Phase equilibria in the Cu₂Se–SnSe–Sb₂Se₃ quasi-ternary system has been studied by differential thermal analysis and powder X-ray diffraction. Some polythermal sections, isothermal sections at 300 K of the phase diagram and the projection of the liquidus surface are constructed. The regions of primary crystallization of phases, the nature and temperatures of non- and monovariant equilibria have been determined. The phase diagram of the SnSe–CuSbSe₂ quasi-binary section has been refined. It was found that a quaternary compound CuSnSbSe₃ is formed in the system by the peritectic reaction. This compound exists in a narrow range ~(650–723 K) temperatures. In addition, in the studied Cu₂Se–SnSe–Sb₂Se₃ system, limited regions of solid solutions based on the SnSe, Sb₂Se₃, CuSbSe₂ and SnSb₂Se₄ compounds have also been revealed

doi.org/10.32737/0005-2531-2022-1-73-82