Synthesis and Sintering of Cerium(III) Sulfide Powders

Cerium(III) sulfide (Ce 2 S 3 ) powder was synthesized via the sulfurization of ceria (CeO 2 ) powder using carbon disulfide gas. Single‐phase α‐Ce 2 S 3 could be formed via sulfurization at 973 K for 28.8 ks. The preparation of α‐Ce 2 S 3 became feasible at low temperature, in comparison to sulfurization using hydrogen sulfide gas. According to the fact that the formation of α‐Ce 2 S 3 was accelerated by the addition of carbon black to the CeO 2 powder, carbothermic reduction was considered to become a dominant reaction, as the temperature increased. To obtain the activation energy for the densification of β‐Ce 2 S 3 powder, which was prepared by vacuum heating α‐Ce 2 S 3 , the data of densification by hot pressing was analyzed by a kinetic equation that was proposed by other researchers. As a result, the sintering behavior could be best explained by a grain‐boundary‐diffusion mechanism that had an apparent activation energy of 382 kJ/mol.