Old friends in a new light: 'SnSb' revisited

摘要

The binary pnictide 'SnSb' has been re-investigated using a combination of X-ray, synchrotron and electron diffraction as well as electron microprobe analysis. Its structure was found to be incommensurately modulated with an underlying rhombohedral parent structure of space group symmetry R(3) over barm (No. 166), unit cell parameters a(h) = b(h) = 4.3251(4) angstrom, c(h) = 5.3376(6) angstrom in the hexagonal setting. The incommensurate primary modulation wave vector q(h) = 1.3109(9)c(h)* and the superspace group symmetry is R(3) over barm, (0, 0, similar to 1.311) (No. 166.1). The refinement of the incommensurate structure indicates that the satellite reflections arise from displacive shifts of presumably essentially pure Sn and Sb layers along the hexagonal c-axis, with increasing distance between the Sn-layers and decreasing distance between the Sb layers. (C) 2005 Elsevier Inc. All rights reserved.