Effect of oxygen annealing on magnetic, electric and magnetodielectric properties of Ba-doped BiFeO3

We investigate the effect of oxygen annealing on magnetic, electric and magnetodielectric properties of Ba-doped BiFeO3, Bi0.75Ba0.25FeO3 (BBFO) bulk. Magnetization, resistivity, polarization and magnetodielectric measurements reveal that as-grown BBFO shows weak ferromagnetism, leaky dielectric behavior with activation energy of 0.40 eV and 0.06% change of dielectric constant at 60 kOe. However, oxygen-annealed BBFO at 850 °C shows antiferromagnetism, leaky dielectric behavior with activation energy of 0.73 eV and 0.04% change of dielectric constant at 60 kOe. These differences are discussed by the formation of Fe3+ valence with oxygen vacancy in as-grown BBFO, and the formation of mixed Fe3+ and Fe4+ valences without oxygen vacancy for oxygen-annealed BBFO.