Effect of BaO on the crystallization kinetics of glasses along the Diopside-Ca-Tschermak join

摘要

We report on the effect of BaO on the crystallization kinetics of glasses in the diopside (CaMgSi2O6)-Ca-Tschermak (CaAl2SiO6) system. Partial substitution (i.e. 5%, 10% and 20%) of Ba2+ for Ca2+ was attempted in composition CaMg0.8Al0.4Si1.8O6, in three different glasses while partial substitution of B3+ for Al3+ Was made in the fourth glass, Structural investigations on the glasses have been made by density measurements, molar volume and Infra-red spectroscopy (FTIR). Non-isothermal crystallization kinetic studies have been employed to Study the mechanism or crystallization in all the four glasses. The Avrami parameter for the glass powders is similar to 2, indicating the existence of intermediate mechanism of crystallization. Crystallization sequence in the glasses has been followed by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and FTIR. Augite crystallized out being the dominant phase in all the glass ceramics, while different polymorphs of BaAl(2)Si(2)O8 were present as secondary or minor phases. (C) 2008 Elsevier B.V. All rights reserved.