| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rare earth oxide fluorescent material having a sharp particle size distribution and high luminance and useful for fluorescent lamp, etc., by thermally decomposing a specific rare earth element compound to obtain an intermediate composed of a mixed crystal of rare earth oxides having a specific crystal size, adding a flux to the intermediate and baking the mixture. SOLUTION: The objective compound of formula (Ln1-x Ln'x )2 O3 ((x) is 0.001-0.2) is produced by thermally decomposing compounds consisting of a compound of a rare earth element (Ln) selected from Y, Gd, Sc and Lu and a compound of a rare earth element (Ln') selected from Eu, Tb, Sm, Er, Tm, Dy, Ho, Nd and Pr and easily convertible to oxide by heating (e.g. carbonate or nitrate of a rare earth element) to obtain an intermediate raw material for fluorescent material consisting of a mixed crystal of rare earth oxides (Ln2 O3 .Ln'2 O3 ) having a crystallite diameter of 80-200Ådetermined by powder X-ray diffraction analysis, adding 0.0001-0.1mol of a flux such as barium chloride, strontium chloride or calcium chloride to the intermediate raw material and baking the mixture e.g. at 1250-1500 deg.C.
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