The atomic H permeability, JH, in fluorite-type (CeO2)0.85(CaO)0.15 was measured to confirm the influence of CaO concentration in CeO2 at 1050 to 1800K. The decrease of JH with reducing temperature and the proportionality of log JH to inverse temperature were suggested. The estimated activation energies were 1.0, 1.3 and 0.2eV at 1800 to 1400, 1400 to 1250 and 1250 to 1050K, respectively. The JH of (CeO2)1-X(CaO)X decreased with increasing X and proportional to X5/2 at 1800 to 1300K under H2–H2O atmosphere. H2 was decomposed to 2H+ and 2e- on the surface of the specimen and they permeate it. They hop between O ions and Ce ions, respectively. It would be difficult for H+ to cross over Vö, which was produced by CaO, then JH decreased with increasing X. (CeO2)1-x(CaO)x would be the electron–proton mixed conductor under H2–H2O atmosphere at high temperatures.

The Atomic Hydrogen Permeability in (CeO2)0.85(CaO)0.15 at High Temperatures. Y.Nigara, K.Yashiro, T.Kawada, J.Mizusaki: Solid State Ionics, 2001, 145[1-4], 365-70