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:
Dec. 18, 1984
Filed:
Apr. 22, 1983
Lothar H Brixner, West Chester, PA (US);
E. I. Du Pont de Nemours and Company, Wilmington, DE (US);
Abstract
A process is provided for preparing lanthanum bismuth oxychloride phosphors of formula La.sub.1-x-y Bi.sub.x RE.sub.y OCl, where RE is a rare earth element, x is 0.001 to about 0.25, and y is 0 to 0.005. The process is characterized by a single firing step, and comprises (a) forming an intimate mixture of stoichiometric quantities of La.sub.2 O.sub.3, Bi.sub.2 O.sub.3, and a rare earth oxide of formula RE.sub.2 O.sub.3, together with NH.sub.4 Cl and a flux comprising BaCl.sub.2, where quantities of NH.sub.4 Cl and BaCl.sub.2, by weight, can be independently chosen from between about one-third to about one-half that of the combined weights of the oxides; (b) firing said mixture, in an inert container and in air, according to a time-temperature sequence in which the mixture is heated (1) from 1 to about 4 hours at about 275.degree. C. to 325.degree. C., followed by (2) from 2 to about 4 hours at about 275.degree. C. to 500.degree. C., and concluded by (3) from about 8 to 10 hours at about 800.degree. C. to 1000.degree. C.; and (c) recovering said phosphor from said mixture by washing the mixture with water.