efficiency with a reduction of agglomeration of particles, as explained below.

This is a batch of K<NUM>SiF<NUM>:Mn<NUM>+ which was used in all of Examles <NUM>-<NUM>.

This is the control batch. <NUM> IUSiFyMn<NUM>' from Example <NUM> was put in <NUM> H<NUM><NUM> in a <NUM> Nalgene bottle. It was rolled for <NUM> minutes at <NUM> RPM. The sample was then settled for <NUM> minutes, subjected to a centrifuge pulse to <NUM> RPM (~<NUM> sec), then decanted,
vacuum filtered, washed with acetone <NUM> times, vacuum dried, and sifted through a <NUM> mesh membrane. Example <NUM> does not contain the surface agents of the present invention and is being compared to samples with surface agents.

Examples <NUM>-<NUM> were made as follows: <NUM> K<NUM>SiF<NUM>:Mn<NUM>+from Example <NUM> was put in <NUM> H<NUM><NUM> or <NUM> <NUM> K<NUM>HPO<NUM> (aq) + <NUM> or <NUM> (or <NUM>) of surface agent in a <NUM> Nalgene bottle. The bottle was rolled for <NUM> minutes at <NUM> RPM. The sample was then settled for <NUM> minutes, subjected to a centrifuge pulse to <NUM> RPM (~<NUM> sec), then decanted, vacuum filtered, washed with acetone <NUM> times, vacuum dried, and sifted through <NUM> mesh. The information on the particulars of each Example is found in Table <NUM> below. The ammonium polyacrylate polymer in Examples <NUM> and <NUM> may be sold as Dispex AA <NUM>.

Table <NUM> below shows at column <NUM>, the "Example" number, at column <NUM>, the surfactant or other "Surface Agent" that was used. At column <NUM>, whether or not K<NUM>HPO<NUM> was used (this column is labeled as"<NUM> K<NUM>HPO<NUM>". If that column says Y, then <NUM> of <NUM> of K<NUM>HPO<NUM> was used, if it says N, then just <NUM> of water was used. Column <NUM> may also indicate other additives which are added along with the K<NUM>HPO<NUM> or water, such as adding <NUM> of <NUM>% aqueous solution of H2O2. At column <NUM>, which is labeled as "Amount", lists whether the amount of "Surface Agent" used is <NUM> grams or <NUM>. At column <NUM>, the QE is shown. At column <NUM> is shown AQE, which is the difference in QE between samples that included K<NUM>HPO<NUM> and those that did not.

As shown above at column AQE, the average QE improvement by the use of K2HPO4 was surprisingly <NUM>%. Another observation is that H2O2 increased QE by > <NUM>% as shown for Example <NUM>. Moreover, many of the surface agents also increased QE by a significant amount, as shown in Table <NUM>.

For examples <NUM>-<NUM>, <NUM> of K<NUM>SiF<NUM>:Mn<NUM>+ was added to a solution containing the surface agent listed at Table <NUM> in <NUM> of <NUM> K^FlPO^aq). The surface agent was provided in the amount listed in Table <NUM> as well. The samples were roll milled for <NUM> minutes. The material was then allowed to settle, the supernatant decanted and the slurry was vacuum filtered, rinsed once with <NUM> of H<NUM>O + <NUM> <NUM>% H<NUM>O<NUM>, and then <NUM> times with <NUM> of acetone before drying under vacuum. The dried samples were then sieved through a <NUM> mesh nylon screen. Example <NUM> is the mother batch used for examples <NUM>-<NUM> and was not subject to water treatment. Example <NUM> was subject to water treatment but not to a surface agent. The results of the testing are shown at Table <NUM> with the first column giving the number of the Example, the second column identifying the surface agent used, the third column quantifying the amount of surface agent ("SA") used, and the fourth column providing the QE of such sample. As Table <NUM> demonstrates, the effect of water treatment on Example <NUM> significantly reduced QE. However, the addition of surface agents and K<NUM>HPO<NUM> largely reversed the detrimental QE effects shown at Example <NUM>.

Additional testing results on samples <NUM>-<NUM> are provided at Table <NUM> below.

