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 degrees 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.