The crystal structures of R3CuGeS7 (R = 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 P6(3), Pearson symbol hP24) were determined by means of X-ray single crystal diffraction (a = 1.0225(1) nm, c = 0.58350(7) nm, R-l = 0.0213 for Ce3CuGeS7; a = 1.0168(1)nm, c = 0.58223(7)nm, R-l =0.0284 for Pr3CuGeS7; a = 1.0123(1)nm, c = 0.57942(7)nm, R-l = 0.0240 for Nd3CuGeS7) and X-ray powder diffraction (a = 1.00144(1)nm, c = 0.57714(1)nm, R-Bragg = 0.0968 for SM3CuGeS7; a = 0.99428(1)nm, c = 0.57592(1)nm, R-Bragg = 0.0863 for Gd3CuGeS7; a = 0.98863(l) nm, c = 0.57535(l) nm, R-Bragg = 0.0838 for Tb3CuGeS7; a = 0.98371(3) nm, c = 0.57552(3) nm, R-Bragg = 0.0802 for DY3CuGeS7; a = 0.97415(l) nm, c = 0.57835(l) nm, R-Bragg = 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. (c) 2006 Elsevier B.V. All rights reserved.