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Cu 1-х Ag x ) 7 GeS 5 I mixed crystals grown with a vertical-zone crystallization technique are described by the cubic structure 43 F m . We analyze compositional dependences of their lattice parameter and crystal density. Diffusereflection spectra for the powders of (Cu 1-х Ag x ) 7 GeS 5 I are measured at the room temperature. Refractive indices and extinction coefficients are obtained from spectral ellipsometry measurements. When Ag content increases, we observe a nonlinear decrease in the pseudogap and a nonlinear increase in the refractive index, with a maximum. Interrelations between the structural and optical properties of (Cu 1-х Ag x ) 7 GeS 5 I are discussed.

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Thermal evaporation technique is used to deposite (Ga0,2In0,8)2Se3 thin films. The refractive index and extinction coefficient dispersions are obtained from the spectral ellipsometry measurements. The dispersion of the refractive index is described in the framework of the Wemple–Di Domenico model. The optical transmission spectra of a (Ga0,2In0,8)2Se3 thin film are studied in the temperature range 77–300 K. The temperature behavior of the Urbach absorption edge, as well as the temperature dependences of the energy pseudogap and Urbach energy, are investigated. The influence of different types of disordering on the optical absorption edge of a (Ga0,2In0,8)2Se3 thin film is discussed. Optical parameters of a (Ga0,2In0,8)2Se3 thin film and a single crystal are compared.