Enthalpy of formation of cubic yttria-stabilized hafnia

Theresa A. Lee, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

The enthalpy of formation of cubic yttria-stabilized hafnia from monoclinic hafnia and C-type yttria was measured by oxide melt solution calorimetry. The enthalpies of formation fit a function independent of temperature and quadratic in composition. The enthalpies of transition from m-HfO2 and C-type YO1.5, to the cubic fluorite phase are 32.5 ± 1.7 kJ/mol and 38.0 ± 13.4 kJ/mol, respectively. The interaction parameter in the fluorite phase is strongly negative, -155.2 ± 10.2 kJ/mol, suggesting even stronger short range order than in ZrO2-YO1.5. Regular solution theory or any other model assuming random mixing on the cation and/or anion sublattice is not physically reasonable. A more complex solution model should be developed to be consistent with the new calorimetric data and observed phase relations.

Original languageEnglish (US)
Pages (from-to)1855-1861
Number of pages7
JournalJournal of Materials Research
Volume19
Issue number6
DOIs
StatePublished - Jun 2004
Externally publishedYes

ASJC Scopus subject areas

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

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