SPECTROSCOPIC STUDIES OF THE KINETICS OF DEVITRIFICATION OF ND3-DOPEDGLASSES IN THE AKERMANITE GEHLENITE SYSTEM()

The kinetics of devitrification of samples with compositions of the ak ermanite-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 superpositi on permits the determination of the degree of devitrification. The kin etics of devitrification for those samples were described by the simpl est Avrami equation: alpha = 1 - exp(-kt) (alpha is the degree of devi trification, k is a rate constant). The activation energy of the devit rification process corresponds to that found in molten silicates (almo st-equal-to 700 kJ/mol).