Investigation DSC and XRD on the crystallization kinetics in the phosphate Li₂O–Li₂WO₄–TiO₂–P₂O₅ glassy ionic system

Solid electrolytes-based lithium phosphates have achieved a great evolution due to the safety problem in the lithium-ion battery. This work targets to investigate the prepared glasses within the 20Li₂O–(50 − x)Li₂WO₄–xTiO₂–30P₂O₅ system, with 0 ≤ x ≤ 15 mol%. The bonds constituting the framework of these glasses were studied by Raman spectroscopy. The data analysis of the chemical durability showed that the dissolution rates depend on the composition of each glass. Thermal analysis by using the DSC technique was used to determine the activation energy of crystallization, it is found in the glassy composition (x = 5) that E_c= 184.482 kJ/mol. The determinate Avrami parameter is around 1.7, which allows suggesting the mechanism is surface crystallization. The crystallization process of the prepared glasses is carried out by heating samples at a suggested value of temperature around 550 °C for 4 and 12 h, with heating rate of 10 °C/min. The crystallized phases are identified by XRD. The results of the X-ray diffraction analysis confirm that TiO₂ acts mainly as network forming units. The crystalline phases Li₂WO₄ and Li₄P₂O₇ are formed during the crystallization process. The formation of these crystalline phases into the glasses depends on the time of heating at a fixed crystallization temperature. FTIR spectra of the glass–ceramics show nearly the same IR vibrational modes likewise their parent glasses.