Activation energy of crystal growth in PbTiO 3 glass using differential thermal analysis

Abstract

The crystallization mechanism in the PbO–TiO 2–B 2O 3–BaO lead titanate glass system was investigated to determine the activation energy ( E) of crystallization using differential thermal analysis (DTA). Two main exothermic peaks were observed in the DTA measurements, which were attributed to the formation of PbTiO 3 and barium–titanium–borate (BTB) phases. Bulk crystallization dominated in PbTiO 3 crystal growth, whereas the BTB phase showed one-dimensional growth from surface to bulk. Kissinger plots for the crystallization peaks ( T p) of PbTiO 3 showed a good linearity between ln( φ/ T p 2) ( φ: heating rate) and 1/ T p, but the slope ( E/R) of the line changed with nucleation conditions and remained constant for fully nucleated glass samples. The activation energies of crystal growth for the lead titanate and the BTB phases were estimated to be about 276 kJ mol −1 and 218 kJ mol −1, respectively. Glass powders under 43 μm did not show the same value of activation energy due to a dominant bulk crystallization creating nano-size crystallites. The activation energy of crystallization was also affected by a change in composition.