EVALUATION OF GLASS STABILITY FROM NONISOTHERMAL KINETIC DATA

Non-isothermal devitrification of 1.1Li2O.1.9SiO2 glass has been studied and is compared with that of Li2O.2SiO2 glass reported in the literature. In both cases the devitrification mechanism appears to be controlled by the crystal-glass interface reaction. The maximum nucleation rate temperature is, also, the same. With respect to the Li2O.2SiO2 glass, the crystal growth activation energy, E(c), is slightly greater and the DTA devitrification peaks are shifted towards lower temperatures. If T(p) is the devitrification peak temperature on a DTA curve recorded under conveniently selected experimental conditions, a dimensionless parameter, E(c)/RT(p), can be defined which can be used to compare the devitrification tendency of different glass compositions. The glass studied has a greater value of E(c)/RT(p) with respect to the parent glass and in the light of the present work thus shows a lower thermal stability.