Quasi-Ternary System Cu2Se-GeSe2-As2Se3

Direct single-temperature method has been employed to synthesize 137 samples of the Cu2Se-GeSe2-As2Se3 system. The samples have been investigated by x-ray diffraction and differential thermal analysis. The isothermal section at 513 K (240  °C), two phase diagrams GeSe2-As2Se3 and Cu2GeSe3-As2Se3, four vertical sections Cu2GeSe3-CuAsSe2, Cu8GeSe6-CuAsSe2, Cu8GeSe6-As2Se3, A-B (A = 85 mol.% GeSe2-15 mol.% Cu2Se; B = 85 mol.% As2Se3-15 mol.% Cu2Se), and the liquidus surface projection onto the concentration triangle have been constructed. The existence of the ternary compounds Cu2GeSe3, Cu8GeSe6 and CuAsSe2 have been confirmed. The fields of the primary crystallization of phases, character, temperatures and coordinates of nonvariant points have been determined.