X-ray photoelectron spectra, conductivity, and oxygen permeation characteristics of (Ba0.5Sr0.5)(Fe1-xCex)O3-6 (x=0-1.0) perovskites

X-ray photoelectron spectra, conductivity and oxygen permeability of perovskite-type (Ba0.5Sr0.5)(Fe1-xCex)O3-6 (x = 0-1.0) oxides are reported. The concentration of Fe4+ and Ce4+ decreases with 'x' via Fe4+(/Ce4+) -> Fe3+(/ Ce3+) conversions which, in turn, oxygen deficiency (6) increases. The spectrum of oxygen (O1s) is attributed to stoichiometric, adsorbed and chemically adsorbed species at-531.5, 532.8 and 534.4 eV, respectively (say, for x = 0.30). The oxygen permeability (Jo2) of disc membrane lies in the range of-1.474-2.204 ml/cm2-min at 950 degrees C (input feed air-400 ml/min, carrier argon gas-40 ml/min) for x = 0-1.0. Maximum Jo2 is observed for x = 0 (cubic phase) in comparison to other compositions viz., x = 0.10-0.60 (cubic + orthorhombic phases) and x = 0.80-1.0 (orthorhombic phase). The electrical conductivity increases until a characteristic temperature, then slowly decreases with increasing cerium concentration (x). The structural transformation of (Ba0.5Sr0.5)(Fe1-xCex) O3-6 plays an important role in determining the conductivity (sigma) and oxygen permeation. These analyses make material useful for applications dealing with oxygen separations.

Automated summary

X-ray photoelectron spectra, conductivity, and oxygen permeability of perovskite-type (Ba0.5Sr0.5)(Fe1-xCex)O3-6 (x = 0-1.0) oxides were investigated. The concentration of Fe4+ and Ce4+ decreases with increasing x, leading to an increase in oxygen deficiency. The oxygen permeability of the membranes exhibits the maximum for x = 0 (cubic phase) and decreases for other compositions. The conductivity increases initially and then decreases with increasing cerium concentration.