Controllable Formation of the Crystalline Phases in Ge–Ga–S Chalcogenide Glass-Ceramics

We prepared chemically stoichiometric, S-poor and S-rich Ge–Ga–S glasses and annealed them at a temperature that was 20°C higher than its respective glass transition temperature. We aimed at tuning the formation of the different crystals in chalcogenide glass-ceramics. Through systematic characterization of the structure using X-ray diffraction and Raman scattering spectra, we found that, GeS₂ and GeS crystals only can be created in S-rich and S-poor glass-ceramics, respectively, while all GeS, Ga₂S₃, and GeS₂ crystals exist in chemically stoichiometric glass-ceramics. Moreover, we demonstrated the homogeneous distribution of the crystals can be formed in the S-rich glass-ceramics from the surface to the interior via composition designing. The present approach blazes a new path to control the growth of the different crystals in chalcogenide glass-ceramics.