Nucleation and crystallization behaviors of nano-crystalline lithium-mica glass-ceramic prepared via sol-gel method

The paper investigates the effects of nucleation and crystallization treatments on nano-crystalline lithium-mica glass-ceramics, taking the composition LiMg3AlSi3(1+x)O10+6xF2 (x = 0.5) and 8 mass% MgF2 synthesized by sol-gel technique. Here. X-ray diffraction, thermal analysis and transmission electron microscopy were used to assess the structural evolutions of as-synthesized nano-crystalline lithium-mica glass-ceramics. It was found that MgF2 crystals perform as nuclei centers for the mica crystallization hence; a large quantity of mica crystallites obtained following the nucleation process at 400 degrees C for 12 h. For both the un-nucleated and nucleated samples, the crystallization activation energy was measured as 400.2 and 229.6 kJ mol(-1), respectively. Consequently, the calculated Avrami exponents demonstrated that the growth mechanism of mica crystallites, while applying appropriate nucleation treatment, changes from needle-like to three-dimensional growth. (C) 2012 Elsevier Ltd. All rights reserved