Unveiling Non-isothermal Crystallization of CaO-Al 2 O 3 -B 2 O 3 -Na 2 O-Li 2 O-SiO 2 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 Ca 3 Al 2 O 6 and CaSiO 4 followed by LiAlO 2 with the final compound formation of Ca 3 B 2 O 6 . 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 Ca 3 Al 2 O 6 and CaSiO 4 is intermediated by their corresponding hydrates, which have dominantly short-range order. Moreover, the crystallization of LiAlO 2 and Ca 3 B 2 O 6 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.