Thermochemistry of (Ca xSr 1-x) TiO 3, (Ba xSr 1-x) TiO 3, and (Ba xCa 1-x) TiO 3 perovskite solid solutions

Nissim U. Navi, Roni Z. Shneck, Tatiana Y. Shvareva, Giora Kimmel, Jacob Zabicky, Moshe H. Mintz, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

High-temperature solution calorimetry in molten 3Na 2O• 4MoO 3 solvent at 975 K is used to measure the enthalpy of mixing of (Ca xSr 1-x)TiO 3 and (Ba xSr 1-x)TiO 3 solid solutions. Both solid solutions show positive enthalpy of mixing, however, the (Ba xSr 1-x) TiO 3 shows less deviation from ideality, with interaction parameter λ = 8.5 ± 3.8 kJ/mol, than (Ca xSr 1-x) TiO 3 with interaction parameter λ = 25.3 ± 2.0 kJ/mol. The smaller interaction parameter of the (Ba xSr 1-x) TiO 3 system is attributed to the volume mismatch of the end-members. The larger interaction parameter of (Ca xSr 1-x)TiO 3 may be related to larger ionic radius difference of Ca and Sr and may also reflect the additional energy needed to overcome the lattice distortion of the orthorhombic CaTiO 3 to incorporate it into the cubic perovskite SrTiO 3. (Ba xCa 1-x)TiO 3 has a large positive heat of mixing and limited solid solubility as derived from its phase diagram. This study indicates the tendency of SrTiO 3 and BaTiO 3 to separate from a CaTiO 3 host matrix, which may be significant in perovskite-bearing nuclear waste ceramics incorporating 90Sr and 137Ba.

Original languageEnglish (US)
Pages (from-to)1717-1726
Number of pages10
JournalJournal of the American Ceramic Society
Volume95
Issue number5
DOIs
StatePublished - May 2012
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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