Process for producing a terbium-activiated gadolinium oxysulfide

Details Process for producing a terbium-activiated gadolinium oxysulfide Process for producing a terbium-activiated gadolinium oxysulfide

1989-04-24

1989-12-19

Cooper, Jack

Compositions

Inorganic luminescent compositions

Zinc or cadmium containing

2523014S, C09K 1184

Patent

active

048881295

ABSTRACT:
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.

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patent: 4690832 (1987-09-01), Yale
"The Influence of ZnO on the Luminescence of LaOBr:Tb.sub.0.0075 ", J. Liu; General Research Institute of Nonferrous Metals, Beijing, China, Y. Wu and F. P. Wang, Dept. of Physics, Beijing University of Iron and Steel Technology, Beijing, China, J. of Lumuin., 40 & 41, 1988, pp. 899-900.

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