Enhanced electrical conductivity and multiferroic property of cobalt-doped bismuth ferrite nanoparticles

Multiferroic pure and cobalt-doped bismuth ferrite nanoparticles were synthesized by sol–gel method. The X-ray diffraction study showed a distinct crystalline phase with rhombohedral R3c structure. Rietveld refinement confirmed the reduction of crystallite size from 68 to 45 nm in doped BFO. Transmission electron microscopy was performed to confirm the morphology and lattice constant of the pure and cobalt-doped bismuth ferrite nanoparticles. The results of lattice constant have also been compared with the XRD results. Dielectric properties such as resistance, reactance, impedance, and resistivity were significantly decreased in doped BFO to 7.5 MΩ, 14 MΩ, 17 MΩ, 3.7 MΩ-m, respectively, at 100 Hz with concurrent increased conductivity of 0.184 (S/m) × 10–3 at 10 MHz. The ferroelectric properties of pure and doped samples exhibited significantly enhanced maximum polarization and coercive field in doped BFO of 16 µC/cm2 and 6.2 kV/cm, respectively, at an applied field of 15 kV/cm. Ferromagnetic measurements of synthesized cobalt-doped BFO nanoparticles displayed a substantial improvement in saturation magnetization and coercive force of 7.07 emu/gm and 0.9 kOe, respectively. The important enhancement of magnetic properties with moderate value of coercive field of the cobalt-doped samples may have potential applications in spintronics and memory devices.