Abstract: Ce0.8Sm0.2O2-δ and Ca3Co2O6-δ powders were synthesized via coprecipitation and citrate complex methods, respectively, followed by sintering in air to achieve the dense Ce0.8Sm0.2O2-δ-Ca3Co2O6-δ dual-phase membrane.The phase composition and the microstructure of the samples were studied by X-ray diffraction patterns (XRD) and field emission scanning electron microscopy (FESEM), respectively.The study was carried out on elucidating of the influences of dual phase ratio on the thermal expansion coefficient, electronic conductivity and oxygen permeability of the dual-phase membrane.The experiment results indicate that the two phases exhibit good chemical stability, and the dense membrane is achieved after sintering at 1150 ℃ for 6 h.The membrane shows low thermal expansion coefficient, as 13.47×10-6 ~14.23×10-6 K-1, which is closed to that of the solid electrolyte.Increasing the ionic phase from 40wt; to 80wt;, the electronic conductivity is decrease gradually, while the oxygen permeation flux of the dual-phase membrane is increase significantly.The Ce0.8Sm0.2O2-δ-Ca3Co2O6-δ membrane with the two phases weight ratio of 8∶2 exhibited excellent oxygen permeation performance, as 2.80×10-7 mol·cm-2·s-1 at 950 ℃, indicating it may be a promising candidate for oxygen separation.

Key words: Ce0.8Sm0.2O2-δ and Ca3Co2O6-δ powders were synthesized via coprecipitation and citrate complex methods, respectively, followed by sintering in air to achieve the dense Ce0.8Sm0.2O2-δ-Ca3Co2O6-δ dual-phase membrane.The phase composition and the microstructure of the samples were studied by X-ray diffraction patterns (XRD) and field emission scanning electron microscopy (FESEM), respectively.The study was carried out on elucidating of the influences of dual phase ratio on the thermal expansion coefficient, electronic conductivity and oxygen permeability of the dual-phase membrane.The experiment results indicate that the two phases exhibit good chemical stability, and the dense membrane is achieved after sintering at 1150 ℃ for 6 h.The membrane shows low thermal expansion coefficient, as 13.47×10-6 ~14.23×10-6 K-1, which is closed to that of the solid electrolyte.Increasing the ionic phase from 40wt; to 80wt;, the electronic conductivity is decrease gradually, while the oxygen permeation flux of the dual-phase membrane is increase significantly.The Ce0.8Sm0.2O2-δ-Ca3Co2O6-δ membrane with the two phases weight ratio of 8∶2 exhibited excellent oxygen permeation performance, as 2.80×10-7 mol·cm-2·s-1 at 950 ℃, indicating it may be a promising candidate for oxygen separation.