Crystal structure of ∼RCu3S3 and ∼RCuTe2 (R=Gd–Lu) compounds

The crystal structures of ternary compounds TbCu3S3, Dy1.06Cu2.84S3 (space group R3̄), Ho0.67Cu2S2 (space group P3̄m1), ErCu3S3 (space group P3̄1c), Yb0.80Cu1.60S2, Lu0.67Cu2S2, TbCuTe2, DyCuTe2, Tm1.07Cu0.78Te2, LuCuTe2 (space group P3̄m1), Gd0.75Cu1.74Te2 (space group P3̄1m) were determined by means of X-ray single crystal diffraction. The S(Te) atoms are stacked in a close packed arrangement with the layers in the sequence AB. The R atoms are distributed over octahedral interstices whereas Cu atoms are located in tetrahedral interstices. Disorder of R and Cu atoms in studied chalcogenides is found. Crystal structure comparison showed that TbCuTe2 and DyCuTe2 crystallize as superstructure 2a×2a×2c to CaAl2Si2 structure type, whereas Gd0.75Cu1.74Te2, ErCu3S3 and TbCu3S3 (Dy1.06Cu2.84S3) have superstructure √3a×√3a×nc with n=1, 2, 3.