Structural crystallinity and optical behavior of MgFe2O4 ferrite nanoparticles prepared by sol–gel method

Abstract

Magnesium ferrite (MgFe2O4) nanoparticles have attracted significant interest due to their excellent magnetic, electrical, and optical properties, which make them suitable for applications in magnetic storage devices, microwave absorbers, catalysts, sensors, and optoelectronic systems. In the present study, nanocrystalline MgFe2O4 ferrites were successfully synthesized using a sol–gel method employing magnesium nitrate and ferric nitrate as precursor materials and citric acid as a chelating agent. The effect of citric acid concentration on the structural and optical properties of the synthesized nanoparticles was systematically investigated. The structural characteristics were analyzed using X-ray diffraction, which confirmed the formation of a single-phase cubic spinel structure with high phase purity. An increase in the degree of crystallinity from 70 to 93% was observed with variation in citric acid concentration, indicating improved crystal growth and structural ordering. The crystallite size was estimated using both the Debye–Scherrer equation and Williamson–Hall (W–H) analysis. The calculated crystallite sizes ranged from ~ 2 to 29 nm, confirming the nanocrystalline nature of the prepared samples. W–H analysis further revealed the presence of lattice microstrain, which contributes to the structural evolution of the ferrite nanoparticles. The optical properties were investigated using UV–Visible spectroscopy. The absorption spectra exhibited strong absorption in the ultraviolet region, demonstrating the light-responsive nature of the synthesized materials. The optical band gap energy, determined using Tauc plot analysis, varied between 2.03 and 2.18 eV. The observed variation in band gap is attributed to changes in crystallite size and microstructural characteristics, with smaller crystallites exhibiting enhanced quantum confinement effects. The results demonstrate that the sol–gel technique is an effective route for producing high-quality MgFe2O4 nanoparticles with tunable structural and optical properties. The combination of nanoscale crystallite size, high crystallinity, and adjustable band gap makes these materials promising candidates for advanced magnetic, catalytic, and optoelectronic applications.