The crystal structures of R3CuGeS7 (RÂ =Â Ce-Nd, Sm, Gd-Dy and Er)

Crystal structures of R3CuGeS7 (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy and Er) (La3CuSiS7 structure type, space group P63, Pearson symbol hP24) were determined by means of X-ray single crystal diffraction (a = 1.0225(1) nm, c = 0.58350(7) nm, R1 = 0.0213 for Ce3CuGeS7; a = 1.0168(1) nm, c = 0.58223(7) nm, R1 = 0.0284 for Pr3CuGeS7; a = 1.0123(1) nm, c = 0.57942(7) nm, R1 = 0.0240 for Nd3CuGeS7) and X-ray powder diffraction (a = 1.00144(1) nm, c = 0.57714(1) nm, RBragg = 0.0968 for Sm3CuGeS7; a = 0.99428(1) nm, c = 0.57592(1) nm, RBragg = 0.0863 for Gd3CuGeS7; a = 0.98863(1) nm, c = 0.57535(1) nm, RBragg = 0.0838 for Tb3CuGeS7; a = 0.98371(3) nm, c = 0.57552(3) nm, RBragg = 0.0802 for Dy3CuGeS7; a = 0.97415(1) nm, c = 0.57835(1) nm, RBragg = 0.0709 for Er3CuGeS7). The structures are built up from three-dimensional network of RS8 distorted square antiprisms sharing edges, consolidated by GeS4 tetrahedra and CuS3 triangles sharing edges with the antiprisms.