Re-examination of effects of nucleation temperature and time on glass crystallization

The effects of nucleation temperature and time on the kinetics of non-isothermal glass crystallization have been re-examined to demonstrate the limitations of some approximate solutions used to extract kinetic parameters from differential thermal analysis (DTA) experiments. Those features were analyzed by numerical solutions of equations describing the dependence of fraction crystallized on the rates of nucleation and growth, and the corresponding transient time, reported for lithium disilicate. It was shown that the temperature of maximum nucleation rate varies on changing the nucleation time. Some guidelines were established to assist the selection of suitable conditions to perform crystallization studies by DTA, and to extract the values of activation energy and dimensionality of growth from the dependences of crystallization peak temperature on heating rate, and nucleation time. The main limitations of these methods were identified and discussed.