PHASE EQUILIBRIUM IN THE Cu2S – Ga2S3 – In2S3 QUASI-TERNARY SYSTEM AND LOW-TEMPERATURE PHOTOLUMINESCENCE IN THE SINGLE CRYSTALS (Ga55In45)2S300 та (Ga54,59In44,66Er0,75)2S300

Abstract

The interaction between the components in the Cu2S - Ga2S3 - In2S3 system has been investigated by methods of direct synthesis, X-ray analysis and differential-thermal analysis. 5 polythermal sections, the isothermal section at 820 K and the liquidus surface projection of the Cu2S – Ga2S3 – In2S3 system have been constructed. The presence of solid solutions based on binary and ternary compounds has been found. The existence of the quaternary phase CuGaxIn5-xS8 has been confirmed, where 1.4 ≤ x ≤ 2.05 at 820 K. The two single crystals (Ga55In45)2S300 and (Ga54,59In44,66Er0,75)2S300 have been grown by solution-melt method. In the (Ga55In45)2S300 single crystal at T = 80 K and the excitation at 488 nm a low PL intensity has been observed, which is associated with defects of the single crystal. The PL band with the maximum at 1540 nm in the (Ga54,59In44,66Er0,75)2S300 single crystal is associated with intracenter transitions in the Er3+ ions.The isothermal section of the Cu2S – Ga2S3 – In2S3 quasi-ternary system at 820 K has been built based on the results of the X-ray analysis. Ternary compounds CuInS2 and CuGaS2 form solid solutions with the structure of chalcopyrite with formula CuGa1-xInxS2, 0 ≤ x ≤ 1, sp. gr. I-42d. There are also γ-solid solutions based on CuGa5S8, sp. gr. I-42m; λ-solid solutions based on GaInS3, sp. gr. P61; μ-solid solutions based on Ga0.7In1.3S3, sp. gr. Cmc21, ι-solid solutions based on CuIn5S8, sp. gr. F-43m in the investigated system. The φ-quaternary phase stretched out along 16.7 mol. % Cu2S. It crystallizes in the hexagonal system and forms equilibrium with β-, λ-, ι-solid solutions.The liquidus surface projection of the system has been built based on the literature and our own research results. On the liquidus surface projection of the system, the areas of primary crystallization of α-solid solutions based on 2-HTM-Cu2S, ε-solid solutions based on 2-HTM-Ga2S3, δ-solid solutions based on 1-HTM-Ga2S3, λ-solid solutions on the basis of GaInS3, ψ-solid solutions based on 2-HTM-In2S3, the φ-quaternary phase and the largest region of the primary crystallization of the β-solid solution based on CuGaS2 exist. Small regions of the primary crystallization of the θ-solid solutions based on 2-HTM-CuInS2 and η-solid solutions based on 1-HTM-CuInS2 also exist. All regions are separated by monovariant curves and non-variant points. μ-Solid solutions based on Ga0,7In1,3S3 and γ-solid solutions based on CuGa5S8 do not have the areas of the primary crystallization on the liquidus surface projection of the system due to the nature of their formation.