Zirconium incorporation into CaTiO3 perovskite prepared from xerogels and implication for the fate of (Ca, Sr) TiO3 nuclear waste ceramics

Nissim U. Navi, Giora Kimmel, Guy Yardeni, Jacob Zabicky, Roni Z. Shneck, Moshe H. Mintz, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

Abstract

CaTiO3 perovskite has been proposed as a ceramic waste form for immobilization of 90Sr. Nonradioactive coprecipitated xerogel powders with nominal atomic ratios of Ca:Zr:Ti = 0.75:0.25:1.00 were synthesized to mimic the fate of (Ca0.7590Sr0.25)TiO 3 solid solution after complete decay of the Sr and its intermediate product Y to stable Zr when an excess B4+ (Ti and 90Zr) cations will present. Ca:Ti = 1.00:1.00 samples were used as a reference. The powders were heated to various conditions to explore the thermodynamic stability of its oxides. The heated Ca:Zr:Ti = 0.75:0.25:1.00 samples formed a major orthorhombic Ca(Zr1-xTix)O3 perovskite phase. The Ti/(Ti + Zr) ratio of the perovskite preserves its nominal ratio at 600°C. The Zr rejects from the Ca(Zr1-xTix)O 3 with further increasing the temperature, following the formation of Ca-Ti-Zr-O secondary phases. This study indicates a tendency of the Zr to segregate from an original (Ca,Sr)TiO3 waste form when the stoichiometry is controlled by the conversion of Sr to Zr (in normal oxidation states).

Original languageEnglish (US)
Pages (from-to)2644-2650
Number of pages7
JournalJournal of the American Ceramic Society
Volume96
Issue number8
DOIs
StatePublished - Aug 2013
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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