At table <NUM>, the first column is the Example number. The second column shows the secondary particle sizes as measured without sonication. The third column shows the span with no sonication. Span measures the width of the particle size distribution. In the third column, Examples <NUM> and <NUM>, which were not treated with surface active agents, showed a relatively large span. Except for Example <NUM>, the examples with surface active agents showed a decrease in span relative to Examples <NUM> and <NUM>, which means that they showed better dispersion and less agglomeration since the spread of particle sizes was narrower. In the fourth column is information on secondary particle size with sonication. In the fifth column is information on the span for the samples with sonication. Even with sonication, which improves dispersion and reduces agglomeration, the samples with surface agents decreased the span relative to samples <NUM> and <NUM>, which shows the improvement in dispersion and the decrease in agglomeration. Column <NUM> shows the change in D50 (AD50) between non-sonication and sonication. The AD50 is also related to the degree of dispersion and agglomeration since a greater AD50 means that the sonication had more of an effect on dispersion and agglomeration. Examples <NUM> and <NUM> had greater AD50 than all
of the samples which received surface agent treatment, which means that the examples with the surface treatment improved dispersion and reduced agglomeration.

Example <NUM> contained K<NUM>SiF<NUM>:Mn<NUM>+ without any stabilizing treatment and which was also not exposed to a water test. This is the control used in conjunction with examples <NUM>-<NUM>.

Examples <NUM>-<NUM> were carried out to determine the effect of liquid water exposure of K<NUM>SiF<NUM>:Mn<NUM>+ in the presence of AIPO<NUM>. <NUM> samples of K<NUM>SiF<NUM>:Mn<NUM>+was combined with, respectively, <NUM> of high purity deionized water, <NUM> K<NUM>HPO<NUM>, <NUM> AIPO<NUM>, <NUM> AIPO<NUM> plus <NUM> <NUM>% H<NUM><NUM><NUM>, <NUM> A1PO<NUM>, <NUM> AlPO<NUM> plus <NUM> <NUM>% H<NUM><NUM><NUM>, <NUM> AIPO<NUM>, and <NUM> AIPO<NUM> plus <NUM> of <NUM>% H<NUM><NUM><NUM>. All samples were shaken briefly to mix and rolled at <NUM> rpm for <NUM> hr. The pH of each sample was recorded and then each was filtered and washed three times with acetone (<NUM> total). The filter cakes were collected and dried under vacuum in a desiccator overnight. High purity deionized water was then added to the isolated powders in a lg powder: <NUM> water ratio in a new plastic bottle. These samples were shaken briefly to mix and rolled at <NUM> rpm for <NUM> hr. Each sample was filtered and washed three times with acetone (<NUM> total) and the filter cakes were collected and dried under vacuum in a desiccator overnight.

The results above are consistent with other Examples in which treatment of K<NUM>SiF<NUM>:Mn<NUM>+ with water causes a huge drop in QE and the treatment with K2HPO4 significantly improves the QE. AQE is the difference between the control (Example <NUM>) and the remainder of the Examples (Examples <NUM>-<NUM>). As is clear from the above data, the QE drop with the use of just water (Example <NUM>) was <NUM>%. Surprisingly, all other examples had a much smaller reduction of QE. The largest decrease was <NUM>% which is still much smaller than the QE loss observed for Example <NUM>. This further demonstrates the utility of the present invention in stabilizing phosphors against the detrimental effects of water. While exposure to K2HPO4 resulted in better QE values than AIPO<NUM>, the treatment of both AIPO4 and H2O2 resulted in similar performance as K2HPO4 alone. However, AIPO4 at <NUM> and <NUM> nonetheless resulted in very good QE values even without H2O2.

Examples <NUM>-<NUM> are directed towards the improvement of phosphor robustness towards liquid water and water vapor upon treatment with MgF<NUM> with and without potassium hydrogen phosphate treatment. The starting K<NUM>SiF<NUM>:Mn<NUM>+ phosphor powder had an average secondary d50 particle size of <NUM> pm as determined by light scattering.

lg of the starting K<NUM>SiF<NUM>:Mn<NUM>+ phosphor was mixed with <NUM> deionized water in a <NUM> plastic bottle. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and washed <NUM> times with a total of <NUM> acetone. The powder was dried under vacuum for <NUM> days.

<NUM> of the starting phosphor of Example <NUM> was coated with MgF<NUM> using the amount of MgSiF<NUM> <NUM><NUM><NUM> precursor that produces MgF<NUM> in the amount of <NUM>% by weight with respect to the starting phosphor, according to the procedure defined in Example <NUM>. lg of the coated phosphor was mixed with <NUM> deionized water in a <NUM> plastic bottle. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and washed <NUM> times with a total of <NUM> acetone. The powder was dried under vacuum for <NUM> days.

