Crystallization Kinetics for Synthesis Hyper-Structure in P_2O_5-ZnO-B_2O_3-BaO-Al_2O_3-TiO_2 Glass Ceramic Composite

摘要

The nucleation and crystallization kinetics of P_2O_5-B_2O_3-ZnO-BaO-Al_2O_3-TiO_2 crystals in bulk glass in which this crystals were found to crystallize in the heating process of the glass, were studied by non-isothermal measurements using differential thermal analysis (DTA). A nucleation rate-temperature was determined by plotting either the reciprocal of the temperature corresponding to the crystallization peak maximum, I/T_p, or the height of the crystallization peak, (△T)_p, as a function of nucleation temperature, T_n. The temperature where nucleation can occur for this glass ranges from 700°C to 890°C and the temperature for maximum nucleation is 760±5°C. The correct activation energy for crystallization, E_c, for this glass is the same for surface and/or bulk crystallization, and is 533±15°CkJ/mol. The analysis of the crystallization data with the Kissinger equation and the Marotta equation yields the correct value for E_c only crystal growth occurs on a fixed number of nuclei. The crystallization process of a sample heat treated at the temperature of the maximum nucleation rate was fitted to kinetic equations with an Avrami constant, n ≈2 and a dimensionality of crystal growth, m ≈2.