Résumé
High and low temperature forms of In16Sn4S32 differ in color (black and orange-red, respectively) and lithium insertion properties. We have studied both forms by X-ray and neutron diffraction techniques and 119Sn Mössbauer spectroscopy. While diffraction techniques show no structural difference, Mössbauer spectra allow to differentiate both phases, as a consequence of the presence of SnI1 in the high-temperature form. We show from tight-binding calculations that both the differences in color and the tin oxidation states are related to the existence of sulfur vacancies in the local environment of the tin atoms. © 2001 Éditions scientifiques et médicales Elsevier SAS.