The atomic hydrogen (1/2H2) permeability, JH, in (CeO2)0.9(GdO1.5)0.1 (fluorite-type) was measured at 1800-800 K. Two tubular specimens (SP(L), SP(S)) of different lengths sintered at 1970 K in air were used to eliminate the permeation through supporting materials (Pt rings, alumina tube and alumina disk). The JH was 2.81 × 10-6-1.50 × 10-8/mol h-1 cm-1, when it was assumed that PH2=7.34 × 103 Pa and PH2O=2.28 × 103 Pa outside of both specimens and that the Ar flow rates to the inside of SP(L) and SP(S) were 20.9 and 9.4-16.0 cm3 min-1, respectively. LogJH decreased with decreasing temperature and was proportional to the inverse temperature at 1800-1100 and 1100-800 K, and the activation energies were 1.12 ± 0.01 and 0.18 ± 0.01 eV, respectively. (CeO2)0.9(GdO1.5)0.1 would be an electron-proton mixed conductor under H2-H2O atmosphere at high temperatures. The protonic conductivity was roughly calculated from the JH and from the hydrogen partial pressures inside and outside the specimens, its values being 1.4 × 10-4-7.2 × 10-7/S cm-1 and 1.2 × 10-6/S cm-1 at 1070 K.
- Electron-proton mixed conductor
- Fluorite-type oxide
- Hydrogen permeability