The effects of Fe-substitution on the crystal structure and oxygen permeability of PrBaCo2O5+δ

• Effect of Fe substitution for Co on the structure and performance of PBCO membranes.
• The structural change from orthorhombic to cubic is observed upon Fe-substitution.
• Fe-substitution decreases the oxygen permeation rate and oxygen ion conductivity.
• Insignificant effect of the crystal structure on the oxygen permeation of PBCF.

A series of double layered perovskites, PrBaCo2−xFexO5+δ (x=0, 0.2, 0.5, 1, 1.5, and 2), are successfully prepared employing a solid state reaction. The effects of Fe substitution on the crystal structure and oxygen transport properties of PrBaCo2O5+δ were investigated by X-ray diffraction and oxygen permeation experiments. X-ray diffraction patterns confirm that PrBaCo2O5+δ, PrBaCo1.8Fe0.2O5+δ, PrBaCo1.5Fe0.5O5+δ, and PrBaFe2O5+δ exhibit an orthorhombic perovskite structure, while PrBaCoFeO5+δ, and PrBaCo0.5Fe1.5O5+δ crystallize in a cubic perovskite. The oxygen permeation flux of PrBaCo2−xFexO5+δ is found to decrease with increasing Fe content. Among the compositions, PrBaCo2O5+δ shows the highest oxygen permeation flux of 1.89×10−7 mol cm−2 s−1 at 900 °C under an air/helium atmosphere.