Glass compositions with formula (71.78-x)SiO2?2.63Al2O3?(2.63+x)K2O?23.7 Li2O (mol.%, x = 0-10) and SiO2/Li2O molar ratios far beyond that of stoichiometric lithium disilicate (LD; Li2Si2O5) were prepared by conventional melt-quenching technique to investigate the influence of K2O content on structure and devitrification behaviour of glasses in the Li2O–SiO2 system. The scanning electron microscopy (SEM) examination of as cast non-annealed glasses revealed the presence of nanosized droplets in glassy matrices suggesting the occurrence of liquid-liquid phase separation. The mean droplet size increased with increasing x values, suggesting that the energy barrier toward phase separation was diminishing due to the lowering of glass melt viscosity. Density measurements, magic angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopy, dilatometry and differential thermal analysis (DTA) were used to assess the influence of K2O on structure-property relationships. LD crystallized from the heat treated glasses with x ? 1, while lithium metasilicate (LS; Li2SiO3) was formed for x > 1.
Revised: November 8, 2011 |
Published: February 1, 2012
Citation
Fernandes H.R., D.U. Tulyaganov, A. Goel, and J.M. Ferreira. 2012.Effect of K2O on structure-property relationships and phase transformations in Li2O?SiO2 glasses.Journal of the European Ceramic Society 32, no. 2:291-298.PNNL-SA-79038.doi:10.1016/j.jeurceramsoc.2011.09.017