Effect of TiO2 addition on the crystallization of Li2O-Al2O3-4SiO(2) precursor powders by a sol-gel process

The activation energy for crystallization of beta-spodumene in TiO2 added L i2O-Al2O3-4SiO(2) (LAS) precursor powders by a sol-gel process was studied by using isothermal and nonisothermal methods. Nonisothermal kinetics for t he LAS precursor powder system were investigated using differential thermal analysis (DTA) and quantitative x-ray diffraction (XRD) analysis. The rate of crystallization of LAS precursor powders decreased as the TiO2 content increased. For samples with addition of 0, 5.0, and 10.0 wt% TiO2, the acti vation energies for crystallization by DTA evaluation were 165.06, 194.46, and 205.38 kJ/mol, respectively. According to the quantitative XRD method, the values computed by the Johnson-Mehl-Avrami equation were 162.54, 189.42 , and 196.14 kJ/mol, respectively. The values obtained by isothermal and no nisothermal kinetic methods from DTA and XRD analyses were in good agreemen t. The growth morphology parameters were 0.59, 0.70, and 0.76, respectively , for the LAS precursor powder with TiO2 addition of 0, 5.0, and 10.0 wt%, showing a rodlike growth. In the LAS precursor powder system, TiO2 did not act as the nucleative agent.