Gte Products Corporation

Gte Sylvania Incorporated

Osram Sylvania Inc.

Ramon L Yale

James E Mathers

John L Ferri

H David Layman

Nelson W Shearer

A terbium-activated rare earth oxysulfide phosphor with an enhanced blue emission is disclosed. The phosphor includes a rare earth oxysulfide matrix of the nominal formula M.sub.2-x O.sub.2 S:xTb, where M is lanthanum, gadolinium, yttrium, scandium, lutetium, or mixtures of these metals, and x is 0.001-0.2. Copper is incorporated in the matrix to enhance the blue emission of the phosphor. A method of enhancing the blue emission is also disclosed.

Terbium-activated rare earth oxysulfide phosphor with enhanced blue

A fluorine-free, terbium-activated gadolinium oxysulfide phosphor with an enhanced green:blue emission ratio is disclosed. The phosphor includes a gadolinium oxysulfide matrix of the nominal formula Gd.sub.2-x O.sub.2 S:xTb, where x is 0.001-0.2. Silicon from metasilicic acid is incorporated in the matrix to enhance the green:blue emission ratio of the phosphor. A method of enhancing the green:blue ratio is also disclosed.

Terbium-activated gadolinium oxysulfide phosphor with reduced blue

A terbium-activated rare earth oxysulfide phosphor with an enhanced green:blue emission ratio is disclosed. The phosphor includes a rare earth oxysulfide matrix of the nominal formula M.sub.2-x O.sub.2 S:xTb, where M is lanthanum, gadolinium, yttrium, scandium, lutetium or their mixtures, and x is 0.001-0.2. Up to 1000 ppm of dysprosium is incorporated in the matrix to enhance the green:blue emission ratio of the phosphor. A method of enhancing the green:blue ratio is also disclosed.

Terbium-activated rare earth oxysulfide phosphor with enhanced

A process is disclosed for making a rare-earth oxysulfide phosphor resistant to hydrolysis, which comprises forming a slurry of the phosphor in water, adding to the slurry, a zinc compound in an amount sufficient to result in a zinc ion concentration in the water of from about 0.01 molar to about 0.05 molar, separating the resulting zinc-treated phosphor from the liquid portion of the slurry, heating the zinc-treated phosphor in air at a temperature of from about 500.degree. C. to about 600.degree. C. for a sufficient time to enhance the brightness of the phosphor, and screening the resulting heated phosphor to remove non-luminescent material therefrom. The phosphor has a resistance to hydrolysis that is at least about 50% greater than phosphors produced without the zinc treatment.

Process for providing hydrolysis resistant phosphors

A process is disclosed for producing a hydrolysis resistant rare-earth oxysulfide phosphor which comprises forming a uniform mixture of one or more rare earth oxides, sulfur, alkali carbonate, alkali phosphate, terbium oxide, and a zinc compound wherein the zinc compound is provided in an amount sufficient to result in a zinc concentration of from about 0.05% to about 1.0% by weight, heating the mixture in an air atmosphere in a covered vessel at a temperature of from about 900.degree. C. to about 1400.degree. C. for a sufficient time to form a terbium-activated rare-earth oxysulfide, washing the terbium-activated rare-earth oxysulfide with deionized water to remove essentially all of any water soluble impurities which are present, annealing the washed terbium-activated rare-earth oxysulfide in air at a temperature of from about 525.degree. C. to about 590.degree. C. for about 1 hour to about 3 hours to enhance the brightness of the phosphor. The phosphor has a resistance to hydrolysis that is at least about 35% greater than phosphor produced without the zinc addition.

Hydrolysis resistance of rare earth oxysulfide phosphors produced by the

A terbium activated gadolinium oxysulfide phosphor having a green/blue emission ratio of from about 0.7 to about 2.0 is disclosed. A process is disclosed for producing this phosphor which comprises forming a uniform mixture of gadolinium oxide, sulfur, alkali carbonate, alkali phosphate, terbium oxide, wherein the terbium oxide is provided in an amount sufficient to result in a terbium concentration of from about 0.25% to about 0.9% by weight, and a zinc compound wherein the zinc compound is provided in an amount sufficient to result in a zinc concentration of from about 0.05% to about 1.0% by weight, the zinc concentration and the terbium concentration resulting in the above ratio, the ratio increasing as the zinc concentration increases and as the terbium concentration increases, heating the mixture in an atmosphere in a covered vessel at a temperature of from about 900.degree. C. to about 1400.degree. C. for a sufficient time to form terbium-activated gadolinium oxysulfide, washing the terbium-activated gadolinium oxysulfide with deionized water to remove essentially all of any water soluble impurities which are present, annealing the resulting washed terbium-activated gadolinium oxysulfide in air at a temperature of from about 525.degree. C. to about 590.degree. C. for about 1 hour to about 3 hours to enhance the brightness of the phosphor.

