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 degrees C for 2 h shows the formation of a single phase perovskite rhombohedral structure. Average particle size was observed to be similar to 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 similar to 395 degrees 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 BiFe(1-x)NixO(3) (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 Delta epsilon/epsilon=gamma M-2, (where gamma (magnetoelectric interaction) is small and negative). A linear fit gave the value of gamma of similar to-2.14 x 10(-3), -2.11 x 10(-3), and -2.09 x 10(-3) for BiFe1-xNixO3 nanoceramics, with x=0.15, 0.20, and 0.25, respectively. (C) 2010 Elsevier B.V. All rights reserved.