BiFeO3-based Ceramics Research Articles

Improved leakage current and ferromagnetic properties in magnetic field annealed BiFeO3-based ceramics

Abstract Single-phase Bi0.85La0.15FeO3 ceramics were synthesized under various magnetic fields (Ha=0 T, 3 T, 5 T). Substantially reduced leakage current and hence modified ferroelectric (FE) properties were obtained with magnetic field annealing (MA). The largest magnetization and lowest leakage current with large FE polarization (Pr∼33 μC/cm2) were found in the sample annealed with Ha=3 T. Great changes were also observed in the Raman spectra. All the observed features originate mainly from the different FE domain wall structures induced by MA. These results demonstrate that MA is an effective way to tune the multiferroic and magnetoelectric properties in BiFeO3-based materials.

Synthesis and properties of perovskite BiFeO3-K0.5Na0.5NbO3 ceramics by solid-state reaction

Rhombohedrally distorted perovskite BiFeO3–K0.5Na0.5NbO3 ceramics with ferroelectricity and ferromagnetism were synthesized by solid-state reaction. The effect of K0.5Na0.5NbO3 content on the crystal structure, electrical and magnetic properties of a BiFeO3–K0.5Na0.5NbO3 system was examined with a view to achieving multiferroic BiFeO3-based ceramics. Perovskite BiFeO3–K0.5Na0.5NbO3 single phase was obtained by formation of solid solution with K0.5Na0.5NbO3, whereas pure BiFeO3 ceramics contained a small amount of a second phase, such as Bi36Fe2O57. The crystallographic symmetry of BiFeO3–K0.5Na0.5NbO3 changed from rhombohedral to cubic when the content of K0.5Na0.5NbO3 exceeded 15 mol %. The rhombohedrally distorted BiFeO3–K0.5Na0.5NbO3 showed a high Curie temperature (>770°C) and weak ferromagnetism at room temperature. Dielectric properties of the resultant ceramics were improved by controlling the amount of Mn doping to facilitate ferroelectric measurements.