Ce 和 Th 能削弱新的稀土磷光体的发光。要从这些物料的混合物中分离 Ce 和 Th,在酸溶液(PH 为2.5—3.5)中,加足够的 H_2O_2或其它的氧化剂,以氧化 Ce 和 Th。然后加 KIO_3(稍微过量),以转化所有的 Ce 和 Th,成不溶的碘酸盐,提高 PH,以沉淀Ce 和 Th,留下其它稀土在溶液中。制造磷光体,需要 Gd、Eu、尤其是 Y,成为钒酸 Ce and Th can weaken the luminescence of new rare earth phosphors. To separate Ce and Th from the mixture of these materials, add enough H 2 O 2 or other oxidant to the acid solution (pH 2.5-3.5) to oxidize Ce and Th. Then add KIO_3 (a slight excess) to convert all Ce and Th into insoluble iodate, raise the pH to precipitate Ce and Th, leaving the other rare earths in solution. To make a phosphor, Gd, Eu, especially Y, is needed to be vanadic acid