Structural dependence of magnetic, luminescence and band gap of Li-Mg ferrite nanomaterials

In this study, Mg_1-0.5xLi_xFe₂O₄ (x = 0.1, 0.2, and 0.3) were synthesized using the citrate precursor sol-gel method. The study also focuses on the consequence of lithium substitution on their structural, optical, and magnetic characteristics using XRD, FTIR, EDX, FESEM, PL spectroscopy, VSM, and UV-visible spectroscopy. Li-substituted ferrite with x = 0.1, 0.2, and 0.3, respectively, had an average crystallite size of 43.83 nm, 41.11 nm, and 38.39 nm, according to an analysis of the XRD data. Li-substitution in magnesium ferrite generated lattice strain, which in turn caused crystal defects. Using FTIR, metal oxide bonds between 415 and 572 cm⁻¹ were investigated. The rise in Li concentration resulted in a notable reduction in agglomerated grain size, from 150 to 73 nm, according to FESEM investigations. Grain boundary defects existed in the produced ferrites, as evidenced by the noticeable grain boundaries in the FESEM micrographs. Li-substitution in the prepared ferrite resulted in a substantial increase in the band gap from 2.35 to 2.41 eV and may have been caused by the reduction in crystallite size. The photoluminescence spectra, which showed a peak at 482 nm and emission wavelengths ranging from 417 to 571 nm, revealed crystallographic imperfections and oxygen vacancies. Magnetic measurements demonstrated a decrease in saturation magnetization from 37.54 emu/g to 18.58 emu/g, along with an increase in coercivity from 78.39 Oe to 115.66 Oe, indicating enhanced magnetic properties with lithium substitution. The study presents a novel composition of Li-substituted magnesium ferrites, whose defects driven structural and photoluminescence characteristics make them promising candidates for renewable energy applications such as hydroelectric cells. The possibility of use in hydroelectric cells opens new paths for further research in energy harvesting technologies.