Hydrolysis resistance of rare earth oxysulfide phosphors produce

Details Hydrolysis resistance of rare earth oxysulfide phosphors produce Hydrolysis resistance of rare earth oxysulfide phosphors produce

1989-04-24

1990-05-15

Cooper, Jack

Compositions

Inorganic luminescent compositions

Zinc or cadmium containing

2523014S, C09K 1184

Patent

active

049255940

ABSTRACT:
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.

REFERENCES:
patent: 3563909 (1971-02-01), Schuil et al.
patent: 3705858 (1972-12-01), Luckey et al.
patent: 3883747 (1975-05-01), Murashige et al.
patent: 4113648 (1978-09-01), Ferri et al.
patent: 4507560 (1985-03-01), Mathers et al.
patent: 4690832 (1987-09-01), Yale
patent: 4888129 (1989-12-01), Yale

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