Structure and properties of GeS2–Ga2S3–CdI2 chalcohalide glasses

Chalcohalide glasses in the GeS2–Ga2S3–CdI2 pseudo-ternary system were prepared by 3–5N pure raw materials. Structures of these glasses were studied with Raman spectroscopy. Several properties, namely, glass transition temperature, optical transmission, density and microhardness have also been measured. Based on the Raman spectra, it can be speculated that the glass network is mainly constituted by [GeS4], [GaS4] tetrahedra with some mixed-anion tetrahedra [S3GeI], [S2GeI2] and [S3GaI], which are interconnected by bridging sulfurs and/or short S–S chains. In the glasses with little CdI2, some part of Ge(Ga) exists in the forms of the ethane-like units [S3(Ga)Ge–Ge(Ga)S3] because of the lack of sulfur, but the amount of these units will decrease with the addition of CdI2. Additionally, in the glasses with high content of CdI2, some [CdIn] structural units (s.u.) will be formed and dispersed homogenously in glass network. These novel glasses have relatively high glass transition temperatures (Tg ranges from 512 to 670 K), good thermal stabilities (the maximum of difference between Tx and Tg is 185 K) and UV–vis optical transmission, large densities (d ranges from 3.162 to 3.863 g/cm3) and microhardness (large than 150 kg/mm2 generally). All properties evolutions follow the structural variations.