Controllable Crystallization of Cesium Halides in GeS2–Sb2S3 Based Chalcogenide Glasses

Abstract The glass-forming ability, crystallization behavior and physical properties of GeS2-Sb2S3-CsX (X = Cl, Br, I) glasses and glass-ceramics (GCs) are systematically studied by various characterization techniques. With the introduction of cesium halides, transparent chalcogenide GCs containing the single nanocrystals of CsX can be obtained in a controlled fashion. The crystallization behavior was investigated in the line of (100-x) (0.5GeS2-0.5Sb2S3)-xCsX glasses. IR-transmitting chalcogenide GCs embedded with CsCl and CsBr nanocrystals of a large crystallinity have been fabricated successfully after thermal treatments, whereas surface crystallization of CsI is dominated in GeS2-Sb2S3–CsI glassy samples. Such distinct crystallization behaviors of CsX crystal phases are compared and discussed with microstructural results. We propose that the ionic diffusion ability of halogen in the GeS2-Sb2S3-CsX glassy network determines the nucleation and crystal growth of CsX. This finding is of guidance meaning for future design of chalcogenide GCs with novel optical functions and microstructures.