Predicted Binary Compounds of Tin and Sulfur

Three known binary compounds of tin (Sn) and sulfur (S), namely, SnS, SnS2, and Sn2S3, have been extensively studied for potential application in energy generation and conversion applications. Inspired by the existence of many metastable phases of SnS, we explore the chemical space of nine crystalline solids with chemical composition SnxS1–x (x falls between 0.25 and 0.75), predicting that Sn3S is thermodynamically stable in a metallic Pmn21 phase. Due to the layered structure of this phase, Sn3S is a quasi two-dimensional material, characterized by highly anisotropic electronic-related properties. Moreover, the discovered metastable structures of Sn3S2, Sn2S, and Sn5S2 are just about 5 meV/atom above the stability limit, and may potentially be realized. The data set of 369 low-energy structures of nine SnxS1–x crystalline solids reported in this work is a reliable sample of the low-energy sector of the chemical space, and thus being useful for the currently established materials databases, providing a playground for future data-mining works in materials discoveries.