Hydrogen permeability of YSZ single crystals at high temperatures

Y. Nigara, Keiji Yashiro, J. O. Hong, Tatsuya Kawada, J. Mizusaki

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The atomic hydrogen (H) permeability, JH, of 10YSZ single crystal (fluorite-type) was measured at 1800-1050 K using the Nigara-method. Two tubular specimens (φ 1.30×0.93 cm; length: 3.35 cm (Specimen(L)) and 1.00 cm (Specimen(S))), annealed at 1570 K for 6 h in air, were used to eliminate the permeations of supporting materials (Pt rings, alumina tube, and alumina disk). Measurement was carried out after the specimen had been kept at 1800 K for 20 h. The JH was 3.97×10-7-2. 79×10-9/mol h-1 cm-1, when it was assumed that PH22=7.36×103 Pa and PH2 O=2.30×103 Pa outside of both specimens and that the Ar flow rates to the inside of Specimen(L) and Specimen(S) were 21.5 and 16.9-19.9 cm3 min-1, respectively. Log JH decreased with the decrease of temperature and was proportional to the inverse temperature. The activation energies were 0.61±0.09, 1.60±0.05, and 0.79±0.02 eV at 1800-1680, 1680-1330, and 1330-1050 K, respectively. The protonic conductivity, which was roughly calculated from the JH and the hydrogen partial pressures inside and outside of the specimens, was 2.4×10-6-1.5×10-8/S cm-1 at 1800-1050 K. The JH of other 10YSZ single crystal specimens, which were not annealed and which were measured after being kept at 1800 K for 1 h, was lower than that of the above specimens, especially at high temperatures, and the activation energies were 1.27±0.03, 0.15±0.03, and 1.49±0.09 eV at 1800-1425, 1425-1150, and 1150-1050 K, respectively. The 10YSZ single crystal would be an electron-proton mixed conductor under H 2-H2O atmosphere at high temperatures. Since the J H of 12YSZ single crystal specimens, which were annealed at 1870 K for 24 h in air and were measured after being kept at 1800 K for 18 h, was less than 1×10-9/mol h-1 cm-1 at 1800 K, it was difficult to determine the relation between its hydrogen permeability and temperature.

Original languageEnglish
Pages (from-to)61-67
Number of pages7
JournalSolid State Ionics
Volume171
Issue number1-2
DOIs
Publication statusPublished - 2004 Jun 30

Keywords

  • Electron-proton mixed conductor
  • Hydrogen permeability
  • YSZ single crystal

ASJC Scopus subject areas

  • Electrochemistry
  • Physical and Theoretical Chemistry
  • Energy Engineering and Power Technology
  • Materials Chemistry
  • Condensed Matter Physics

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