Preparation of lanthanum bismuth oxychloride phosphors

Abstract

Abstract A process is provided for preparing lanthanum bismuth oxychloride phosphors of formula La 1-x-y Bi x RE 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 2 O 3 , Bi 2 O 3 , and a rare earth oxide of formula RE 2 O 3 , together with NH 4 Cl and a flux comprising BaCl 2 , where quantities of NH 4 Cl and BaCl 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° C. to 325° C., followed by (2) from 2 to about 4 hours at about 275° C. to 500° C., and concluded by (3) from about 8 to 10 hours at about 800° C. to 1000° C.; and (c) recovering said phosphor from said mixture by washing the mixture with water.

Inventors

• 👤 Lothar H. Brixner

Bibliographic Details