Electrical conduction in SrCeO3 doped with Eu2O3

It was found from Moessbauer spectroscopy that the europium ions in SrCe0.9Eu0.1O3−x annealed at 1273 K in air and hydrogen gas existed as the Eu(III) state. The activation energy of oxide ionic conduction for the Eu-doped sample was smaller than that for the Yb-doped one, probably due to a larger free volume and a larger critical radius at the saddle point. The transport number of oxide ions in SrCe0.9Eu0.1O3−x increased with decreasing temperature and became unity at about 873 K. The electrical conductivity of SrCe0.9Eu0.1O3−x increased with increasing hydrogen partial pressure, indicating a protonic conduction and the activation energy changed at around 1023 K, probably due to water vapor evolution observed by TG–DTA measurement.