Effect of Nucleation Agent on the Crystallization of Li_2O-Al_2O_3-SiO_2 System Glass

The effect of 4wt%TiO2 and 2wt%TiO2+2wt%ZrO2 on the nucleation and crystallization of Li2O- Al2O3-SiO2 system glass was investigated by the method of differential thermal analysis (DTA), the differential thermal analysis (DTA), X-ray diffraction (XRD) and the scanning electron microscopy (SEM). As the glass nucleates with a different thermal schedule, the crystallization peak temperatures all shift to lower temperatures. The changes of nucleation temperature and nucleation peak height of the glass added with single TiO2 are larger than that of the glass added with TiO2+ZrO2. That means when TiO2 is used as nucleation agent, crystallization is more sensitive as the variation of nucleation temperature than that of the glass added with TiO2+ZrO2. As all nucleation time is 2h, when TiO2 is used as nucleation agent, the most effective nucleation temperature is 745℃, when TiO2+ZrO2 is used as nucleation agent, the most effective nucleation temperature is 760℃. When heat treated at most effective thermal schedule, the samples have grain sizes of 100-150nm for TiO2 as nucleation agent, and of 50~80nm for TiO2 +ZrO2 as nucleation agent.