By the methods of DTA, XRD, MSA, as well as by measuring the microhardness and determining the density of the alloys, the CuTe–As₂Te₃ system was studied and a phase diagram was constructed. The system state diagram is of the eutectic type and it is characterized by one chemical compound of Cu₃As₄Te₉ composition. Compounds Cu₃As₄Te₉ melts incongruently at 320⁰C. Solid solutions based on As₂Te₃ reaches 8 mol %, and based on CuTe solid solutions are practically not installed. Cu₃As₄Te₉ and As₂Te₃ form an eutectic composition of 45 mol % As₂Te₃ and temperature 265⁰C. The results of X-ray phase analysis have shown that the Сu₃As₄Te₉ compounds is crystallized in the tetragonal syngony with lattice parameters: a = 13.86,  c = 18.05 Å, Z = 9, ρ_pyk. = 6.96 g/cm³, ρ_rent. = 7.06 g/cm³

doi.org/10.32737/0005-2531-2021-1-67-71