Effect of composition and atmosphere on electrical properties of donor-doped BaCe_1-(x+y)Zr_xNb_yO₃

The properties of donor-doped barium cerate perovskites have recently gained attention as electrode or electrolyte materials for high temperature solid-state devices utilizing CO₂ containing gas streams due to their excellent chemical stability. In this study, the effect of co-doping BaCeO3 with Nb and Zr on electrical conductivity from 300-700 °C in air and in H₂ is investigated. Small doping levels give rise to a significant increase in total conductivity in both air and hydrogen environments compared to BaCeO₃. In air, activation energies for conduction are ∼1 eV. In a reducing environment, the Nb appears to be the species more easily reduced in order to give rise to increased total conductivity, and there is a discontinuous change in total activation energy from ∼0.55 eV to ∼0.3 eV at low temperatures in H₂. The transition temperature is dependent on dopant concentration. These materials may provide chemically-stable mixed conducting anode materials for high temperature proton conductors.