The Preparation of Li1.5Al0.5Ge1.5(PO4)3 Glass-Ceramics with Lithium-Ion Conductivity from an Oxalate Precursor

An Li1.5Al0.5Ge1.5(PO4)(3) glass-ceramic solid electrolyte having a NASICON structure and possessing lithium-ion conductivity is prepared. The differential scanning calorimetry data show that the oxalate precursor significantly reduces the melting temperature of a raw material by 200-300 degrees C to synthesize the Li1.5Al0.5Ge1.5(PO4)(3) glass ceramics. The glass appears to be transparent and colorless after melting at 1150 degrees C and subsequent cooling. The glass transition temperature is 512 degrees C, whereas an intense exothermic crystallization peak of Li1.5Al0.5Ge1.5(PO4)(3) is observed at 633 degrees C. The monophase glass-ceramics, free of nonconductive impurities, is obtained via glass crystallization at 850-900 degrees C. The ionic conductivity of the Li1.5Al0.5Ge1.5(PO4)(3) glass-ceramics is 2 x 10(-4) S/cm at room temperature.