Origin of magnetic and dielectric response in single phase nano crystalline BiFeO₃

Stoichiometric and single phase synthesis of BiFeO₃ is critical both in its particle industrial applications as well as in understanding the origin of its attractive dielectric and magnetic properties. In this study, BiFeO₃ has been obtained at temperatures as low as 400 °C. Zero Fe⁺²/Fe⁺³ ratio, and absence of bismuth and oxygen non-stoichiometry have been probed by ⁵⁷Fe Mössbauer spectroscopy. The appearance of different magnetic phases in ⁵⁷Fe Mössbauer spectrum, MH hysteresis curve and exchange bias effect have been conferred on the basis of magneto-crystalline anisotropy and particle size distribution. Dependence of the dielectric response on the applied electric field reveals that the colossal dielectric response in BiFeO₃ is dominated by extrinsic effects at grain-grain interface. (paper)