Ion and electron conduction in SrFe1−xScxO3−δ

The oxygen ion and electron transport in SrFe1−xScxO3−δ (x = 0.1–0.3) system at 700–950 °C were studied analyzing the total conductivity dependencies on the oxygen partial pressure, pO2. The conductivity measurements were performed both under reducing conditions (10− 19 ≤ pO2 ≤ 10− 8 atm) comprising the electron-hole equilibrium point, and in oxidizing atmospheres (10− 5 ≤ pO2 ≤ 0.5 atm) which are characterized by extensive variations of the oxygen content studied by coulometric titration technique. The incorporation of 10% Sc3+ cations into the iron sublattice suppresses transition of the cubic perovskite phase into vacancy-ordered brownmillerite, thus improving ion conduction at temperatures below 850 °C. When scandium content increases, the ion conductivity becomes considerably lower. The hole mobility is thermally-activated and varies in the range of 0.001 to 0.05 cm2 V− 1 s− 1, increasing with oxygen concentration and decreasing on Sc doping.