Gte Products Corporation

Osram Sylvania Inc.

Kenneth T Reilly

Alan D Douglas

Martin B MacInnis

Richard G Gingerich

Vaddi B Reddy

Robin W Munn

John E Landmesser

Henry E Hoffman

Chen-Wen Fan

Robert P McClintic

Gregory A Marking

James N Christini

Richard G W Gingerich

Dale E Benjamin

John A Powers

Richard E Landry

Richard R Borchardt

Nathaniel E Brese

Christopher S Poss

Andrew G Sigai

A process for making an electroluminescent phosphor having a given emission spectra A, comprises the steps of manufacturing a beginning electroluminescent phosphor having an emission spectra B, different than A. A coating is applied to the phosphor having the emission spectra B to increase the resistance of the phosphor to the deleterious effects of moisture and change the emission spectra of the phosphor to emission spectra A. The application of the coating includes the steps of reacting a coating precursor with a mixture of oxygen and ozone.

Encapsulated long life electroluminescent phosphor

A composition and method are provided for reducing the persistence of yttrium tantalate x-ray phosphors having the monoclinic M' structure. Persistence is reduced by incorporating a tungsten additive into the phosphor. The phosphor preferably contains at least about 4 ppm W. The method for incorporating the tungsten additive consists of adding a tungsten containing compound to the mixture of raw materials formulated to make the phosphor and firing the mixture at a temperature and for a time sufficient to form the phosphor.

Yttrium tantalate x-ray phosphors with reduced persistence

An improved blue-green emitting ZnS:Cu,Cl phosphor is made by doping the phosphor with small amounts of gold and increasing the amount of low intensity milling between firing steps. The improved phosphor has better halflife and brightness characteristics while maintaining its desired emission color.

Improved blue-green emitting ZnS:Cu,Cl electroluminescent phosphor and

A improved ZnS:Cu electroluminescent phosphor having a halflife of at least about 900 hours. The halflife improvement is made by doping the phosphor with minor amounts of gold and substantially increasing the amount of low intensity milling between firing steps. The improved phosphor has a dramatically longer halflife without sacrificing brightness or exhibiting large shifts in emission color.

ZnS:Cu electroluminescent phosphor and method of making same

An electroluminescent phosphor composed of copper activated zinc sulfide having an average particle size less than 23 micrometers and a halflife equal to or greater than the halflife of a second phosphor having a similar composition and an average particle size of at least 25 micrometers.

Small size electroluminescent phosphor

A method of making an unactivated yttrium tantalate x-ray phosphor containing an aluminum additive wherein a high brightness phosphor is obtained without the use of a lithium chloride containing flux. The method includes using a high surface area aluminum oxide as the source of the aluminum additive and a lithium sulfate flux.

Method of making an unactivated yttrium tantalate x-ray phosphor

A coated electroluminescent phosphor which can be copper activated zinc sulfide, copper and manganese activated zinc sulfide or copper activated zinc sulfide-selenide is disclosed having a particle size of from less than about 5 micrometers in diameter to about 80 micrometers in diameter. The coating is from about 100 to about 400 angstroms in thickness, and consists essentially of aluminum oxide and is resistant to moisture and relatively chemically inert.

Coated electroluminescent phosphor

A method for increasing the brightness and halflife of an electroluminescent phosphor by increasing the average particle size of the phosphor to greater than 25 micrometers in diameter.

Method for increasing the brightness and halflife of electroluminescent

A phosphor composition consisting essentially of particles of zinc sulfide electroluminescent phosphor activated with from about 0.7% by weight of about 1.3% by weight of manganese, based upon the total weight of the phosphor composition, wherein the electroluminescent emission of the phosphor has an x color coordinate value of from about 0.522 to about 0.532 and a y color coordinate value of from about 0.460 to about 0.470 and an efficiency of greater than about 5.6 lumens per watt at 115V/400 Hz. A solid state process for producing the foregoing phosphor comprises a multiple firing in order to incorporate manganese, chloride and copper ions into the zinc sulfide lattice. Controlled levels of manganese yield highly efficient electroluminescent phosphors.

