Yttrium substitution in MTiO3 (M=Ca, Sr, Ba and Ca+Sr+Ba) perovskites and implication for incorporation of fission products into ceramic waste forms

Nissim U. Navi, Giora Kimmel, Jacob Zabicky, Sergey V. Ushakov, Roni Z. Shneck, Moshe H. Mintz, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

CaTiO3 has been proposed as a ceramic waste form for immobilization of radioactive waste that might include short-lived fission products 137Cs and 90Sr and consequently their decay products 137Ba (stable), 90Y (intermediate), and 90Zr (stable). In order to characterize substitution relations of Y3+ for M2+ (M=Ca, Sr, Ba singly or in combination) in MTiO3, precursor mixtures with nominal atomic ratios of M:Y:Ti=0.75:0.25:1 were synthesized by solid-state reactions. To ensure homogeneous starting material and to explore low temperature behavior of the Ca-Y-Ti-O system, coprecipitated xerogel powder was synthesized and heated to various temperatures for different periods of time. All M-Y-Ti-O systems formed two major phase mixtures of perovskite MTiO3 and pyrochlore Y 2Ti2O7 with low substitution of M2+ by Y3+ in MTiO3 and Y3+ by M2+ in Y2Ti2O7. The study of xerogel confirmed the tendency of the formation of mixtures of CaTiO3 and Y 2Ti2O7 phases, even at lower temperature. The temperature dependence of the substitution of Ca2+ by Y3+ in CaTiO3 appears to be small. Despite the minor substitution of M by Y in the perovskite no significant 90Y3+ build-up is expected to occur in the waste form due to the rapid decay of 90Y3+ relative to that of 90Sr2+.

Original languageEnglish (US)
Pages (from-to)3112-3116
Number of pages5
JournalJournal of the American Ceramic Society
Volume94
Issue number9
DOIs
StatePublished - Sep 2011
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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