Influence of cation substitution on optical constants of (Cu1-xAgx)7SiS5I mixed crystals

Abstract

(Cu1–хAgx)7SiS5I mixed crystals were grown using the vertical zone crystalliza-tion method, they have been shown to crystallize in cubic structure (). The diffuse reflection spectra for the powders of (Cu1–хAgx)7SiS5I mixed crystals were measured at room temperature. Refractive indices and extinction coefficients for (Cu1–хAgx)7SiS5I mixed crystals were obtained from spectral ellipsometry measurements. A nonlinear decrease of the energy pseudogap and a nonlinear behavior with the maximum of refractive index have been revealed with increasing the Ag content. The dispersion of refractive indices of (Cu1–хAgx)7SiS5I has been described in the framework of different models.

Keywords

• mixed crystal
• spectral ellipsometry
• refractive index
• diffuse reflection
• energy pseudogap