Energetics of silica-poor glasses in the systems MgO - SiO 2 and Mg 0.5 Ca 0.5 O - SiO 2

Nektarios K. Nasikas, Alexandra Navrotsky

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1 Scopus citations

Abstract

A series of alkaline-earth silicate glasses, with compositions ranging from the metasilicate to the ortho- and suborthosilicate, have been synthesized by aerodynamic levitation and CO2 laser melting. They have been studied by high-temperature oxide melt solution calorimetry with 2PbO·B 2O3 as solvent. The enthalpies of formation from the oxides at room temperature (ΔH298K,oxides0,gl) have been calculated from the solution enthalpies. Glasses in the Ca0.5Mg0.5O- SiO2 system show greater energetic stability than those in the MgO-SiO2 system, with a more pronounced negative enthalpy of mixing near the orthosilicate composition. This stabilization may explain why it is possible to prepare glasses poorer in silica (suborthosilicate) in the Ca 0.5Mg0.5O-SiO2 system but not in the MgO-SiO2 system. The thermodynamic observations support earlier structural studies in these systems.

Original languageEnglish (US)
Pages (from-to)451-456
Number of pages6
JournalJournal of the American Ceramic Society
Volume97
Issue number2
DOIs
StatePublished - Feb 2014
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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