Acta Crystallographica Section B

Structural Science

Volume 55, Part 5 (October 1999)

research papers

Acta Cryst. (1999). B55, 721-725 [ doi:10.1107/S0108768199004541 ]

Structure refinement of Cu₈GeS₆ using X-ray diffraction data from a multiple-twinned crystal

M. Onoda, X.-A. Chen, K. Kato, A. Sato and H. Wada

Abstract: The structure of the orthorhombic room-temperature phase of Cu₈GeS₆ (copper germanium sulfide), M_r = 773.27, has been refined on the basis of X-ray diffraction data from a 12-fold twinned crystal applying a six-dimensional twin refinement technique. For 1804 unique reflections measured using Mo K [alpha] radiation, R_F was 0.083 with 77 structure parameters and 12 scale factors. The symmetry operations, the unit cell and other crystal data are (0, 0, 0; ½, ½, 0) + x, y, z; y, x, z; ¼ - x, ¾ - y, ½ + z; ¾ - y, ¼ - x, ½ + z; a = b = 9.9073 (3) Å, c = 9.8703 (4) Å, [alpha] = [beta] = 90°, [gamma] = 90.642 (4)°; V = 968.7 (1) Å³, Z = 4, D_x = 5.358 Mg m^-3, [mu] = 21.70 mm^-1. The standard setting of the space group and the reduced unit cell are Pmn2₁; a = 7.0445 (3), b = 6.9661 (3), c = 9.8699 (5) Å; Z = 2.

Keywords: X-ray diffraction; Multiple-twinning crystals.