Role of Bi-excess on structural, electrical, optical, and magnetic properties BiFeO_3 nanoparticles

摘要

The influence of Bi content on structural, optical, and multiferroic properties of BiFeO_3 has been studied. The nanoparticles of BiFeO_3 with different Bi content such as Bi_(0.00)FeO_3, Bi_(0.03)FeO_3, Bi_(0.05)FeO_3, Bi_(0.07)FeO_3, and Bi_(0.10)FeO_3 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 Bi_2Fe_4O_9. 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/cm~3, respectively. The highest value of maximum polarization and remnant polarization were found to be 1.15 μC/cm~2 and 0.90 μC/cm~2, respectively, for Bi_(0.05)FeO_3 nanoparticles. The Bi_(0.05)FeO_3 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 Bi_(0.05)FeO_3 nanoparticles show the maximum bandgap of ～ 1.96 eV. The dc magnetization results infer the weak ferromagnetic behavior of the Bi-excess-BiFeO_3 nanoparticles and indicate a maximum saturation magnetization of 0.24 emu/g for Bi_(0.05)FeO_3 nanoparticles.