Determination of the crystal structure and charge density of (Ba0.5Sr0.5)(Co0.8Fe0.2)O2.33 by Rietveld refinement and maximum entropy method analysis

The crystal structure and charge density of (Ba0.5Sr0.5)(Co0.8Fe0.2)O2.33, a promising cathode material for solid oxide fuel cells with lower operating temperatures, were investigated by the Rietveld refinement method and the maximum entropy method (MEM) using neutron and synchrotron X-ray diffraction data. The crystal structure of (Ba0.5Sr0.5)(Co0.8Fe0.2)O2.33 was refined by using the orthorhombic Pnma   space group and the split atom model to cation sites. The occupancy of O1 (4c)(4c) and O2 (8d)(8d) sites are 0.59 and 0.87, respectively. From the MEM analysis, we found that (Ba0.5Sr0.5)(Co0.8Fe0.2)O2.33 possessed both covalent and ionic bonds.