Crystallization Kinetics and Phase Transformation of Bismuth Zinc Borate Glass

Abstract

Transparent Bi2ZnOB2O6 glasses were prepared by melt quenching technique. The thermal behavior of the glasses was studied using differential thermal analysis (DTA), structure by X‐ray diffraction (XRD) and the morphology is observed using scanning electron microscope (SEM) and optical polarization microscope. Crystallization kinetics has been studied under isothermal and non‐isothermal conditions by using DTA. Two exothermic peaks were observed in the non‐isothermal DTA curve and XRD analysis confirms that the first exothermic peak belongs to crystallization of β‐BiB3O6 phase whereas the second exothermic peak belongs to formation of Bi2ZnOB2O6 phase. The obtained Avrami parameter indicates that the glass heat‐treated at its first crystallization temperature leads to surface crystallization whereas the glass heat‐treated at second crystallization temperature shows three‐dimensional bulk crystallization. The glasses heated at intermediate temperatures of the exothermic peaks exhibit both the β‐BiB3O6 and Bi2ZnOB2O6 phases indicating the presence of surface and bulk crystallizations. The glass morphological study also confirms the same behavior.