Phase Equilibria in the Sn–As–Sb System with Tin Concentrations of Less than 50 mol%

Abstract

Tin- and antimony-based alloys, including SnSb and other compounds of the AIVBV type, are used for the production of anodes for Li+- and Na+ion batteries. Multicomponent solid solutions allow varying the properties of the material and improve the technical characteristics of the anodes. There is very little information in the literature about solid phase solubility in the Sn–As–Sb system, and the phase diagram of the system has not been studied yet. The aim of this paper was to study the polythermal sections SnAs–Sb and SnAs–SnSb using the X-ray diffraction analysis (XRD) and differential thermal analysis (DTA), as well as to construct a phase equilibria scheme for the Sn–As–Sb system with the range of tin concentrations of less than 50 mol%. The alloys of the polythermal sections SnAs–Sb and SnAs–SnSb were obtained from pre-synthesized binary compounds and then subjected to homogenizing annealing. The obtained powdered samples were then investigated using differential thermal analysis (DTA) and X-ray diffraction analysis (XRD). The XRD results showed that all the studied alloys were heterophase mixtures of solid solutions (SnAs), (SnSb) and a¢, where a¢ is a solid solution of tin in the As1–xSbx phase. The concentration range of solid solutions based on binary compounds at room temperature was below 10 mol %. The DTA demonstrated that in several alloys of the two sections the fi rst endothermic effect was observed at the same temperature (393±2oС). This temperature corresponds to the peritectic process involving the above-mentioned phases: L + a¢ ↔ (SnAs) + (SnSb). Using the DTA method and the XRD data, Т–х diagrams of polythermal sections SnAs–Sb and SnAs–SnSb were constructed. The coordinates of the invariant peritectic equilibrium L + a¢ ↔ (SnAs) + (SnSb) were determined; a scheme of phase equilibria in the Sn–As–Sb system with the range of tin concentrations of less than 50 mol % was proposed. To construct a complete scheme of phase equilibria in the ternary system, it is necessary to further investigate the SnAs–Sn4Sb3 and Sn4As3–Sn4Sb3 sections.

Keywords

• sn–as–sb system
• solid solutions
• phase equilibria.