Thermochemical study of trivalent-doped ceria systems: CeO2-M O1.5 (M = La, Gd, and Y)

Weiqun Chen, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

The formation enthalpies from the oxide end-members (ΔHf,ox) of the CeO2-MO1.5 (M = La, Gd, and Y) systems were determined by high temperature oxide melt drop solution calorimetry. In each system, ΔHf,ox is slightly positive over the investigated composition range with a maximum at a certain doping level. Above that concentration, ΔHf,ox decreaseses rapidly and stays almost constant. Such behavior is strikingly different from the strongly negative ΔHf,ox of the ZrO2-YO1.5 and HfO2-YO1.5 systems. The absence of substantial energetic stabilization in the CeO2-MO1.5 systems may be attributed to the large size of Ce4+, which has no preference for 7-coordination like the smaller Zr4+ or Hf4+ ions. The primary defect associates in CeO2-MO1.5 are proposed to be neutral trimers with oxygen vacancies nearest neighbor to the dopant cations. It is also suggested that the maximum ΔHf,ox (destabilization) of CeO2-M O1.5 is determined by the local site distortion rather than the global lattice deformation. The relatively stable region after the maximum ΔHf,ox may be attributed to the somewhat stabilizing long-range defect-defect interactions, which become effective above a certain doping level.

Original languageEnglish (US)
Pages (from-to)3242-3251
Number of pages10
JournalJournal of Materials Research
Volume21
Issue number12
DOIs
StatePublished - Dec 2006
Externally publishedYes

ASJC Scopus subject areas

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

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