Process for producing electroluminescent yellow zinc sulfide phosphors

A process is disclosed for producing tungstosilicic acid which involves adding sodium silicate to a first solution of sodium tungstate while assuring that the pH of the resulting mixture is from about 2 to about 6, the pH adjustments being made with a cation exchange resin on the hydrogen cycle, to produce a second solution. The solids are removed from the second solution which is digested at a temperature of greater than about 50.degree. C. and then contacted with a cation exchange resin on the hydrogen cycle to produce a third solution which is essentially a tungstosilicic acid solution containing at least about 99% by weight of the starting tungsten as tungstosilicic acid.

Process for producing tungstosilicic acid

A process is disclosed for producing an electroluminescent phosphor which comprises blending a chloride flux, a copper source, and zinc sulfide to form a relatively uniform admixture, heating the admixture at a temperature of from about 1000.degree. C. to about 1300.degree. C. for about 2 to about 8 hours to convert at least a portion of the admixture to a crystalline material containing zinc sulfide, at least some chloride ions, and copper ions, washing the material with sufficient water to remove at least a major portion of the water soluble material from the crystalline material, drying the material to produce a relatively moisture-free material which is low intensity milled for a sufficient time to change the crystallographic structure of at least a portion of the moisture-free material, blending the milled material with zinc sulfate and copper sulfate, with or without manganese carbonate depending on whether manganese is desired as an activator, to form a second admixture, which is heated at a temperature of from about 750.degree. C. to about 850.degree. C. for about 1.5 to about 3 hours to form an activated material which is cooled for a period of time of from about 10 minutes to about 20 minutes followed by immediately quenching in water, removing the water from the cooled and quenched activated material, washing the material with reactive aqueous solutions to remove residual fluxes and excess activator materials, and drying the material to form an electroluminescent phosphor.

Process for producing electroluminescent phosphors of improved brightness

In a method for producing tungsten hexachloride which comprises reacting tungsten with chlorine gas at a temperature sufficient to result in the conversion of the tungsten to tungsten hexachloride, the improvement comprising reacting tungsten in the form of pressed pieces to convert the pieces to tungsten hexachloride having an oxygen content of less than about 0.5% by weight with the rate of conversion to tungsten hexachloride being at least about 2.3 times greater than the rate of conversion when the tungsten is in an unpressed form.

Method for producing tungsten hexachloride

A process is disclosed for producing ammonium tetrathiomolybdate. The process involves reacting an ammoniacal molybdate solution with hydrogen sulfide gas, the solution and the gas being in a closed system and the flow of the gas being regulated at an elevated pressure to form a slurry consisting essentially of a solid essentially all of which is ammonium tetrathiomolybdate containing a portion of the starting molybdenum and a mother liquor containing the balance of the molybdenum. The slurry is then cooled to ambient temperature and the solid is removed from the major portion of the mother liquor. The solid is then washed with water and with alcohol followed by removal of the resulting respective water and alcohol washes to remove the remaining portion of the mother liquor and soluble impurities from the solid. The resulting washed solid is then dried at ambient temperature to form the final ammonium tetrathiomolybdate.

Production of ammonium tetrathiomolybdate

A process is disclosed for producing ammonium tetrathiotungstate. The process involves reacting an ammoniacal tungstate solution with hydrogen sulfide gas, the solution and the gas being in a closed system and the flow of the gas being regulated at an elevated pressure to form a slurry consisting essentially of a solid essentially all of which is ammonium tetrathiotungstate containing a portion of the starting tungsten and a mother liquor containing the balance of the tungsten. The slurry is then cooled to ambient temperature and the solid is removed from the major portion of the mother liquor. The solid is then washed with water and with alcohol followed by removal of the resulting respective water and alcohol washes to remove the remaining portion of the mother liquor and soluble impurities from the solid. The resulting washed solid is then dried at ambient temperature to form the final ammonium tetrathiotungstate.

Production of ammonium tetrathiotungstate

A process is disclosed for recovering tungsten and rhenium from a tungsten and rhenium source. The process involves firing the source in an oxidizing atmosphere at a sufficient temperature for a sufficient time to convert the tungsten and rhenium to their respective oxides, to remove a portion of the rhenium as volatilized oxide, and to form a first fired material containing essentially all of the tungsten and the remaining portion of the rhenium, increasing the surface area of the resulting oxidized tungsten, and firing the first fired material in an oxidizing atmosphere at a sufficient temperature for a sufficient time to remove essentially all of the remaining portion of the rhenium as volatilized oxidized rhenium and to form an essentially rhenium-free oxidized tungsten.

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Towanda, PA, United States of America

Kenneth T Reilly