Utilization of DTA in determination of crystallization mechanism in SiO2-Al2O3-CaO-MgO(R2O) glasses in presence of various nuclei

The effect of various nuclei on crystallization mechanism of SiO2-Al2O3-CaO-MgO(R2O) glasses were investigated by differential thermal analysis (DTA) through Matusita, Marotta and modified Kissinger methods. The Avrami constant, n, and the activation energy for crystallization of the most promising specimens containing Cr2O3, Fe2O3 and TiO2 in the single, double and triple nuclei series were determined. According to the results the Avrami constants derived from the Marotta method were more consistent with the other experimental observation. While glasses containing TiO2 as the single nucleant represents surface crystallization and those containing Cr2O3 or Fe2O3 one-dimensional bulk crystallization, the crystallization mechanism of specimens containing both Cr2O3 and Fe2O3 and also the glasses containing the triple nuclei, are bulk and two dimensional.