BaxSr1-xCoyFe1-yO3-δ (BSCF) mixed ionic-electronic conducting (MIEC) materials for oxygen separation membrane and SOFC applications: Insights into processing, stability, and functional properties

Cubic perovskite BaxSr1-xCoyFe1-yO3-δ (BSCF), with x = 0.5 and y = 0.8, is one of the oxygen permeable mixed ionic-electronic conducting (MIEC) membrane materials having the highest oxygen permeation flux reported. The material has potential for high-temperature electrochemical applications such as oxygen separation membrane and cathode for Solid Oxide Fuel Cells (SOFCs). The material has been highly studied, focusing on the oxygen transport properties, thermochemical expansion, mechanical properties, high temperature creep behavior, chemical sealing, etc. Therefore, a review article that consolidates the existing knowledge is necessary. The available review articles have focused on mechanical properties and applications as cathode for intermediate temperature (IT) SOFCs. Hence, this review article has covered additional information about crystal structure and oxygen non-stoichiometry of BSCF, material synthesis, membrane fabrication, thermomechanical stability, phase stability with respect to temperature and oxygen partial pressure, mechanical properties as well as the performance analysis in terms of oxygen permeation flux and failure analysis. It also emphasizes the potential of BSCF as MIEC membrane material. The content is equally helpful for researchers who are newcomers to the field and have the intention to provide a basic understanding of MIEC membrane materials.