Influence of Al2O3 additions on crystallization mechanism and conductivity of Li2O-Ge2O-P2O5 glass-ceramics

The crystallization mechanism and conductivity of lithium aluminum germanium phosphate LAGP] glass-ceramics fabricated from Li_1+xAl_xGe_2−x(PO₄)₃ (x=0.0-0.7) glass system were investigated as a function of Al₂O₃ additions. A non-isothermal analysis was performed to study the crystallization behavior of LAGP glass-ceramics at various heating rates (5-25K min⁻¹) by the Kissinger equation and the Augis-Bennett equation, illustrating volume crystallization for the glass-ceramics. The crystal identification and microstructure in glass-ceramics containing various Al₂O₃ contents were analyzed by means of XRD and FESEM. The main phase of the glass-ceramics was found to be LiGe₂(PO₄)₃, with AlPO₄ as the impurity phase. Additionally the highest total ionic conductivity (5.8×10⁻⁴ S/cm) at room temperature was obtained when x=0.5 for Li_1+xAl_xGe_2−x(PO₄)₃ (x=0.0-0.7) glass-ceramics, suggesting that it was a promising electrolyte for practical application in all-solid-state lithium batteries.