The Cu₂Se–Cu₃AsSe₄–Se system has been studied using differential thermal analysis, X-ray diffraction, and emf measurements on concentration cells using Cu₄RbCl₃I₂ as a solid electrolyte. We have constructed a number of vertical sections through the phase diagram, the room-temperature solid-state phase compatibility diagram, and a projection of the liquidus surface. The primary crystallization fields of the phases present and the types and coordinates of in- and univariant equilibria in the system have been identified. The system has been shown to contain a broad liquid–liquid immiscibility region. Using emf data, we evaluated the standard thermodynamic functions of formation and standard entropy of the Cu3AsSe4 compound.

"Phase Equilibria in the Cu₂Se–Cu₃AsSe₄–Se System and Thermodynamic Properties of Cu₃AsSe₄" L. F. Mashadieva, Z. T. Gasanova, Yu. A. Yusibov, and M. B. Babanly. Inorganic Materials, 2018, Vol. 54, No. 1, pp. 8–16.