The structural role of Ti in a thermally-treated Li2O − B2O3–Al2O3 glass system

Abstract

A 50Li2O·45B2O3·5Al2O3 (LBA, in mol%) glass matrix doped with increasing TiO2 content was synthesized and its physical properties were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), and Raman spectroscopy. The thermograms showed typical vitreous curves with two clear crystallization peaks that are related to major crystalline phases in this glass system and in agreement with XRD results. The higher temperature crystallization peak (TC2) shifted towards the lower temperature peak (TC1) as TiO2 content increased. After specific heat treatments, the XRD measurements revealed the α-LiBO2, γ-LiAlO2 and LiTiO2 crystalline phase formations and the predominance of the first phase. The γ-LiTiO2 phase was particularly responsible for the variation in the second peak crystallization kinetics. In addition, crystal growth phase competition between γ-LiAlO2 and LiTiO2 occurred as TiO2 content increased; however, the main α-LiBO2 phase did not change. Raman spectra showed typical phonon modes associated with crystalline phases observed in XRD and main phases observed in DTA. Phonon modes were also associated with the LiTiO2 crystalline phase that was first observed in the glassy matrix.