Characterization of the physicochemical properties of novel SnS2 with cubic structure and diamond-like Sn sublattice

In this paper, a novel polymorph of SnS2 having a cubic Fd-3m structure was prepared by a mechanochemical route; its lattice structure and thermal, electronic, transport, electrochemical and photoelectrochemical properties were systematically characterized. Structural studies indicated that no phase transition occurred in the -250 to 300 degrees C temperature range, with transition to ordinary trigonal P-3m1 phase followed by a significant sulfur loss at higher temperatures. The refined Sn-S interatomic distance of 2.5884(7) angstrom in the new phase is slightly higher than the one found in other polymorphs, while calculation of the energy gap E-g resulted in similar values (1.9 eV) for Fd-3m and P-3m1 structures. The recorded electrical conductivity has a thermally activated character with lower activation energy E-a = 0.52(1) eV in the 40-160 degrees C range and 0.87(2) eV at temperatures exceeding 160 degrees C. Assuming that in the higher temperature range the conductivity is mainly intrinsic, the calculated E-g = 2E(a) approximate to 1.7 eV matches well the calculated E-g. The synthesized SnS2 exhibits interesting photoelectrochemical properties, as well as good electrochemical characteristics when used as the anode material in lithium cells. In situ structural studies, performed during first discharge of such cells, clarified the nature of reaction of lithium with SnS2, which was found to be complex, proceeding through intercalation-like, two-phase-like and decomposition-like stages. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.