Crystal structures of the RCuPbS3 (RÂ =Â Tb, Dy, Ho, Er, Tm, Yb and Lu) compounds

The crystal structures of the RCuPbS3 (R = Tb, Dy, Ho, Er, Tm, Yb and Lu) compounds (space group Cmcm, Pearson symbol oC28-4) were determined by means of X-ray single crystal diffraction (a = 0.3925(1) nm, b = 1.2916(4) nm, c = 1.0161(3) nm, R1 = 0.0376 (HoCuPbS3); a = 0.3916(1) nm, b = 1.2934(3) nm, c = 1.0106(2) nm, R1 = 0.0304 (ErCuPbS3); a = 0.3911(1) nm, b = 1.2956(3) nm, c = 1.0064(3) nm, R1 = 0.0441 (YbCuPbS3); a = 0.3899(1) nm, b = 1.2920(4) nm, c = 1.0030(3) nm, R1 = 0.0320 (LuCuPbS3)) and X-ray powder diffraction (a = 0.39413(3) nm, b = 1.2885(1) nm, c = 1.0262(1) nm, RBragg = 0.0907 (TbCuPbS3); a = 0.39297(3) nm, b = 1.2891(1) nm, c = 1.0205(1) nm, RBragg = 0.0851 (DyCuPbS3); a = 0.39096(3) nm, b = 1.29539(9) nm, c = 1.0078(1) nm, RBragg = 0.0943 (TmCuPbS3)). The structure of these compounds is related to the structure of KZrCuS3 and can be described as a packing of R-centered octahedra, Cu-centered tetrahedra and Pb-centered trigonal prisms. The structures of the RCuPbS3 (R = Tb, Dy, Ho, Er, Tm, Yb and Lu) compounds are closely related to the structure of YCuPbS3 (β-BaLaCuSe3 structure type, space group Pnma) where S atoms form similar motifs and the positions of cations are identical.