Calorimetric measurements of energetics of defect interactions in fluorite oxides

Alexandra Navrotsky, Petra Simoncic, Harumi Yokokawa, Weiqun Chen, Theresa Lee

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Direct measurement by oxide melt solution calorimetry of energetics of mixing in rare earth and yttrium doped zirconia, hafnia, and ceria systems provides support for spectroscopic and computational studies of the location and clustering of vacancies in these systems. Strongly negative heats of mixing are seen when the vacancy is transferred from being nearest neighbor to Y or RE in the sesquioxide to being nearest neighbor to Zr or Hf in the cubic solid solution. In the absence of such redistribution, small positive enthalpies of mixing are seen in CeO2-YO1.5 and CeO2-REO 1.5 systems. Strongly positive enthalpies of mixing are seen in CeO2-ZrO2, which has a large difference in cation sizes and no vacancy formation. The system Ce0.8Y0.2O 1.9-Zr0.8Y0.2O1.9 shows small positive heats of formation with less destabilization in the Ce-rich region, suggestive of "scavenging" of oxygen vacancies by Zr. The calorimetric data obtained in these studies offer direct comparison with the results of computations on defect clusters and their binding energies.

Original languageEnglish (US)
Pages (from-to)171-180
Number of pages10
JournalFaraday Discussions
Volume134
DOIs
StatePublished - 2007
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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