Enhancement of dielectric and electrical properties of NaNbO₃-modified BiFeO₃

Solid solutions of BiFeO₃ (BFO) and NaNbO₃ [i.e., (Bi_1−xNa_x) (Fe_1−xNb_x)O₃] for x = 0.1, 0.2, 0.3 were prepared by a mixed-oxide method. X-ray diffraction analysis confirms the formation of a single-phase system within a certain limit of x, and indicates that with increase in concentration of NaNbO₃ there is structural transformation of BFO from the rhombohedral to the tetragonal phase. The dielectric constant and loss-tangent of samples increase with rise in temperature. It is found that with increase of concentration of NaNbO₃ in the solid solution, tangent loss of BFO is greatly reduced that can be useful for some industrial applications. The appearance of hysteresis loops of the samples at room temperature confirms the ferroelectric properties of the materials. As the electrical conductivity of the above system increases with rise in temperature, it follows the Arrhenius relation. The frequency and temperature dependence of conductivity of the above system obeys Joncher’s universal power law. Some voltage is induced with the application of magnetic field confirming the existence of multiferroics properties in the materials. Leakage current reduces with increase in content of NaNbO₃ in the solid-solutions.