Synthesis and characterization of gallium-based perovskitetype dense membrane with oxygen semipermeability

La_0.15Sr_0.85Ga_0.3Fe_0.7O_3-δ (LSGFO) and La_0.15Sr_0.85Co_0.3Fe_0.7O_3-δ (LSCFO) mixed oxygenion and electron conducting oxides were synthesized by using a combined EDTA and citrate complexing method, and the corresponding dense membranes were fabricated. The properties of the oxide powders and membranes were characterized with combined SEM, XRD, H₂-TPR, O₂-TPD techniques, mechanical strength and oxygen permeation measurement. The results showed that LSGFO had much higher thermochemical stability than LSCFO due to the higher valence stability of Ga³⁺. After the temperature-programmed reduction by 5% H₂ in Ar from 20°C to 1020°C, the basic perovskite structure of LSGFO was successfully preserved. LSGFO also favors the oxygen vacancy formation better than LSCFO. Oxygen permeation measurement demonstrated that LSGFO had higher oxygen permeation flux than LSCFO, but they had similar activation energy for oxygen transportation, with a value of 110 and 117 kJ · mol^-1, respectively. The difference in oxygen permeation fluxes was correlated with the difference in oxygen vacancy concentrations for the two materials.