Chemical stability and electrical property of Ba1.03Ce0.6Zr0.2Yb0.2O3-α ceramic

Ba1.03Ce0.6Zr0.2Yb0.2O3-α ceramic was prepared by solid state reaction. Phase composition, surface and cross-section morphologies of the material were characterized by using X-ray diffractometer （XRD） and scanning electron microscopy （SEM）, respectively. Its chemical stability against carbon dioxide and water steam at high temperature was tested. Ionic conduction of the material was investigated by ac im-pedance spectroscopy and gas concentration cell methods under different gas atmospheres in the temperature range of 500-900 ℃. Using the ceramic as solid electrolyte and porous platinum as electrodes, the hydrogen-air fuel cell was constructed, and the cell performance at the tem-perature from 500 to 900 oC was examined. The results indicated that Ba1.03Ce0.6Zr0.2Yb0.2O3-α was a single-phase perovskite-type ortho-rhombic system, with high density and good chemical stability under carbon dioxide and water steam atmospheres at high temperature. In wet hydrogen, the material was a pure protonic conductor with the protonic transport number of 1 from 500 to 700 ℃, a mixed conductor of pro-ton and electron with the protonic transport numbers of 0.945-0.916 from 800 to 900 ℃. In wet air, the material was a mixed conductor of proton, oxide ion and electronic hole. The protonic transport numbers were 0.013-0.003, and the oxide ionic transport numbers were 0.346-0.265. Under hydrogen-air fuel cell conditions, the material was a mixed conductor of proton, oxide ion and electron, the ionic trans-port numbers were 0.945-0.848. The fuel cell could work stably, and at 900 ℃, the maximum power output density was 36.5 mW/cm^2.