<NUM> of the starting phosphor of Example <NUM> was coated with MgF<NUM> using the amount of MgSiF<NUM> <NUM><NUM><NUM> precursor that produces MgF<NUM> in the amount of <NUM>% by weight with respect to the starting phosphor, according to the procedure defined in Example <NUM>. After the residual HF solution was filtered off the product and rinsed 2X with acetone, the semi-dry cake was transferred back into the reaction beaker. To this solid was added <NUM> of <NUM> aqueous K2HPO4. The mixture was mixed at <NUM> rpm for <NUM> minutes. The slurry was transferred to a fresh plastic Buchner funnel fitted with a <NUM> pm paper membrane (Whatman GF/F). The aqueous solution was filtered off. The solid was washed with acetone 4X and then dried under vacuum lg of this coated phosphor subsequently treated with K2HPO4 was mixed with <NUM> deionized water in a <NUM> plastic bottle. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and washed <NUM> times with a total of <NUM> acetone. The powder was dried under vacuum for <NUM> days.

<NUM> of the starting phosphor of Example <NUM> was coated with MgF<NUM> using the amount of MgSiF<NUM> <NUM><NUM><NUM> precursor that produces MgF<NUM> in the amount of <NUM>% by weight with respect to the starting phosphor, according to the procedure defined in Example <NUM>. lg of the starting phosphor was mixed with <NUM> deionized water in a <NUM> plastic bottle. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and washed <NUM> times with a total of <NUM> acetone.

The powder was dried under vacuum for <NUM> days.

<NUM> of the starting phosphor of Example <NUM> was coated with MgF<NUM> using the amount of MgSiF<NUM> 6F1<NUM><NUM> precursor that produces MgF<NUM> in the amount of <NUM>% by weight with respect to the starting phosphor, according to the procedure defined in Example <NUM>. After the residual HF solution was filtered off the product and rinsed 2X with acetone, the semi-dry cake was transferred back into the reaction beaker. To this solid was added <NUM> of <NUM> aqueous K<NUM>HPO<NUM>. The mixture was mixed at <NUM> rpm for <NUM> minutes. The slurry was transferred to a fresh plastic Buchner funnel fitted with a <NUM> pm paper membrane (Whatman GF/F). The aqueous solution was filtered off. The solid was washed with acetone 4X and then dried under vacuum lg of this coated phosphor subsequently treated with K<NUM>HPO<NUM> was mixed with <NUM> deionized water in a <NUM> plastic bottle. The mixture was shaken by hand for <NUM> seconds and then rolled at <NUM> rpm for <NUM> hour. The mixture was filtered on Whatman #<NUM> filter paper and washed <NUM> times with a total of <NUM> acetone. The powder was dried under vacuum for <NUM> days.

After mixing the starting phosphor in water for <NUM> hour, the QE dropped from <NUM>% to <NUM>% as shown in Table <NUM> (Example <NUM>). By comparison, the phosphor coated at the <NUM>% MgF<NUM> level dropped down only to <NUM>% (Example <NUM>), and the phosphor coated at the <NUM>% MgF<NUM> level only dropped down to <NUM>% (Example <NUM>). Incorporating treatment of the MgF<NUM>-coated phosphor with aqueous K<NUM>HPO<NUM>, by simply mixing the MgF<NUM>-coated product with <NUM> aqueous K<NUM>HPO<NUM> for <NUM> minutes, resulted in an even more significant preservation of QE upon exposure to liquid water. When phosphor was coated with MgF<NUM> at the <NUM>% level and then mixed with aqueous K<NUM>HPO<NUM>, the QE dropped only <NUM>% upon mixing with pure water for one hour. Also shown by the data in Table <NUM> is the fact that the drop in QE associated with exposure to <NUM>% relative humidity at <NUM> for <NUM> hours was much less with the MgF<NUM>-coated phosphor particles compared to the starting phosphor. The QE drop upon exposure to humidity was reduced even further when the MgF<NUM>-coated phosphor was treated with aqueous K<NUM>HPO<NUM>.

Claim 1:
A process comprising combining a) a solution comprising at least one substance selected from the group consisting of: K<NUM>HPO<NUM>, an aluminum phosphate, oxalic acid, or a combination thereof, with b) a Mn<NUM>+ doped phosphor of formula I in solid form;

        Ax [MFy]:Mn<NUM>+     I

and isolating a stabilized Mn<NUM>+ doped phosphor in solid form; wherein
A is Li, Na, K, Rb, Cs, or a combination thereof;
M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof;
x is the absolute value of the charge of the [MFy] ion;
y is <NUM>, <NUM> or <NUM>, further comprising, prior to combining with at the least one substance, contacting the Mn<NUM>+ doped phosphor of formula I with a fluorine-containing oxidizing agent in gaseous form at an elevated temperature, to form a product phosphor.