Interrelations between structural and optical properties of (Cu1��Agx)7GeS5I mixed crystals

Abstract

Cu 1- 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- 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- Ag x ) 7 GeS 5 I are discussed.