Effects of Ni Substitution on the Electronic Structure and Magnetic Properties of Perovskite SrFeO3

Abstract

Effects of nickel substitution on the physical properties of perovskite SrFe1−xNixO3 (x = 0, 0.25, 0.50, 0.75 and 1) are investigated by density functional theory (DFT) using local density approximation (LDA), generalized gradient approximation (GGA) and GGA supplemented with a localization correction (GGA + U). It is found that the GGA + U results are the much consistent with experiments. The lattice constants decreases with the increase of Ni substitution and are found to be stable for all concentrations. The electron charge densities reveal that the bond between Sr-O is ionic; the Fe/Ni-O bond is covalent and the Ni-Fe bond is metallic. Electronic band structure comparisons and electrical properties reveal the metallic nature of samples. DFT as well as post-DFT calculations confirm that the magnetic interactions are anti-ferromagnetic for SrFeO3, while they are ferromagnetic for all Ni concentrations. The mechanism is elucidated by exchange interactions with magnetic transitions above room temperature. Due to the metallic nature and good electrical conductivity of these materials, it is expected that they could be used as electrode materials in fuel cells.