Role of Bi-excess on structural, electrical, optical, and magnetic properties BiFeO3 nanoparticles

The influence of Bi content on structural, optical, and multiferroic properties of BiFeO3 has been studied. The nanoparticles of BiFeO3 with different Bi content such as Bi0.00FeO3, Bi0.03FeO3, Bi0.05FeO3, Bi0.07FeO3, and Bi0.10FeO3 have been prepared using the nitric acid-assisted sol–gel method. The structural analysis of XRD patterns via Rietveld refinement revealed rhombohedral structure with R3c phase along with the minor secondary phase of Bi2Fe4O9. The crystallite size calculated using Scherrer’s formula was found to be in the range 56 nm ~ 41 nm. The lattice parameters and density were found in the range 8.78–8.81 A and 6.10–6.13 g/cm3, respectively. The highest value of maximum polarization and remnant polarization were found to be 1.15 μC/cm2 and 0.90 μC/cm2, respectively, for Bi0.05FeO3 nanoparticles. The Bi0.05FeO3 nanoparticles also showed a high dielectric constant with a smaller dielectric loss. The grain and grain boundaries have shown excellent electrical behavior as investigated via impedance, Modulus, and ac conductivity. The UV–Vis spectroscopy demonstrated that the Bi0.05FeO3 nanoparticles show the maximum bandgap of ~ 1.96 eV. The dc magnetization results infer the weak ferromagnetic behavior of the Bi-excess—BiFeO3 nanoparticles and indicate a maximum saturation magnetization of 0.24 emu/g for Bi0.05FeO3 nanoparticles.