Abstract:

SrFe(Cu,Ti)OO_3-δ mixed conducting membrane materials were synthesized by citric acid complexing method. The stabilities of the materials were studied by means of XRD, O₂-TPD, H₂-TPR and SEM. It was found that phase decomposition occurred in SrFe_0.7Cu_0.3O_3-δ under a low oxygen partial pressure and a minor phase SrCuO₂ was formed. The addition of Ti⁴⁺ greatly enhanced the structure stability of the material, and SrFe_0.6Cu_0.3Ti_0.1O_3-δ maintained singlephased perovskite structure. H₂-TPR and O₂-TPD results showed that the addition of Ti⁴⁺ increased the initial oxygen desorption temperature of the material, and the reduction temperature of the other metal ions. Slight phase decomposition was found on the Heside surface of SrFe_0.6Cu_0.3Ti_0.1O_3-δ membrane after oxygen permeating test and fresh small grains congregated at the boundary of the initial grains. SrFe_0.6Cu_0.3Ti_0.1O_3-δ  exhibits a high stability during 66 h oxygen permeating process.

Key words: oxygen permeation,mixed conductor,perovskite,phase stability