Ionic conduction in BaxCe0.8Pr0.2O3–α

BaxCe0.8Pr0.2O3–α (x=0.98–1.03) ceramics were prepared by high temperature solid-state reaction. X-ray diffraction (XRD) patterns showed that the materials were perovskite-type orthorhombic single phase. By using gas concentration cell and AC impedance spectroscopy methods, the electrical conduction behavior of the materials was investigated in different gases at 500–900 °C. The influence of nonstoichiometry in the materials with x≠1 on conduction properties was studied and compared with that in the material with x=1. The results indicated that Ba1.03Ce0.8Pr0.2O3–α was a pure protonic conductor, and Ba0.98Ce0.8Pr0.2O3–α was a mixed conductor of protons and electrons in wet hydrogen at 500–900 °C. BaCe0.8Pr0.2O3–α was a pure protonic conductor in 500–600 °C, and a mixed conductor of protons and electrons above 600 °C in wet hydrogen. In 500–900 °C, they were all mixed conductors of oxide ions and electronic holes in dry air, and mixed conductors of protons, oxide ions and electronic holes in wet air. Both the protonic and oxide ionic conductivities increased with increasing barium content in the materials in wet hydrogen, dry air and wet air, respectively.