The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 15, 1990
Filed:
Apr. 24, 1989
Ramon L Yale, Towanda, PA (US);
GTE Products Corporation, Stamford, CT (US);
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.