PURPOSE: To produce a high purity metallic sulfide having a uniform particle size distribution and excellent in fluorescent efficiency by blending a sulfite or a thiosulfate with sulfur powder and a metallic compd. in a prescribed ratio and heating the resultant mixture at a prescribed temp. for a prescribed time.
CONSTITUTION: A mixture of 1-5 mol sulfite or thiosulfate (e.g. sodium sulfite or sodium thiosulfate), 1-20 mol sulfur powder and 1 mol metallic compd. (e.g. sulfate, halide or oxide of a metal selected from the group consisting of prim. transition metals, alkaline earth metals and rare earth metals) is comminuted and heated at 300-800°C for 2-6 hr to obtain particles of the objective metallic sulfide (e.g. ZnS, CaS, Y2O2S, Gd2O2S) having a relatively uniform particle size distribution of 6-8 μm as a simple compd. in high purity. The fluorescent efficiency of a phosphor obtd. from the metallic sulfide is comparable to that of the conventional phosphor or is higher than that by about 15%.
SAI KEIGEN
BEN SHIYOUKOU
CHIYOU SOEI
KURUMA ZENEI
SAI HAN
YU HEIYOU
