Effect of synthesis route on the multiferroic properties of BiFeO3: A comparative study between solid state and sol-gel methods

Polycrystalline BiFeO3 (BFO) powder was prepared through optimized solid state (SS) and sol-gel (SG) reaction methods. The effect of preparation routes on the crystal purity and multiferroic properties of the BFO was investigated. Sol-gel synthesis results almost a single-phase material at relatively lower temperatures while the solid-state method results into BFO with a small amount of Bi2Fe4O9 secondary phase. The grain size of SG processed sample reduces to half the size of the one that is prepared by SS. Elemental analysis shows a stoichiometric Bi:Fe content for SG samples by restricting the Bi loss. In comparison with the SS samples, dielectric constant of SG samples exhibit higher values with Maxwell-Wagner type dielectric dispersion. A cusp at 50 K was seen in M-T curves for SS samples, for which no frequency dependence was observed in a.c susceptibility measurements ruling out the earlier predictions of spin glass nature in this system. M - H loops show a typical antiferromagnetic nature at 300 K while a weak ferromagnetic behavior is found at 10 K. A slight increase in H-C and M-r was observed for SG samples over SS. The improved properties of SG processed BFO makes it more promising for applications. (C) 2015 Elsevier B.V. All rights reserved.