Isothermal section of the Y 2S 3–Cu 2S–GeS 2 system at 870 K and crystal structures of the Y 3Ge 1.25S 7 and Y 3CuGeS 7 compounds

Abstract

The Y 2S 3–Cu 2S–GeS 2 system was investigated using X-ray single crystal and powder diffraction. The existence of the compounds YCuS 2 (YCuS 2 structure type, space group P2 12 12 1) and Y 0.84Cu 1.48S 2–Y 2/3Cu 2S 2 (Er 2/3Cu 2S 2 structure type, space group P 3 ¯ ) was confirmed in the Y 2S 3–Cu 2S section. The formation of the Y 3Ge 1.25S 7 (Dy 3Ge 1.25S 7 structure type, space group P6 3) compound in the Y 2S 3–GeS 2 section was confirmed using X-ray single crystal diffraction ( a = 0.9730(1) nm, c = 0.5826(1) nm, R 1 = 0.0428). The formation of the compounds Cu 8GeS 6 ( β′-Ag 8GeSe 6 structure type, space group Pmn2 1), Cu 4GeS 4 (Cu 4GeS 4 structure type, space group P2 1/ c) and Cu 2GeS 3 (Cu 2SnS 3 structure type, space group Cc) was confirmed in the Cu 2S–GeS 2 section. The isothermal section of the Y 2S 3–Cu 2S–GeS 2 system at 870 K was constructed based on data of the phase analysis of 48 samples. The formation of the new quaternary Y 3CuGeS 7 compound (La 3CuSiS 7 structure type, space group P6 3, a = 0.9835(1) nm, c = 0.5765(1) nm), R 1 = 0.0373) was established in the Y 2S 3–Cu 2S–GeS 2 system.