Crystallization kinetics in a lithium disilicate glass revisited: Model-free and model-fitting approaches

The present work estimated the crystallization activation energy, E _α , the pre-exponential term, A, and the reaction model, g(α), of a lithium disilicate glass using model-free and model-fitting approaches. Samples with distinct granulometry (PD1: < 105 μm; and PD5: 600–850 μm) were heated at several rates (0.5 to 30 K/min). Our results show that E _α, A, and g(α) are susceptible to particle size. PD1 crystallizes in a single step, and the surface mainly governs it all β values. On the other hand, the overall crystallization of PD5 is more complex and can be described by different Avrami reaction models, with n = 1, 1.5, 2, and 3. In addition, we found that the crystallized fraction at the crystallization peak (α _Tp) varies significantly with the particle size and heating rate, which confirms that all the methods that assume that the α _Tp is constant are inadequate to describe the crystallization of glasses over a wide range of heating rates.