Oxygen and electron transport in Ce0.1Sr0.9FeO3-δ

Ce0.1Sr0.9FeO3-delta was synthesized via a solid-state reaction in air and confirmed to be single-phase with the cubic perovskite structure (SG Pm (3) over barm). The oxygen content variation in the oxide was measured by a thermogravimetric technique in air from room temperature to 950 degrees C, and by a coulometric titration at 950 degrees C in the range of oxygen partial pressure (p(O2)) from 10(-15) atm to 0.5 atm. Electrical conductivity (sigma) was measured by a four-probe dc technique in the p(O2) interval of 10(-18)-0.5 atm at 750-950 degrees C. Partial contributions to total conductivity from oxygen ions, electrons, and holes were separated, based on their different dependence on oxygen partial pressure. The obtained data were used to estimate oxygen flux density (j(O2)) through the oxide membrane. The obtained characteristics were compared with those of La0.5Sr0.5FeO3-delta as the most promising ferrite for an oxygen membrane material. While oxygen-ion and hole conductivity were higher in Ce0.1Sr0.9FeO3-delta, Ce0.1Sr0.9FeO3-delta had higher electron conductivity. Though oxygen flux density 8 ml.cm( -2) min(-1), calculated for a membrane of Ce0.1Sr0.9FeO3-delta under partial methane oxidation conditions was similar to 25% lower than that for Ce0.1Sr0.9FeO3-delta it characterized this oxide as a promising membrane material.