A Study on Fine-Tuning the Optical Energy Band Gap and Various Optical Parameters with the Impact of Gadolinium Composition in NGFO Ferrite Nanoparticles

Abstract

In the present work, gadolinium-doped nickel ferrite nanoparticles with the chemical composition NiFe2−xGdxO4 (X = 0.00, 0.05, 0.10, 0.15, 0.20, and 0.25) have been prepared by the sol-gel auto-combustion method and calcinated at 700 ∘C. The spinel ferrite phase formation was confirmed with the XRD graphs. In all the samples, the typical absorbance peak was observed in between 250–300 nm. Tauc plots were used to calculate the optical energy band gap, found in the range of 4.033–4.144 eV, and it was also calculated using x-ray density to be in the range of 3.690–4.300 eV. Both of them were observed in good agreement with each other, and we conclude that the Gd composition could finely tune the optical energy band gap. The impact of Gd composition was clearly observed on optical parameters. The refractive index, reflectivity, absorption coefficient, optical dielectric constant, and dielectric susceptibility have shown the increasing tendency from 2.1140 to 2.2325, 12.80 to 14.53%, 5.4380 to 6.3032 cm−1, 3.4690 to 3.9840 and 0.2760 to 0.3170, respectively, whereas the transmission coefficient decreased from 0.7730 to 0.7461.