| 摘要 |
A rare earth element phosphate (Ln) is described, wherein Ln is either: (1) at least one rare earth element selected from cerium and terbium, or (2) lanthanum in combination with at least one of the above two rare earth elements, and wherein the phosphate has a crystalline structure either of the rhabdophane type with a sodium content of at most 6000 ppm, or of the monazite type with a sodium content of at most 4000 ppm. The phosphate can be obtained by the precipitation of a rare earth element chloride at a constant pH lower than 2, and then calcining and redispersing the same in hot water. A phosphor obtained by calcining the phosphate at at least 1000° C. is also described. |
