Effect of K2O on structure-property relationships and phase transformations in Li2O-SiO2 glasses

Hugo R. Fernandes, Dilshat U. Tulyaganov, Ashutosh Goel, José M.F. Ferreira

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Abstract

Glass compositions with formula (71.78-x)SiO2-2.63Al2O3-(2.63+x)K2O-23.7Li2O (mol.%, x=0-10) and SiO2/Li2O molar ratios far beyond that of stoichiometric lithium disilicate (Li2Si2O5) were prepared by conventional melt-quenching technique to investigate the influence of K2O content on structural transformations 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 occurrence of liquid-liquid phase separation. An overall trend towards depolymerization of the silicate glass network with increasing K2O content was demonstrated by employing magic angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopy. The distribution of structural units in the experimental glasses was estimated using 29Si MAS-NMR spectroscopy suggesting the appearance of Q2, enhancement of Q3 and diminishing of Q4 groups with increasing K2O contents. X-ray diffraction (XRD) and differential thermal analysis (DTA) were used to assess the influence of K2O on devitrification process and formation of lithium disilicate (Li2Si2O5) and/or lithium metasilicate (Li2SiO3) crystalline phases.

Original languageEnglish (US)
Pages (from-to)291-298
Number of pages8
JournalJournal of the European Ceramic Society
Volume32
Issue number2
DOIs
Publication statusPublished - Feb 1 2012

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All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Materials Chemistry

Keywords

  • Glass
  • Glass ceramics
  • Lithium disilicate
  • Thermo-physical properties

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