Enhanced structural, optical, dielectric, and electrical properties of CoFe2O4 nanostructures: Effect of variation of citric acid concentration

In the current work, the authors report on the facile synthesis of CoFe2O4 (CFO) nanoparticles (NPs) with different citric acid (CA) concentrations and at a constant temperature. The synthesized nanostructures were investigated for structural, vibrational, morphological, opto-dielectric, and electrical characteristics. X-ray diffraction analysis confirmed their cubic structural phase, while allowing other microstructural parameters to be investigated. The crystallite size based Scherrer and W-H plot methods ranged from 23 to 30 nm and 21-30 nm, respectively, and declined with the increase in CA concentration. The vibrational analysis confirmed the pure phase of CFO at all CA concentrations. Diffused reflectance spectra were measured to determine the bandgap energy of CFO NPs, which increased from 2.10 to 2.35 eV as the CA content increased, whereas CFO NP grain size declined, as confirmed by SEM measurements. EDX analysis and SEM e-mapping study further revealed that the CFO was synthesized with proper composition. According to the dielectric and electrical studies (performed up to 10 MHz), the dielectric constant ranged from 130 to 160, and the highest value was obtained for CFO containing 0.25 g of CA. Finally, the frequency exponent indicates the CBH model of carrier charge conduction mechanism in the CFO samples. Therefore, the low particle size, wide bandgap, and high dielectric constant values of the synthesized CFO NPs make them suitable candidates for optoelectronic applications.