Investigation DSC and XRD on the Crystallization Kinetics in the Phosphate Li2O−Li2WO4−TiO2−P2O5 Glassy Ionic System

Abstract

This work aims 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 DSC technique was used to determine the activation energy of crystallization, it found in the glass of composition (x= 5) that Ec= 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 550°c for 4 hours and 12 hours. The crystallized phases are identified by XRD. The results of X−ray diffraction analysis confirm that TiO2 acts mainly as network forming units. The crystalline phases Li2WO4 (JCPDS# 01−072−0086) and (JCPDS# 01−087−0409) are formed during the crystallization process. The formation of these crystalline phases into the glasses depends on the time of heating at fixed crystallization temperature. FTIR spectra of the glass–ceramics show nearly the same IR vibrational modes as their parent glasses.