Samples of 25mol%Y3+-doped BaCeO3 exhibited an extremely low activation energy (0.3eV) for proton conduction at the surface. The resultant overall conductivity at the surface reached 0.00824S/cm at 400C. This was 3, 8 and 28 times higher than those in the bulk of 25mol%Y3+-doped BaCeO3, 20mol% Sm3+-doped ceria, and 8mol% yttria-stabilized zirconia, respectively.

Proton Conduction at the Surface of Y-Doped BaCeO3 and its Application to an Air/Fuel Sensor. A.Tomita, T.Hibino, M.Suzuki, M.Sano: Journal of Materials Science, 2004, 39[7], 2493-7