Electrical properties of p-type electronic defects in the Protonic conductor SrCe0.95Eu0.05O3-δ

The electrical properties of SrCe0.95Eu0.05O3-delta were studied as a function of both oxygen partial pressure and water vapor partial pressure in the temperature range of 500-800degreesC, and the partial conductivities of protons, holes, and oxygen vacancies were calculated from the proposed defect model. P-type conduction was dominant in an oxidative atmosphere. It was shown that, in a wet atmosphere, SrCe0.95Eu0.05O3-delta is a mixed conductor of protons, holes, and oxygen ions. A conduction transition from protons to holes and/or oxygen ions was found as temperature increased. The calculated activation energy of oxygen ion transport was 0.67 eV; standard solution enthalpy of water dissolution was -164 kJ/mole, which is larger than that of SrCe0.95Yb0.05O3-delta. The effect of dopants on the conduction mechanism is explained by a hopping mechanism. (C) 2003 The Electrochemical Society.