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

摘要

The paper investigates the effects of nucleation and crystallization treatments on nano-crystalline lithium-mica glass-ceramics, taking the composition LiMg_3AlSi_(3(1+x))O_(10+6x)F_2 (x = 0.5) and 8 mass% MgF_2 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 MgF_2 crystals perform as nuclei centers for the mica crystallization hence; a large quantity of mica crystallites obtained following the nucleation process at 400 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.