The atomic H (1/2H2) permeability, JH, in (CeO2)0.9(GdO1.5)0.1 (fluorite-type) was measured at 1800 to 800K. Two tubular specimens (SP(L), SP(S)) of different lengths sintered at 1970K in air were used to eliminate the permeation through supporting materials (Pt rings, alumina tube and alumina disk). The JH was 2.81 x 10-6 to 1.50 x 10-8/mol/hcm, when it was assumed that PH2 = 7.34 x 103Pa and PH2O = 2.28 x 103Pa 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 to 16.0cm3/min, respectively. Log[JH] decreased with decreasing temperature and was proportional to the inverse temperature at 1800 to 1100 and 1100 to 800K, and the activation energies were 1.12 and 0.18eV, 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 H partial pressures inside and outside the specimens, its values being 1.4 x 10-4–7.2 x 10-7S/cm and 1.2 x 10-6S/cm at 1070K.

Hydrogen Permeability in (CeO2)0.9(GdO1.5)0.1 at High Temperatures. Y.Nigara, K.Yashiro, T.Kawada, J.Mizusaki: Solid State Ionics, 2003, 159[1-2], 135-41