Effects of Nb-doping on electric and magnetic properties in multi-ferroic BiFeO3 ceramics

Nb-doped BiFeO3 polycrystalline ceramics were synthesized by a solid-state reaction and their dielectric and magnetic properties were investigated. Nb-doping increased the electrical resistivity of BiFeO3 by approximately six orders of magnitude, which allowed the dielectric properties to be determined at room temperature. The room temperature dielectric constant was ∼100 and the electric hyteresis loops were not really saturated in the Nb-doped BiFeO3 ceramics. Nb-doped BiFeO3 also showed a ferromagnetic-like behavior with Mr=0.015 emu/g and Hc=500 Oe, which is similar to the solid solution system of BiFeO3 and BaTiO3. The coupling between electric dipole and magnetic dipole was estimated by determining the changes of the dielectric constant with the external magnetic field up to 90 kOe.