LAUSR

The phase formation in the sections Ag2Se–Cu2SnSe3 and Ag8SnSe6–Cu2SnSe3 of the quasi-ternary system Ag2Se–SnSe2–Cu2Sе was studied for the first time by differential thermal analysis (with thermodynamic calculations), X-ray powder diffraction analysis, and microstructural analysis and also by microhardness and density measurements. No new quaternary compounds were detected. It was determined that both sections are quasi-binary and are of simple eutectic type with limited solubility based on the initial selenides. The coordinates of the eutectic points are (40 mol % Ag2Se, 910 K) and (50 mol % Ag8SnSe6, 780 K). The solubility based on Cu2SnSe3 was 10 mol % Ag2Se in the system Ag2Se–Cu2SnSe3 and 15 mol % Ag8SnSe6 in the system Ag8SnSe6–Cu2SnSe3. Single crystals of the compound Cu2SnSe3 and the solid solutions (Cu2SnSe3)1 – х(Ag8SnSe6)х (х = 0.02–0.15) were grown by the Bridgman–Stockbarger directional crystallization method. It was found that these solutions crystallize in the monoclinic system, and the unit cell parameters increase with increasing Ag8SnSe6 content: а = 6.968–6.985 Å, b = 12.051–12.078 Å, с = 6.945–6.968 Å, β = 109.20°–109.30°, space group Сс, Z = 4, and ρ = 5.75–5.86 g/cm3.