Фазові рівноваги у квазіпотрійній системі Cu2Se–In2Se3–CuI

Abstract

The interaction between the components in the Cu2Se–In2Se3–CuI system has been inverstigated by methods of direct synthesis, X-ray analysis and differential-thermal analysis. Four phase diagrams, two polythermal sections, the isothermal section at 770 K and the liquidus surface projection of the Cu2Se – In2Se3 – CuI system have been constructed. The presence of solid solutions based on binary and ternary compounds has been found. The isothermal section of the Cu2Se–In2Se3–CuI quasi-ternary system at 770 K has been built based on the results of the X-ray analysis. At 770 K, the CuI compound crystallizes in sp.gr. F-43m, Cu2Se compound crystallizes in sp.gr. F-43m, In2Se3 compound crystallizes in sp.gp. P61. The existence of ternary compounds CuInSe2, CuIn5Se8, CuIn7Se11, CuIn11Se17, CuIn2Se3I has been established in the system. The existence of the region of homogeneity based on CuIn2Se3I up to 15 mol.% in the system CuI–In2Se3 and up to 15 mol.% in the concentration triangle has been established. Binary and ternary compounds form small areas of homogeneity, except CuInSe2. Homogeneity on the basis of CuInSe2 up to 6 mol% in the Cu2Se - In2Se3 system and up to 10 mol% in the depth of the triangle occupies second place. The liquidus surface projection of the system has been built on the literature data and our own results.The projection consists of the primary crystallization fields of the α-solid solutions based on HTM-Cu2Se, Cu3InSe3, ζ-solid solutions based on HTM-CuInSe2, η-solid solutions based on LTMCuInSe2, ε-solid solutions based on CuI, δ-solid solutions based on HTM-In2Se3, θ-solid solutions based on the CuIn2Se3I, CuIn5Se8, CuIn11Se17 compounds. These fields are separated by 17 monovariant curves and 19 nonvariant points that lie on the corresponding planes of nonvariant fourphase processes and in quasi-binary systems. Some of the compounds were formed by peritectic reactions (CuIn5Se8, CuIn11Se17) or solid phase reactions (CuIn3Se5, CuIn7Se11). These two compounds do not have the areas of primary crystallization on the surface of the liquid surface. Keywords: quasi-ternary system; phase equilibrium; isothermal section; solid solutions; liquidus surface projection.