The origin of elastic anomalies in thin films of oxygen deficient ceria, CeO2 - X

Anna Kossoy, Anatoly I. Frenkel, Yishay Feldman, Ellen Wachtel, Alla Milner, Igor Lubomirsky

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Abstract

Self-supported films of CeO1.95 display time-scale dependent elastic moduli, a phenomenon which has been termed the chemical strain effect. In order to probe the possible structural origins of this behavior, extended X-ray absorption fine structure spectroscopy and X-ray diffraction were used. Evidence was found that, although this oxygen deficient ceria appears to maintain the fluorite structure on average, the mean Ce-O bond length is shorter than the mean Ce-oxygen vacancy distance. This finding is consistent with crystallographic data from more strongly reduced ceria in which the oxygen vacancies are ordered. By studying strain induced structural changes, we show that it is possible to relate this lattice distortion to the chemical strain effect. Similar conclusions were previously reached for films of Ce 0.8Gd0.2O1.9. Since the ionic radii of both Gd3+ and Ce3+ are larger than that of Ce4+, we suggest that when cation dopants are larger than the host, ceria compounds containing a high concentration of oxygen vacancies may exhibit elastic anomalies.

Original languageEnglish
Pages (from-to)1473-1477
Number of pages5
JournalSolid State Ionics
Volume181
Issue number33-34
DOIs
Publication statusPublished - Oct 25 2010

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Keywords

  • Chemical strain
  • Elasticity
  • Extended X-ray absorption fine structure spectroscopy (EXAFS)
  • Gadolinium-doped ceria
  • Thermal expansion

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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