Synthesis of LnCuS<SUB>2</SUB> (Ln=Ce, Pr, Nd, Sm, Gd, and Tb) Powder by Polymerized Complex Method and CS<SUB>2</SUB> Gas Sulfurization

Rare earth copper sulfides, LnCuS 2 (Ln ¼ 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) LnCuO 2 was sulfurized by the CS 2 gas.CS 2 gas sulfurization combined with a polymerized complex method can reduce a reaction temperature and a duration time.TG-DTA and XRD results indicated that Ln 0 -Cu polymerized complex (Ln ¼ Pr, Nd, Sm and Gd) was decomposed into Ln 0 2 O 3 (via Ln 0 2 OCO 3 ) and Cu/CuO.Ln 0 2 O 3 reacted with CuO to form Ln 0 2 CuO 4 complex oxide.In the case of Ce and Tb (Ln 00 ), a Ln 00 -Cu polymerized complex was decomposed into Ln 00 O 2 and Cu/CuO.Ln 002 CuO 4 phase was not observed in these cases.In sulfurization reaction, XRD indicates that Ln 0 CuS 2 was formed via a formation of Ln 0 OCuS.On the other hand, Ln 00 CuS 2 is considered to be formed via a solid state reaction between Ln 00 2 S 3 and Cu 2 S. The contents of oxygen and carbon impurities in the products depend on the sulfurization reaction conditions.For example, the PrCuS 2 powder was obtained with low impurity contents of 0.07 mass% C and 0.073 mass% O by sulfurization at 1223 K.