Phase equilibria, glass formation and optical properties of glasses in the Ag2S–BIVS2–CV2S3 systems (BIV–Ge, Sn; CV–As, Sb)

Abstract

Phase equilibria of the quasi-ternary systems Ag₂S–B^IVS₂–C^V₂S₃ (B^IV– Ge, Sn; C^V–As, Sb) were investigated using phase analysis based on XRD. Isothermal sections at 500 Kand glass formation regions in the respective systems were determined. The quasi-binary sections GeS₂–As₂S₃ and GeS₂–Sb₂S₃ of the studied systems exhibit glass formation in the entire concentration range. Large glass formation regions were also found at the Ag₂S–GeS₂ (0–55 mol.% Ag₂S) and Ag₂S–As₂S₃ (0–75 mol.% Ag₂S) sections. As the starting compounds As₂S₃, GеS₂ and Sb₂S₃ are in the glassy state, they act as the glass-forming agents in the quasi-ternary systems. Glass formation regions in the tin-containing systems are significantly smaller than the analogous germanium-containing ones which is due to metal nature resulting in the change from tetrahedral to octahedral surrounding. Glassy materials may possess interesting optical properties, therefore optical absorption spectra at 297 K were measured. Bandgap energy E_g of the glasses of the quasi-binary system GeS₂–As₂S₃ was estimated from the data on the spectral distribution of the absorption coefficient at the fundamental absorption edge. It was found that the addition of As₂S₃ to germanium (IV) sulfide results in shifting the absorption edge to higher energies.