Crystallization and Raman spectra of langasite-type phases in glasses of la₃Ga₅GeO₁₄-Ba₃Ga₂Ge ₄O₁₄ system

Crystallization of the langasite-type La₃Ga₅GeO ₁₄-Ba₃Ga₂Ge₄O₁₄ mixed crystals in the stoichiometric corresponding glasses was studied by differential thermal and X-ray diffraction analyses, and by Raman spectroscopy. Although the glasses used in this study were multicomponent systems (BaO-La ₂O₃-Ga₂O₃-GeO₂), the langasite-type phases were singly crystallized in the corresponding glasses. The Raman spectroscopic study revealed the structural similarity on the scale of short-range order between the langasite-type phase and the corresponding glasses. This also strongly suggested the coexistence of Ga and Ge with six-coordination in the gallogermanate glasses.