Kinetic Analysis of Crystallization in Li1.3Al0.3Ti1.7(PO4)3 Glass Ceramics

The crystallization mechanisms for Li1.3Al0.3Ti1.7(PO4)(3) (LATP) glass ceramics were studied using thermophysical property characterization techniques. Differential scanning calorimetry (DSC) revealed two separate exothermic events that were ascribed to the initial growth and growth to coherency of a dendritic phase. It was found that the commonly used Johnson-Mehl-Avrami is not a suitable kinetic model for this material. Rather, the Sestak-Berggren (SB) autocatalytic kinetic model was used to analyze the DSC data and the activation energy for initial growth (259 kJ/mol) and coherency (272 kJ/mol) was calculated using isoconversional methods. The calculated parameters for the SB model were used to compare experimental and calculated values for heat flow during the crystallization of LATP and good fits were found for both exothermic events.