Process for producing a terbium-activiated gadolinium oxysulfide x-ray

A process is disclosed for making a rare earth oxysulfide phosphor resistant to hydrolysis. The process involves adding to a water slurry of the phosphor a sufficient amount of a source of silicon dioxide and a water soluble salt which can be an alkaline earth metal salt or a transition group IIB metal salt with agitation for a sufficient time to form a silicate coating on the phosphor with the cation of the water soluble salt becoming the cation of the silicate coating, the amount of the coating being sufficient to impart hydrolysis resistance thereto. The resulting silicate coated phosphor is then separated from the resulting liquor and heated at a sufficient temperature for a sufficient time in ambient atmosphere to remove essentially all of the water therefrom and to produce the final hydrolysis resistant phosphor. A hydrolysis resistant rare earth oxysulfide phosphor is disclosed consisting essentially of a host which can be gadolinium oxysulfide, yttrium oxysulfide, gadolinium-yttrium oxysulfide, and lanthanum oxysulfide, from about 0.001 to about 0.10 moles of terbium per mole of host as an activator, and a sufficient amount of a silicate coating on the phosphor to impart hydrolysis resistance thereto.

Rare earth oxysulfide phosphors and processes for creating the phosphors are disclosed. One process involves wet milling a material comprising a rare earth oxysulfide, removing soluble impurities, drying, forming a relatively uniform admixture comprising the dried material and aluminum oxide with the aluminum oxide content being from about 0.1 to about 1.0 weight percent of the admixture, followed by heating the admixture at a sufficient temperature for a sufficient time to form the phosphor. Another process involves the wet milling, soluble impurity removal and drying steps described above. The dried material is then dry milled without aluminum oxide, and heated as described above. Another process involves the wet milling, soluble impurity removal, drying, dry milling, and heating steps described above except that the material is dry milled with from about 0.1 to about 1.0 weight percent of aluminum oxide.

Rare earth oxysulfide phosphors and processes for creating same

An improved (Gd.sub.1-x Tb.sub.x).sub.2 O.sub.2 S X-ray phosphor, wherein x is from 0.0003 to 0.0045, and persistence causing impurity ions are kept below 5 ppm, exhibits increased brightness in the blue region of the spectrum, while exhibiting acceptably low persistence for X-ray intensifying screen applications.

Terbium-activated gadolinium oxysulfide X-ray phosphor

An X-ray phosphor consists essentially of (Y,Gd).sub.2 O.sub.2 S:Tb where the ratio of yttrium to gadolinium is between about 93/7 and 97/3.

Terbium activated yttrium gadolinium oxysulfide X-ray phosphor and

Y.sub.2 O.sub.3 :Eu red-emitting phosphor exhibits up to about 8 percent brightness increase upon cathode ray excitation and about 3 percent brightness increase upon UV excitation by the addition of about 250 parts per million of Mg(as MgO).

Y.sub.2 O.sub.3 :Eu phosphor having increased brightness

Rare earth activated rare earth fluorogermanates, represented by the formula: [R.sub.1.sbsb.x R.sub.2.sbsb.(1-x) ].sub.a F.sub.b GeO.sub.C wherein x is a value from about 0.9 to about 0.9998, a is a value of from about 2 to about 4, b is from about 0.85 to about 3.15, c is from about 4 to about 7.5 R.sub.1 is selected from the group of Y, Gd and La and R.sub.2 is selected from Eu, Gd, Tb and Pr and R.sub.1 and R.sub.2 are different, are excited by long or short wavelength ultraviolet light. A solid state process for using a blend of the metal oxides and a heat-decomposable fluorine compound is disclosed along with a preferred embodiment wherein the dual rare earth oxide is formed prior to forming the aforementioned blend of metal oxides.

Rare earth activated rare earth fluorogermanate

Europium and ytterbium when added to terbium-activated rare earth phosphors having either a lanthanum oxysulfide, gadolinium oxysulfide, or yttrium oxysulfide host increase the decay period of the phosphors in a controlled manner.

Terbium-activated rare earth oxysulfide phosphors with controlled decay

Terbium-activated rare-earth oxysulfide X-ray phosphors containing small amounts of cerium exhibit shorter decay times than the same materials without cerium. X-ray intensifying screens employing such phosphors enable improved resolution.

Terbium-activated rare earth oxysulfide X-ray phosphors

A process suitable for reclaiming europium-activated yttrium oxysulfide contaminated with europium-activated yttrium oxide and other non-rare earth cathodoluminescent phosphors comprises forming a relatively uniform admixture of specific fluxing agents, the contaminated yttrium oxysulfide phosphor, a sufficient amount of reactive rare earth source selected from reactive yttrium and europium sources to achieve a predetermined yttrium to europium ratio in the admixture and an excess of the theoretical amount of sulfur required to convert the yttrium oxide and the yttrium source to yttrium oxysulfide, heating the admixture at a temperature of at least 850.degree.C in non-oxidizing atmosphere for a time sufficient to convert the yttrium oxide and the yttrium source to a europium-activated yttrium oxysulfide whereby the rare earth materials form a cathodoluminescent material and whereby the non-rare earth materials form water soluble reaction products, washing the resulting material with sufficient water to remove water soluble materials leaving a cathodoluminescent europium-activated yttrium oxysulfide phosphor.

Growing community of inventors

Ulster, PA, United States of America

Ramon L Yale