Nucleation and crystallization behavior of Li2O-Al2O3-SiO2 system glass-ceramic containing little fluorine and no-fluorine

The nucleation and crystallization behavior of Li2O-A1(2)O(3)-SiO2 system (LAS) glass-ceramics containing little fluorine and nofluorine are investigated by the differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). TEM of the annealed glass shows that the nucleation has appeared during the annealing stage. DTA of pre-nucleated glass shows that the optimum nucleating temperature of the LAS glass containing fluorine is 620 degrees C and 40 degrees C lower than that containing no-fluorine. XRD and SEM show that the optimum crystallizing temperature of the LAS glass containing fluorine is 760 degrees C, 110 degrees C lower than that containing no-fluorine, and the optimum crystallizing time is 4 h. The introduction of fluorine can decrease the crystallizing peak temperature (T-p) and the crystallizing activation energy (E) and improve the crystallization stage to obtain fine crystal with a size of 150 nm. (c) 2005 Elsevier B.V. All rights reserved.