High-temperature protonic conduction in LaFeO3-SrFeO 3-δ-SrZrO3 solid solutions

Atsushi Unemoto, Atsushi Kaimai, Kazuhisa Sato, Naoto Kitamura, Keiji Yashiro, Hiroshige Matsumoto, Junichiro Mizusaki, Koji Amezawa, Tatsuya Kawada

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1 Citation (Scopus)

Abstract

The electrical conductivity of a pseudoternary system, consisting of LaFeO3-SrFeO3-δ-SrZrO3, { La 0.05 (1-x) Sr0.95+0.05x } (Zr0.95 Fe 0.05)O3-δ (x=0-0.5), was evaluated both in oxygen and hydrogen containing environments by a two-probe ac technique. Correlations of oxygen partial pressure, water vapor pressure, and composition dependences of the electrical conductivities with possible defect concentrations are examined by a semiquantitatively derived Brouwer diagram. In oxygen for x below 0.25, major carriers were identified to be oxide ions and electron holes, while for x=0.5 they were a mixture of oxide ions, electron holes, and protons. In a hydrogen containing environment, the oxides with compositions for x=0.25 and 0.5 were unstable. Thus, the electrical conductivity was analyzed in detail for x=0.1. It was found that the oxide conducts protons significantly at temperatures below 1273 K, which was evidenced by the isotope effect of hydrogen and deuteron on the electrical conductivity. The electrical conductivity of the oxide increased with decreasing oxygen partial pressure due to the variation of oxygen nonstoichiometry, accompanied by partial reduction of Fe ions in the oxide. The transport number of proton increased as the oxygen partial pressure decreased. The gas partial pressure and the composition dependences of the electrical conductivity and the transport number of proton could be well explained by the conceptual Brouwer diagram proposed in this work.

Original languageEnglish
JournalJournal of the Electrochemical Society
Volume158
Issue number2
DOIs
Publication statusPublished - 2011 Jan 5

ASJC Scopus subject areas

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

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