Effect of Mg Substitution on Room Temperature Dielectric and Magnetic Properties of Sr-Doped Bismuth Ferrite

Mg-co-substituted BiFeO3 was synthesized. We investigated the structure and multiferroic properties of Sr- and Mg-co-substituted bismuth ferrite. The purity and structural changes induced by Mg doping are confirmed by X-ray powder diffraction and Raman spectra. It was found that a small amount of Mg doping leads to dramatic enhancement in dielectric permittivity, along with an apparent improvement in ferromagnetism .Meanwhile, the co-substitution can effectively reduce the leakage current and increase the dielectric constant. The release of latent magnetization after Sr and Mg co-doping is stronger than the sum of two single dopings, indicating a nonlinear enhancement in Sr and Mg codoping. The ferromagnetism can be ascribed to the creation of unbalanced Fe3+ spins and relative long-range coupling mediated by the oxygen vacancies trapped localized electrons. Compared to the pristine bismuth ferrite, Bi0.95Sr0.05Fe0.9Mg0.1O3 exhibits more than fivefold improved magnetization with simultaneously improved electrical properties demonstrating the possibility of co-doped BiFeO3 for practical applications.