Preparation of Calcium Lanthanum Sulfide Powders via Alkoxide Sulfurization

Calcium lanthanum sulfide powders were prepared by reacting methoxides of calcium and lanthanum with H 2 S. Alkoxide mixtures of various La/Ca ratios dispersed in methanol were reacted with H 2 S at 25° to 85°C and the amorphous gels obtained after the removal of methanol were heat‐treated in H 2 S for full sulfurization at various temperatures. Up to 500°C, cubic LaS 2 was the only crystalline phase present. Calcium lanthanum sulfide phase started to form at 550°C. In the temperature range of 650° to 750°C, single‐phase calcium lanthanum sulfide powders were obtained for La/Ca = 2.41 and 2.68.