Defect structure and n-type electrical properties of SrCe0.95Eu0.05O3-δ

The effect of defect structure on the electrical conductivity for Eu-doped SrCeO3 was studied in a reducing range of P-H2, P-H2O, P-O2. A defect model was derived and verified by computational simulation against both electrical conductivity data and Brouwer-type defect equilibria. At higher temperatures, part of the conductivity was due to oxygen vacancies and electrons. At low temperature, protonic conduction dominated. The measured total conductivity is proportional to P-O2(-1/8) in the temperature range of 650-750degreesC, and to P-O2(-1/6) at 800degreesC in wet atmospheres, because of a transition from ionic- to electronic-dominant conduction. The results agree with a derived defect model based on the equilibrium equation for the valence change of Eu ions between trivalent and divalent. (C) 2003 The Electrochemical Society.