Thermo-optical study of NaPO 3 crystallization

The optical transmittance records taken on the small polished plates of NaPO 3 glass at different linear heating rates, previously kinetically analyzed to derive the activation energy of the glass crystallization applying the Kissinger equation, are presently analyzed according to the modified Johnson-Mehl-Avrami kinetic model. A decrease in the relative transmitted light intensity is taken, as previously, as an inverse measure of the volume fraction of crystallized NaPO 3 . The activation energy of 131±11 kJ mol -1 , derived under these circumstances, is in good agreement with the results published in literature (138 kJ mol -1 ), derived from the isothermal heating-quenching and XRD measurements.