A comparative study on physico-chemical, optical, magnetic and ferroelectric properties of undoped BiFeO3 and Ni-doped BiFeO3 nanoparticles

Abstract

Undoped BiFeO3 and Ni-doped BiFeO3 nanostructures were synthesised via colloidal gel, followed by a combustion reaction at a processing temperature of 500 °C, for testing their multiferrioic properties. Powder X-ray diffraction studies reveal the rhombohedral perovskite crystal structure for the synthesized pure BiFeO3, whereas Ni-doped BiFeO3 sample shows the formation of the rhombohedral perovskite structure along with the heterogeneous phase contains Fe2O3 and Bi2Fe4O9. The energy band gap (Eg) of Ni-doped BiFeO3 was found to be reduced (1.87 eV) compared to the Eg value (2.02 eV) of undoped BiFeO3, as confirmed by the Tauc plot. The synthesized compounds were tested for their vibrational bands by FT-IR analysis, and strong absorption bands were found at 555 cm−1, which attribute the vibration bonds of Bi-O and Fe-O. The aggregated particles with irregular morphology appeared in the TEM images of the undoped BiFeO3 and the presence of Ni-doped incorporation of BiFeO3. The ferromagnetic and ferroelectric behaviour of the synthesized undoped and Ni-doped BiFeO3materials was noticed in the magnetization vs. magnetic field (M−H) loops and polarization–electric field (P-E) at room temperature. The areas of the hysteresis loop, coercive force, magnetic saturation, saturation polarization, remanent magnetization, and polarization of Ni-doped BiFeO3 were decreased compared to undoped BiFeO3. The investigated Ni-doped BiFeO3 results were elucidated to assess the soft magnetic nature of device applications.