Crystallization and Physical Properties of LiTaO3in a Reactive Glass Matrix (LiBO2-Ta2O5)

Crystallization kinetics of the glass system (100-x)LiBO2-xTa2O5 (5 ≤ x ≤ 20, in molar ratio) prepared via the conventional metal-plate quenching technique have been studied by the isothermal method using differential thermal analyses (DTA). The X-ray powder diffraction (XRD) of the glasses heat-treated at 790 K/6 h confirmed the evolution of lithium tantalate (LiTaO3) phase in the glass matrix. The value of Avrami exponent n in the Johnson-Mehl-Avrami equation was found to be greater than 3, suggesting a three dimensional growth process with an increasing number of nuclei. Scanning electron microscopy of the heat-treated samples establish the growth of the LiTaO3 crystallites to be spherulitic. These crystallites embedded in the glass matrix were found to be pyro and ferroelectric.