THE KINETIC AND MECHANISM OF CRYSTALLIZATION OF MGGEO۳ IN ۶۵GEO۲-۱۵PBO-۱۰MGF۲-۱۰MGO GLASS SYSTEM

In this study, the crystallization behavior of a ۶۵GeO۲-۱۵PbO-۱۰MgF۲-۱۰MgO glass (prepared by the conventional melt quenching technique) has been investigated. The microstructure and crystallization behaviors of this glass were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), non-isothermal differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that a fully glassy phase can successfully be prepared by the conventional melt quenching technique exhibiting one-stage crystallization on heating, i.e., the glassy phase transforms into crystalline MgGeO۳ and Pb۵GeO۷ phases. The activation energy for the crystallization, evaluated from the Kissinger equation, was approximately ۲۰۲±۵ kJ/mole using the peak temperature of the exothermic reaction. The Avrami exponent or reaction order, n, indicates the nucleation rate in this glass to increase with time and the crystallization to be governed by a three-dimensional interface-controlled growth.

Keywords:

Lead-germanate glass , Crystallization , Nucleation , Growth , Kinetic.