Ionic Conduction in Ba0.95Ce0.8Ho0.2O3−α

Abstract

AbstractBa0.95Ce0.8Ho0.2O3−α was prepared by high temperature solid‐state reaction. X‐ray diffraction (XRD) pattern showed that the material was of a single perovskite‐type orthorhombic phase. Using the material as solid electrolyte and porous platinum as electrodes, the measurements of ionic transport number and conductivity of Ba0.95Ce0.8Ho0.2O3−α were performed by gas concentration cell and ac impedance spectroscopy methods in the temperature range of 600–1000 °C in wet hydrogen, dry and wet air respectively. Ionic conduction of the material was investigated and compared with that of BaCe0.8Ho0.2O3−α. The results indicated that Ba0.95Ce0.8Ho0.2O3−α was a pure protonic conductor with the protonic transport number of 1 during 600–700 °C in wet hydrogen, a mixed conductor of protons and electrons with the protonic transport number of 0.97–0.93 in 800–1000 °C. But BaCe0.8Ho0.2O3−α was almost a pure protonic conductor with the protonic transport number of 1 in 600–900 °C and 0.99 at 1000 °C in wet hydrogen. In dry air and in the temperature range of 600–1000 °C, they were both mixed conductors of oxide ions and electronic holes, and the oxide‐ionic transport numbers were 0.24–0.33 and 0.17–0.30 respectively. In wet air and in the temperature range of 600–1000 °C, they were both mixed conductors of protons, oxide ions and electronic holes, the protonic transport numbers were 0.11–0.00 and 0.09–0.01 respectively, and the oxide‐ionic transport numbers were 0.41–0.33 and 0.27–0.30 respectively. Protonic conductivity of Ba0.95Ce0.8Ho0.2O3−α in both wet hydrogen and wet air was higher than that of BaCe0.8Ho0.2O3−α in 600–800 °C, but lower in 900–1000 °C. Oxide‐ionic conductivity of the material was higher than that of BaCe0.8Ho0.2O3−α in both dry air and wet air in 600–1000 °C.