Old friends in a new light: "SnSb" revisited

Abstract

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 R3̄m (No. 166), unit cell parameters ah=bh=4.3251(4)Å, ch=5.3376(6)Å in the hexagonal setting. The incommensurate primary modulation wave vector qh=1.3109(9)ch* and the superspace group symmetry is R3̄m (0, 0, ∼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.