Thermochemistry of glass forming Y-substituted Sr-analogues of titanite (SrTiSiO5)

Tae Jin Park, Simon Li, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Strontium titanium silicates are possible oxide forms for immobilization of short lived fission products in radioactive waste. Through beta decay, strontium decays to yttrium, and then to zirconium. Therefore, not only the stability of Sr-loaded waste forms, but also that of a potential decay product series with charge-balance in a naturally occurring mineral or a ceramic is of fundamental importance. Strontium titanosilicate (SrTiSiO5) is the Sr-analogue of titanite (CaTiSiO5). To incorporate the reaction 3Sr2+ = 2Y3+ + vacancy in the titanite composition, Y-substituted Sr-analogues of titanite, (Sr1-xY2/3x) TiSiO5 (x = O, 0.25, 0.5, 0.75) were prepared by high temperature synthesis and were found to form glass upon cooling. The Y-end-member (Y 2/3TiSiO5, x = 1) crystallized to a mixture of Y 2Ti2O7, TiO2, and SiO2 upon quenching in air. The enthalpies of formation of Y-substituted Sr-titanite glasses were obtained from drop solution calorimetry in a molten lead borate (2PbOB2O3) solvent at 702 °C. The enthalpies of formation from constituent oxides are exothermic but become less so with increasing Y content. The thermodynamic stability of the Y-substituted Sr-analogue of crystalline titanite may become marginal with increasing yttrium content.

Original languageEnglish (US)
Pages (from-to)3380-3386
Number of pages7
JournalJournal of Materials Research
Volume24
Issue number11
DOIs
StatePublished - Nov 2009
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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