The study of the quasi-triple system FeS–Ga2S3–Ag2S by a FeGa2S4–AgGaS2 section

Abstract

The interest in the study of systems containing sulphides with the formula AIBIIIСVI 2 is generated in particular by emerging opportunities for their practical use in the production of non-linear optical devices, detectors, solar cells, photodiodes, luminophors, etc. Therefore, taking into account the search for new promising materials based on silver and iron thiogallates, the goal of this work is to study the quasi-binary section FeGa2S4–AgGaS2 of the quaternary system Fe–Ag–Ga–S. The alloys of the AgGaS2-FeGa2S4 system were synthesised from high-purity base metals: iron – 99.995 %, gallium – 99.999 %, silver – 99.99 %, and sulphur – 99.99 %. The alloys were studied using differential thermal analysis, X-ray phase analysis, and microstructural analysis as well as microhardness measurement and density determination. Using the methods of physicochemical analysis, a T-x phase diagram of the AgGaS2-FeGa2S4 section, which is the internal section of the quasi-triple FeS–Ga2S3–Ag2S system, was studied and constructed for the fi rst time. It was established that this system is of the simple eutectic type. The composition of the eutectic point is 56 mol% FeGa2S4 and Т =1100 К. The solid solution ranges were determined on the basis of the source components. Based on FeGa2S4 and AgGaS2 at the eutectic temperature the solubility stretches to 10 and 16 mol% respectively. With decreasing temperature, the solid solutions narrow and, at room temperature, comprise 4 mol% AgGaS2 based on iron thiogallate (FeGa2S4) and 11 mol% FeGa2S4 based on silver thiogallate (AgGaS2).

Keywords

• phase diagram
• solid solution
• fega2s4
• aggas2
• quasi-triple system
• eutectic
• x-ray analysis