Energetics of dissolution of Gd2O3 and HfO2 in sodium alumino-borosilicate glasses

Yahong Zhang, Alexandra Navrotsky, Hong Li, Liyu Li, Linda L. Davis, Denis M. Strachan

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

In addition to their industrial and consumer-oriented applications, sodium alumino-borosilicate glasses are leading candidates for encapsulation of reprocessed commercial and defense-related nuclear waste. Quantification of the thermochemical and physical properties of these glasses is necessary for a complete understanding of processes occurring in these systems. In this study, 16 glass samples were studied including the base glass (20Na2O-15B2O3-5Al2 O3-60SiO2), six Gd-doped glasses (0.45, 0.92, 1.72, 3.25, 4.74, 7.67, 10.53 mol% Gd2O3) and eight Hf-doped glasses (0.15, 0.38, 0.77, 1.57, 3.27, 5.09, 7.06, 11.53 mol% HfO2). Drop solution calorimetry using lead borate solvent at 976 K indicates that these glasses are energetically stable with respect to their binary crystalline oxides. There is a sharp change in the enthalpy of formation between glasses with more than 1.6mol% Gd2O3 or HfO2 addition and glasses of lower Gd2O3 or HfO2 content. At higher doping levels, the apparent partial molar enthalpy of solution of HfO2 in the glass is close to zero, consistent with the formation of nanometer-sized heterogeneities. A possible explanation is that glasses with more than 1.6 mol% added oxides consist of regions of Gd2O3 or HfO2-rich glass perhaps containing regions of medium-range order dominated by Gd2O3 or HfO2 and/or their nanocrystals and regions of Gd2O3 or HfO2 poor glass. Glass transition temperatures from DSC experiments indicate similar trends with a change in slope near 1.6mol% Gd2O3 or HfO2. These data are consistent with structural and spectroscopic studies that suggest the onset of clustering and related changes in structure in this composition range.

Original languageEnglish (US)
Pages (from-to)93-101
Number of pages9
JournalJournal of Non-Crystalline Solids
Volume296
Issue number1-2
DOIs
StatePublished - Dec 2001
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Materials Chemistry

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