Enhanced magnetoelectric properties of BiFeO3 on formation of BiFeO3/SrFe12O19 nanocomposites.

Nanocomposites (NCs) comprising (1-x) BiFeO3 (BFO) and x SrFe12O19 (SRF) (x=0.1, 0.2, 0.3, and 0.4) have been prepared by a sol-gel route. Presence of pure phases of both BiFeO3 (BFO) and SrFe12O19 (SRF) in the NCs for x=0.3 and 0.4 has been confirmed by Rietveld analysis of XRD data though a minor impurity phase is observed in the case of x=0.1 and 0.2 NCs. Transmission electron micrographs of the NCs show that particles are mostly spherical with average size of 30 nm. M-H measurements at 300 and 10K indicate predominantly ferrimagnetic behavior of all the NCs with an increasing trend of saturation magnetization values with increasing content of SRF. Dielectric constant (εr) of the NCs at room temperature shows a dispersive behavior with frequency and attains a constant value at higher frequency. εr - T measurements reveal an increasing trend of dielectric constant of the NCs with increasing temperature and show an anomaly around the antiferromagnetic transition temperature of BFO, which indicates magnetoelectric coupling in the NCs. The variation of capacitance in the presence of magnetic field confirms the enhancement of magnetoelectric effect in the NCs. 57Fe Mössbauer spectroscopy results indicate the presence of only Fe3+ ions in usual crystallographic sites of BFO and SRF. [ABSTRACT FROM AUTHOR]