Tuning the electrical, structural, and electrochemical properties of Sm/Ni Co-doped BiFeO₃ nanostructures for supercapacitor applications

Nanocrystalline powder samples of sol-gel synthesized Bi1-xSmxFe1-xNixO3 (x = 0.00, 0.03, 0.06, 0.09) perovskite ferrites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), UV-Vis, cyclic voltammetry (CV), dielectric analysis, and IV. XRD study of BiFeO₃ and its doped variants reveals rhombohedral structures characterized by the space group R3c. Peaks indicate effective doping, with an average crystallite size of 58.95 nm. SEM micrographs of BFO and Ni-Sm doped materials exhibit increased aggregation and uneven shapes as the concentration of (Ni, Sm) ions rises, resulting in a reduction of oxygen vacancies. FTIR analysis reveals octahedral and tetrahedral absorption bands, validating the production of FeO₆ and perovskite structures. UV-Visible Spectroscopy indicates a reduced optical band gap ranging from 3.99 to 3.56 eV with increasing replacement of Sm and Ni, making it suitable for solar cell applications. CV electrochemical examination of pure and doped nanoparticles for supercapacitors demonstrates increased specific capacitance (217.50–270.10 F/g) and improved redox peaks, signifying greater electrochemical performance. Conductivity and dielectric tests of product samples indicate improved electrical characteristics resulting from Ni and Sm replacement. Conductivity varies from 1.65×10⁻⁸ to 4.95×10⁻⁸ ohm⁻1 cm⁻1, whereas dielectric constant and loss values decrease as frequency increases. The composition Bi0.91Sm0.09Fe0.91Ni0.09O3 has potential for electrical device applications owing to enhanced conductivity and dielectric properties.