Oxygen non-stoichiometry and mixed conductivity of Ti -doped BaCo0.4Fe0.4Y0.2O3-δ perovskite

Abstract

The mixed electronic-ionic conducting (MIEC) perovskite materials are promising as a cathode of solid oxide fuel cells (SOFCs). According to recent reports, BaCo0.4Fe0.4Zr0.2O3-δ (BCFZ) and its doped compounds exhibit potentiality under the SOFCs operating conditions at intermediate-low temperatures. The structural, oxygen non-stoichiometry, electrical conductivity, and oxygen permeability properties of Ti-doped BaCo0.4Fe0.4Y0.2O3-δ was characterized and then compared with those of BaCo0.4Fe0.4Y0.2O3-δ or Mg-doped BaCo0.4Fe0.4Y0.2O3-δ. The cubic symmetry with space group Pm-3m crystallizes in all the prepared samples. The Ti-doped sample displayed the highest total electrical conductivity of 3.19 S cm−1 at 800 °C, which is higher than the conductivity of the Mg-doped sample (2.52 S cm−1). The oxygen permeability of Ti and Mg-doped samples are 0.46 and 0.48 μmol cm−2 s−1 at 800 °C, respectively. The obtained MIEC (total electronic and oxygen ion conductivities) is higher compared to the BaCo0.4Fe0.4Y0.2O3-δ (total electrical conductivity of 2.9 S cm−1 and oxygen permeability of 0.26 μmol cm−2 s−1) potential cathode within the intermediate temperature-based SOFCs. Thus, this work proposes that Ti-doped perovskite could be a new cathode candidate for SOFCs, concerning structural stability and high mixed electronic-ionic conductivity.