Giant dielectric response and enhanced thermal stability of multiferroic BiFeO3

A wet chemical synthesis technique for large-scale fabrication of multiferroic bismuth ferrite (BiFeO3) nanoparticles under ambient pressure is reported. The process employs bismuth nitride and potassium hexacyanoferrate as raw materials and involves easy control and simple operation steps. The single crystalline nature of BiFeO3 was confirmed by X-ray diffraction (XRD) and selected area electron diffraction pattern. This synthesis technique can be extended to many other material systems and it provides a general, simple and convenient route for large-scale fabrication of nanocomplex oxides. Our results revealed that the synthesized BiFeO3 ceramics exhibited giant dielectric constant (>104) and two dielectric relaxations. A Debye-like relaxation was found at relatively low temperature with activation energy of 0.25 eV, which was assigned to the carrier hopping process between Fe2+ and Fe3+ sites in BiFeO3. The grain boundary effect contributed to the relative high temperature dielectric relaxation.