Compositional dependence of crystallization behavior in GeS2-Ga2S3-CsI chalcogenide glass

Controllable precipitation of crystals is one of the key points in the fabrication of chalcogenide glass-ceramics. Glass compositions of 65GeS225Ga2S310CsI (GGC25) and 70GeS220Ga2S310CsI (GGC20) are specifically selected, and their glass-ceramic samples are obtained by careful heat treatment. The transmission spectra, grain sizes, and crystal phases of obtained samples are characterized using visible-near IR spectroscopy, SEM, XRD, and Raman scattering. Different crystallization behaviors are evidenced that GeS2 crystals are precipitated in GGC20 glass, and GGC25 samples show two crystallization mechanisms during the heat treatment, that is, Ga2S3 crystals were first precipitated and then the GeS2 ones. The compositional and the microstructural dependences of crystallization behavior are discussed, which would be a significant reference for the controllable crystallization in chalcogenide glasses.