127I-NQR, 119Sn Mössbauer Effect, and Electrical Conductivity of MSnI3 (M = K, NH4, Rb, Cs, and CH3NH3)

Abstract

In a series of MSnI3 compounds [formula omitted] two types of coordination around the central Sn(II) were found by 127I-NQR and powder X-ray diffraction techniques. They are square pyramidal (for M = NH4, Rb) and octahedral (for M = CH3NH3). CsSnI3, on the other hand, showed a drastic structural change of the anion at 425 K from a square pyramid to a regular octahedron. Associated with this phase transition, the electrical conductivity increased from 4×10−3 S cm−1 to about 102 S cm−1. This metallic modification was characterized by 127I-NQR and 119Sn Mössbauer spectroscopy. © 1990, Verlag der Zeitschrift für Naturforschung. All rights reserved.