Phase transformations of indium mono- and sesquisulfides studied by a novel static thermal analysis technique

Abstract

This paper analyzes some features of the indium-sulfur system studied by differential thermal analysis and a novel, specially developed, static technique: chromatothermography. The technique builds on imaging of the surface of the substance of interest, whose temperature is varied stepwise, with isothermal holds. We describe algorithms for processing such images with the aim of gaining information about phase transition temperatures of the substance. The present results demonstrate that the high-temperature phase of indium monosulfide (InS) exists in a narrow temperature range (≃30 K). The phases In_{3 − x} S₄ (spinel) and In₂S₃ (low-temperature, tetragonal phase), very similar in stoichiometry, are indeed separated by a narrow heterogeneous region. In₂S₃ peritectically decomposes at a temperature near 410°C to form In_{3 − x} S₄ and a sulfur-based melt.