Thermochemistry of substituted perovskites in the NaTixNb1-xO3-0.5x System

Hongwu Xu, Alexandra Navrotsky, M. Lou Balmer, Yali Su

Research output: Contribution to journalConference articlepeer-review

2 Scopus citations

Abstract

A suite of perovskite phases with the compositions NaTixNb1-xO3-0.5x, 0 ≤ x ≤ 0.2, has been synthesized for the first time using the sol-gel method. Rietveld analysis of powder XRD data reveals that with increasing Ti content, the orthorhombic perovskite structure becomes more cubic-like, as evidenced by the smaller differences among its three cell parameters. Enthalpies of formation of the synthesized phases from the constituent oxides and from the elements have been determined by drop solution calorimetry into molten 3Na2O·4MoO3 solvent at 974 K. As Ti4+ substitutes for Nb5+, the formation enthalpies become less exothermic in a nearly linear manner. This behavior suggests that the Ti→Nb substitution destabilizes the perovskite structure, presumably because of the concomitant occurrence of O2+ vacancies, which compensate the charge imbalance between Ti4+ and Nb5+ in the structure.

Original languageEnglish (US)
Pages (from-to)65-70
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume718
DOIs
StatePublished - 2002
Externally publishedYes
EventPerovskite Materials - San Francisco, CA, United States
Duration: Apr 1 2002Apr 5 2002

ASJC Scopus subject areas

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

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