Dependence of dielectric behavior in BiFeO3 ceramics on intrinsic defects

Multiferroic BiFeO3 (bismuth ferrite, BFO) ceramics were sintered using a rapid heating and quenching technique in an atmosphere of argon or oxygen. The resulting ceramics were phase pure with the space group R3c. BFO ceramics sintered under an argon atmosphere contained more oxygen vacancies and Fe2+ ions compared with those sintered under an oxygen atmosphere, which resulted in high dielectric loss and large dielectric dispersion. It confirms that the unavoidable Fe2+ ions may play a fundamental role in these special materials, such as in the evaporation of the Bi component and valence change of the Fe component. This work also discusses the dielectric response mechanism in BFO ceramics