Raman spectroscopic analysis of GeS2–Ga2S3–PbI2 chalcohalide glasses

The structures of pseudo-binary GeS2–PbI2, Ga2S3(GaS)–PbI2 and pseudo-ternary GeS2–Ga2S3–PbI2 chalcohalide systems were investigated by Raman scattering spectroscopy. By evolving the vibrational bands as a function of PbI2 content, it was verified that the effect of addition of PbI2 to the glass network is threefold, namely: (i) the conversion of GeS4 tetrahedra to GeS3I and GeS2I2 structural units, (ii) the destruction of ethane-like S3Ga(Ge)–(Ge)GaS3 structural units and formation of GaS3I and GeS3I ones and (iii) formation of short S–S chains and [PbIn] structural units when the concentration of PbI2 is high.