The oxygen permeation characteristics of Bi1 − xSrxFeO3 mixed ionic and electronic conducting ceramics

The perovskite oxides in the system Bi1 − xSrxFeO3 − δ (x = 0.05, 0.15, 0.3, 0.6, and 0.8) were characterized in the intermediate temperature range (650 to 800 °C) by oxygen permeation and electrical conductivity measurements. The samples exhibited a single phase perovskite structure with a decreasing lattice constant with increasing Sr concentration and a structural change from rhombohedral to cubic at x ≥ 0.3. Mixed conductivity was confirmed in all samples with maximum flux levels on the order of 0.11 μmol/cm2 s at 800 °C for the x = 0.8 composition. Materials studied displayed p-type conductivity over the oxygen partial pressure range present in permeation measurements (0.21 to 10− 6 atm). A local maximum of oxygen flux and ionic conductivity was found near x = 0.3.