Optical characteristics of microcrystalline powders of Ag7+x(P1–xSix)S6 solid solutions

Optical characteristics of microcrystalline powders of solid solutions formed in an Ag7PS6-Ag8SiS6 system were studied. The optical characteristics were determined by the diffuse reflectance spectroscopy. The diffuse reflectance spectra were analyzed using the Kubelka–Munk function and the Tauc method. The latter was used to take into account the energy structure of the studied materials. As a result, pseudo-gap values of the Ag7+x(P1–xSix)S6 solid solutions were estimated. It was found out that heterovalent P +5 → Si+4 cationic substitution within the anionic sublattice leads to a monotonic nonline