Osram Sylvania Inc.

Gte Products Corporation

Global Tungsten & Powders Corp.

Shellie K Northrop

Vaddi B Reddy

Ronald E Karam

Butchi Reddy Vaddi

Xianzhong Chen

Michael J Miller

Chen-Wen Fan

Gregory A Marking

Thomas M Snyder

Chung-nin Chau

Eric F Husted

Chen Wen Fan

Yan Zhang

David T Smith

Thomas Snyder

An electroluminescent phosphor comprising ZnS:Mn is disclosed. Also disclosed are ZnS:Mn electroluminescent phosphors that are free of or substantially free of copper, and/or wherein the phosphor has a D50 size of less than about 5 &#x3bc;m. In addition, a method for preparing a ZnS:Mn phosphor is disclosed, comprising the steps of contacting at least a portion of each of a first solution comprising a Zncompound, a manganese source, and a second solution comprising a Ssource agent; and then heating the mixture at a temperature and for a time sufficient to form a phosphor.

Electroluminescent ZnS:Mn phosphor and method of making

Blue-emitting phosphors for use with plasma display panels (PDP) or other vacuum ultraviolet-excited (VUV) devices are provided. These blue-emitting phosphors and mixtures thereof include at least a europium-activated calcium-substituted barium hexa-aluminate (CBAL) phosphor. Preferably, the CBAL phosphor has a composition which may be represented by the formula: BaCaEuAlO, wherein 0&#x3c;x&#x3c;0.25 and 0.01&#x3c;y&#x3c;0.20. These blue-emitting phosphors exhibit improved degradation characteristics, including reduced color shift and increased intensity maintenance, under conditions found in VUV-excited devices.

VUV-excited device with blue-emitting phosphor

An electroluminescent phosphor powder includes copper-activated zinc sulfide particles that have a size distribution with a D50 value of no more than 10 &#x3bc;m, where no more than 25% of the particles have a size greater than about 15 &#x3bc;m and/or a 24-hr brightness of at least 15 footlamberts. These particles are made by a method that includes first firing copper-doped zinc sulfide mixed with zinc oxide, sulfur and a chloride-containing flux, rapidly cooling the mixture to below 100&#xb0; C., and then mulling and second firing the mixture to provide a powder. The powder can then be elutriated to provide the electroluminescent powder with a narrow particle size distribution (more than 90% between about 5 and 15 &#x3bc;m). The elutriating step can be avoided (albeit with a slightly wider size distribution) by more tightly controlling the first firing temperature.

Method of making electroluminescent phosphors with small particle sizes and powder with D50 value of no more than 10 micrometers

A process for improving the half-life of ZnS:Cu,Cl electroluminescent phosphor wherein the improvement comprises firing a previously first fired material comprised of ZnS:Cu,Cl with a quantity of MgSO .7H O to form a second fired material. The quantity is from 0.015 to 0.15 mole of MgSO .7H O/mole of ZnS.

Preparation of ZnS:Cu,Cl electroluminescent phosphor

An electroluminescent phosphor with an increased efficiency is created by blending a chloride flux, a copper source and a zinc sulfide to form a mixture and then heating the mixture for a period of time, cooling the mixture, and washing it with de-ionized water. The mixture is dried and milled to form cubic ZnS from hexagonal ZnS, forming a beginning uncoated ZnS:Cu,Cl electroluminescent phosphor. This beginning phosphor is added to other materials, including Ga O , forming a second step material (SSM). The SSM is placed into a first vessel, such as a plastic bottle, blended, sifted and then placed in a second inert reaction vessel that is then heated for a period of time. After cooling, the fired SSM is washed with de-ionized water, washed with acetic acid, again washed with de-ionized water to remove residual acid, washed with KCN and again with de-ionized water to remove residual KCN. The fired and washed SSM is then dried, filtered and sifted, producing a new phosphor with an increased efficiency.

Process for producing electroluminescent phosphor with increased efficiency

The brightness of small size terbium activated gadolinium oxysulfide (Gd.sub.2-x Tb.sub.x O.sub.2 S) phosphor is increased by the incorporation of a lithium dopant. The lithium dopant is added to the phosphor by mixing lithium phosphate with the raw materials formulated to make the phosphor.

Lithium doped terbium activated gadolinium oxysulfide phosphor

Electroluminescent phosphors having substantially increased luminance and maintenance over that of prior art electroluminescent phosphors may be made by (1) doping an inorganic intercalation compound having an atomic structure interspersed with vacant spaces, with selected activator ions capable of luminescent emission, and (2) introducing organic monomers or other conductive material into the vacant spaces of the atomic structure of the doped inorganic intercalation compound. The organic monomers may be polymerized in situ to form conductive polymers therein.

Phosphor and method of making same

Method of preparing fluoroplogopite phosphor

A method for reducing impurity levels of calcium, magnesium and/or silicon in hexammine cobalt halide compounds involves the addition of ferric ions and, optionally, soluble fluorides to an aqueous hexammine cobalt (III) chloride solution having a pH of at least 9. Insoluble compounds of magnesium fluoride, calcium fluoride, and/or ferric hydroxide and silicon coprecipitates are removed from the solution by filtration.

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Sayre, PA, United States of America

Shellie K Northrop