Fabrication and characterization of cubic Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ perovskite for a novel "star-shaped" oxygen membrane with a developed surface

Highlights: • Innovative fabrication technology was elaborated for BSCF membrane with developed surface. • The tool for membranes forming with developed surface was designed and executed. • As a result of forming process, membranes with "star shape" design were obtained. • Concentration of oxygen vacancies in BSCF increases considerably with temperature. • The small polaron hopping depends on the oxygen stoichiometry deviation. - Abstract: Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF), a material which can be used for the fabrication of oxygen membranes with developed surfaces, was synthesized by a solid state method. The most important material properties which have influence on the oxygen membrane usability were investigated. An innovative fabrication technology was developed for the preparation of oxygen membranes with developed surfaces by using vacuum extrusion. The tool to form membranes on a vacuum worm press was designed and executed. These allowed the formation, for the first time, of a novel "star shaped" architecture for an oxygen membrane, enabling the use of a higher effective surface for oxygen production. Comprehensive studies on structural and microstructural properties, apparent density and porosity, water absorbability, oxygen stoichiometry, thermal expansion and electrical conductivity of the BSCF membrane were performed. The results obtained demonstrated the potential application of "star-shaped" oxygen membranes in oxy-fuel combustion technology.