Thermodynamic behavior of various phases appearing in the CeZrO4-CeZrO3.5 system and the formation of metastable solid solutions

Shinya Otsuka-Yao-Matsuo, Noriya Izu, Takahisa Omata, Katsuhiko Ikeda

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

In order to investigate the thermodynamic behavior of t́, t*, and κ phases with the composition, CeZrO4, the equilibrium oxygen partial pressure, pO2, over their mixtures with pyrochlore (Ce2Zr2O7+x) was measured utilizing an electrochemical cell: Pt, {CeZrO4(t′, t*, or κ phase) + Ce2Zr2O7+x}/ZrO2(+Y 2O3)/air, Pt. The conclusions described below were derived: the thermodynamic stability of the κ phase is the lowest in the CeO2-ZrO2 system. The κ phase forms metastable solid solutions with the pyrochlore phase; it was virtually stable around 1123 K. Two kinds of tetragonal phases exist, tet. (high temp.) and tet. (low temp.), which may correspond to t′ and t*, respectively. A change in pO2 corresponding to the phase transitions: κ → t′ and t′ ⇄ t* was observed. The standard Gibbs energies of formation, ΔG°, of κ(CeZrO4) and t*(CeZrO4) for the reaction: 1/2Ce2Zr2O7 + 1/4 O2 → CeZrO4 were evaluated from the emf data.

Original languageEnglish
Pages (from-to)1406-1413
Number of pages8
JournalJournal of the Electrochemical Society
Volume145
Issue number4
DOIs
Publication statusPublished - 1998 Apr
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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