CERIUM AND/OR TERBIUM PHOSPHATE OPTIONALLY WITH LANTHANUM, PHOSPHOR RESULTING FROM SAID PHOSPHATE AND METHODS FOR PREPARING SAME

摘要

A rare earth (Ln) phosphate is described, wherein Ln is either: (1) at least one rare earth selected from cerium and terbium, or (2) lanthanum in combination with at least one of the two above-mentioned rare earths, and wherein the phosphate has a crystalline structure of the monazite type with a potassium content of at most 6000 ppm. The phosphate can be obtained by the precipitation of a rare earth chloride at a constant pH lower than 2, by calcination at a temperature of at least 700° C. and by redispersion in hot water. A phosphor obtained by calcination of said phosphate at at least 1000° C. is also described.