Second-order optical nonlinearity and ionic conductivity of nanocrystalline GeS2–Ga2S3–LiI glass-ceramics with improved thermo-mechanical properties

Abstract

IR-transparent chalcogenide glass-ceramics were fabricated through a careful ceramization process of the as-prepared 65GeS₂·25Ga₂S₃·10LiI glasses at a temperature of 403 °C for various durations. Owing to the precipitation of Li_xGa_yS_z crystals with a Ga₂S₃-like structure, clear second-harmonic generation was observed in the sample crystallized at 403 °C for 60 h, which has a greatly improved resistance to environmental impairment. Additionally, it is found that the shorter crystallization process (≦60 h) contributed to the enhancement of Li⁺ ionic conductivity, whereas a longer heat-treatment (80 h) would impair that of the glass-ceramics. The micro-structural origin of these varied properties was elucidated in detail. The corresponding results will be of benefit for the optimization of designed transparent chalcogenide glass-ceramics with improved thermo-mechanical properties, a permanent second-order optical nonlinearity, or a well-enhanced ionic conductivity for application in amorphous solid electrolytes.