Unveiling Non-isothermal Crystallization of CaO–Al2O3–B2O3–Na2O–Li2O–SiO2 Glass via In Situ X-ray Scattering and Raman Spectroscopy

The crystallization in glasses is a paradoxical phenomenon and scarcely investigated. This work explores the non-isothermal crystallization of a multicomponent alumino-borosilicate glass via in situ high-energy synchrotron X-ray diffraction, atomic pair distribution function, and Raman spectroscopy. Results depict the crystallization sequence as Ca₃Al₂O₆ and CaSiO₄ followed by LiAlO₂ with the final compound formation of Ca₃B₂O₆. These precipitations occur in a narrow temperature range and overlap, resulting in a single exothermic peak in the differential scanning calorimetry thermogram. The concurrent nucleation of Ca₃Al₂O₆ and CaSiO₄ is intermediated by their corresponding hydrates, which have dominantly short-range order. Moreover, the crystallization of LiAlO₂ and Ca₃B₂O₆ is strongly linked with the changes of structural units during the incubation stage in non-isothermal heating. These findings clarify the crystallization of multicomponent glass, which have been inferred from ex situ reports but never evidenced via in situ studies.