Crystallization of Li2O-2SiO2 Glass under High Hydrostatic Pressures
The concentration of nuclei (Nv) in a Li2O.2SiO2 (LS2) glass was measured using a newly developed differential thermal analysis technique, after densifying the glass at 1,3, or 6 GPa pressure at 400oC for 20 min. Nv increased from 38 x 1012 m-3 for an asmelted glass to 82 x 1012 m-3 for a glass subjected to a pressure of 1 GPa, and remained nearly constant with further increase of pressure of up to 6 GPa. This increase in Nv is equivalent to nucleating this LS2 glass at the temperature (455oC) of its maximum nucleation rate for 2 h. the average effective activation energy for crystallization for the densified glasses, 292 ± 10 kJ/mol, was also the same as that for an as-melted (undensified and unnucleated) glass. the present results show that applying an external pressure on this LS2 glass shifts its nucleation curve to lower temperatures causing nuclei to form even at 400oC. a decrease in viscosity at all temperatures with the application of pressure is suspected to be a reason for the enhanced nucleation observed for this LS2 glass.
T. Fuss et al., "Crystallization of Li2O-2SiO2 Glass under High Hydrostatic Pressures," Melt Chemistry, Relaxation, and Solidification Kinetics of Glasses: Proceedings of the 106th Annual Meeting of the American Ceramic Society (2004, Indianapolis, IN), USA 2004, Ceramic Transactions, Volume 170, John Wiley & Sons, Jan 2004.
The definitive version is available at http://dx.doi.org/10.1002/9781118408063.ch16
106th Annual Meeting of the American Ceramic Society (2004, Indianapolis, IN)
Materials Science and Engineering
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Article - Conference proceedings
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