Powder preparation and sintering characteristics of rare-earth sesquisulfide ceramics

Dense ceramics were prepared from rare-earth sesquisulfides, Extremely fine-grained precursor oxides were synthesized by evaporative decomposition of solutions, The sesquisulfides were synthesized by direct reaction of the oxides with flowing H2S in the presence of graphite. These reactive, fine-grained, EDS-derived sulfides could be sintered into ceramic compacts that achieved 92-98% of theoretical density. In comparison, the same processing conditions with 25-50 mu m stock powder produced ceramics with only 70-80% of theoretical density.