The effect of Ni substitution on magnetic, dielectric and magnetoelectric properties in BiFe1−xNixO3 system

Multiferroic nanoceramics BiFe1−xNixO3 (where x=0, 0.15, 0.20, and 0.25) were prepared by the sol–gel method. XRD analysis of samples calcined at a low temperature of 400 °C for 2 h shows the formation of a single phase perovskite rhombohedral structure. Average particle size was observed to be ∼50 nm by TEM measurement. Magnetization was found to increase with increase in the concentration of Ni. Dielectric constant and dielectric loss were measured up to 1 MHz frequency. Variation of dielectric constant with temperature shows a peak at ∼395 °C (Neel temperature) for x=0.15 and the peak shifts towards lower temperature at a higher concentration of Ni with diffused type of phase transition. Magnetocapacitance was found to decrease with magnetic field. For BiFe1−xNixO3 (with x=0.15, 0.20, 0.25) nanoceramics, the fractional change of the magnetic field induced a change in the dielectric constant, which may well be approximated by Δε/ε=γM2, (where γ (magnetoelectric interaction ) is small and negative). A linear fit gave the value of γ of ∼−2.14×10−3, −2.11×10−3, and −2.09×10−3 for BiFe1−xNixO3 nanoceramics, with x=0.15, 0.20, and 0.25, respectively.