Hydrogen permeability in (CeO2)0.9(CaO)0.1 at high temperatures

Y. Nigara, J. Mizusaki, K. Kawamura, T. Kawada, M. Ishigame

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24 Citations (Scopus)

Abstract

It was found that hydrogen permeated the bulk of the fluorite-type (CeO2)0.9(CaO)0.1 at 1075-1800 K. Two tube shaped specimens of different lengths were prepared. The hydrogen source gas was H2(7.8%) + N2 which was humidified at 293 K and supplied to the outside of specimens. Ar gas was let flow to the inside of specimens and the permeated hydrogen in the outlet Ar gas was analyzed by a gas chromatograph. Measurements were made at the same conditions on the specimens to eliminate the hydrogen permeated through Pt rings, which were used to fix the specimen, the alumina tube and disk, and the alumina supporting materials. The permeability, JH, in log(JH/mol h-1 cm-1) was almost proportional to 1/T (T: temperature). The gradient of the line changes at 1525 K. The activation energy, E, of conductive protons or electrons was estimated from the Arrhenius' relation, log JH = A - E/2.303 kT. A is constant and E is the activation energy, which is 1.07±0.03 eV above 1525 K and 0.73±0.06 eV below 1525 K, respectively. The electronic activation energies, which were determined from the oxygen permeability, were higher than the above values, and they might be the activation energy of protons. There is a possibility that (CeO2)0.9(CaO)0.1 is an electron-proton mixed conductor under H2-H2O atmosphere at high temperature.

Original languageEnglish
Pages (from-to)347-354
Number of pages8
JournalSolid State Ionics
Volume113-115
DOIs
Publication statusPublished - 1998 Dec 1

Keywords

  • Activation energy
  • Calucia
  • Ceria
  • Electron-proton mixed conductor
  • Fluorite-type structure
  • Hydrogen permeability

ASJC Scopus subject areas

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

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