Polymerized Complex Method and CS2 Gas Sulfurization

Rare earth copper sulfides, LnCuS2 (Ln 1⁄4 Ce, Pr, Nd, Sm, Gd and Tb), powders were synthesized by the following procedure: (1) Ln-Cu complex oxide was synthesized using the polymerized complex method, and (2) LnCuO2 was sulfurized by the CS2 gas. CS2 gas sulfurization combined with a polymerized complex method can reduce a reaction temperature and a duration time. TG-DTA and XRD results indicated that Ln0-Cu polymerized complex (Ln 1⁄4 Pr, Nd, Sm and Gd) was decomposed into Ln2O3 (via Ln2OCO3) and Cu/CuO. Ln2O3 reacted with CuO to form Ln2CuO4 complex oxide. In the case of Ce and Tb (Ln 00), a Ln00-Cu polymerized complex was decomposed into LnO2 and Cu/CuO. Ln2CuO4 phase was not observed in these cases. In sulfurization reaction, XRD indicates that Ln CuS2 was formed via a formation of Ln0OCuS. On the other hand, LnCuS2 is considered to be formed via a solid state reaction between Ln 00 2S3 and Cu2S. The contents of oxygen and carbon impurities in the products depend on the sulfurization reaction conditions. For example, the PrCuS2 powder was obtained with low impurity contents of 0.07mass% C and 0.073mass% O by sulfurization at 1223K. [doi:10.2320/matertrans.M2010157]