Electronic properties of SrFeO2 doped by Ca and Ba: A first-principles study

Abstract

ABO2-type perovskite materials have been wide applied in solid oxide fuel cells and gas sensors. SrFeO2 with P4/mmm structure exhibiting an unparalleled FeO4 square-planar coordination structure. We have investigated the Sr-site substitution effect on the electronic conductivity of the perovskite-type structure of (Sr1−xCax)FeO2 and (Sr1−xBax)FeO2 (x=0, 0.25, 0.5, 0.75) by using first-principle calculations. Six kinds of doping form have been considered for the Ca-site and Ba-site, respectively. The different doping concentration and position lead to change in crystal structure and electronic properties. When x=0.5, α and β doping structures display Pmmm symmetry, while γ and δ doping structures show P4/mmm symmetry. The band structure and density of states reveal that different doping concentration and position can make the electronic conductivity change from semiconductor to semi-metallic. When x=0.25, 0.75, 0.5 for γ and δ doping, the doped system were semi-metallic properties. Whereas, when x=0.5 for α and β doping, the doped system were semiconductor properties. Further, doping can lead to an increase of the magnetic moments. It is worth noting that the Ca-doped system has higher growth in the magnetic moments compare with the Ba-doped system. This work provides a new route for the potential application in electrochemistry devices.