We have investigated the crystallization mechanism of the lithium disilicate (Li2O-2SiO2, LSO) glass particles with different sizes by isothermal and non-isothermal processes. The LSO glass was fabricated by rapid quenching of melt. X-ray diffraction and differential scanning calorimetry measurements were performed. Different crystallization models of Johnson- Mehl-Avrami, modified Ozawa and Arrhenius were adopted to analyze the thermal measurements. The activation energy E and the Avrami exponent n, which describe a crystallization mechanism, were obtained for three different glass particle sizes. Values of E and n for the glass particle with size under 45 μm, 75~106 μm, and 125~150 μm, were 2.28 eV, 2.21 eV, 2.19 eV, and ~1.5 for the isothermal process, respectively. Those values for the non-isothermal process were 2.4 eV, 2.3 eV, 2.2 eV, and ~1.3, for the isothermal process, respectively. The obtained values of the crystallization parameters indicate that the crystallization occurs through the decreasing nucleation rate with a diffusion controlled growth, irrespective to the particle sizes. It is also concluded that the smaller glass particles require the higher heat absorption to be crystallized.

A Li2O-2SiO2 (LS2) glass was investigated as a lithium-ion conducting oxide glass, which is applicable to a fast ionic conductor even at low temperature due to its high mechanical strength and chemical stability. The Li2O-2SiO2 glass is likely to be broken into small pieces when quenched; thus, it is difficult to fabricate a specifically sized sample. The production of properly sized glass samples is necessary for device applications. In this study, we applied spark plasma sintering (SPS) to fabricate LS2 glass samples which have a particular size as well as high transparency. The sintered samples, 15mmφ×2mmT in size, (LS2-s) were produced by SPS between 480˚C and 500˚C at 45MPa for 3~5mim, after which the thermal and dielectric properties of the LS2-s samples were compared with those of quenched glass (LS2-q) samples. Thermal behavior, crystalline structure, and electrical conductivity of both samples were analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and an impedance/gain-phase analyzer, respectively. The results showed that the LS2-s had an amorphous structure, like the LS2-q sample, and that both samples took on the lithium disilicate structure after the heat treatment at 800˚C. We observed similar dielectric peaks in both of the samples between room temperature and 700˚C. The DC activation energies of the LS2-q and LS2-s samples were 0.48±0.05eV and 0.66±0.04eV, while the AC activation energies were 0.48±0.05eV and 0.68±0.04eV, respectively.