SPECTROSCOPIC STUDIES OF THE KINETICS OF DEVITRIFICATION OF ND3+-DOPED GLASSES IN THE AKERMANITE GEHLENITE SYSTEM

The kinetics of devitrification of samples with compositions of the akermanite-gehlenite system (Ca2-Al2-2yMgySi1+yO7 (0 less-than-or-equal-to y less-than-or-equal-to 1)) doped with 2% Nd have been studied. It was shown that emission spectra of neodymium in partially devitrified samples can be expressed as superposition of the spectra for glass and crystalline phases of the same chemical composition. This superposition permits the determination of the degree of devitrification. The kinetics of devitrification for those samples were described by the simplest Avrami equation: alpha = 1 - exp(-kt) (alpha is the degree of devitrification, k is a rate constant). The activation energy of the devitrification process corresponds to that found in molten silicates (almost-equal-to 700 kJ/mol).