Er⁺-Doped Magnesium Ferrite Nanoparticles' Structural, Optical, And Thermal Characteristics Produced Using the Sol-Gel Combustion Technique
Abstract
MgErxFe2-xO4 (x = 0.00, 0.05, 0.10) ferrites samples crystallize in a single-phase cubic spinel structure (Fd-3m), according to Rietveld-refined XRD patterns. Successful Er integration is demonstrated by the excellent match between calculated and observed profiles as well as the lack of subsequent phases. Lattice distortion caused by Er replacement without symmetry modification is reflected in small peak shifts. MgErxFe2-xO4 nanoparticles' UV-Vis absorption spectra show a wide absorption band in the 600 - 650 nm range, which is typical of spinel ferrites. Because of lattice distortion and variations in cation distribution, Er substitution alters the absorption intensity. Reduced absorbance from longer annealing times suggests better crystallinity and fewer states linked to defects. These findings show that the optical characteristics of MgErxFe2-xO4 ferrites are efficiently tuned by both Er doping and thermal treatment. All things considered, Er doping and annealing work together to effectively tune the optical band gap of MgErxFe2-xO4 ferrites, making these materials attractive options for photocatalytic, sensor, and visible-light-driven optoelectronic applications. The DSC curves of MgErxFe2-xO4 exhibit a broad endothermic zone with no abrupt transitions up to 400 °C, showing strong thermal stability of the spinel phase, and an endothermic peak below ~100 °C due to moisture elimination. The heat-flow behavior is slightly altered by Er substitution, indicating better lattice stabilization without phase transformation. Progressive crystallization and lattice relaxation are indicated by expanded DSC curves, which display a slow increase in heat-flow without noticeable crystallization peaks. The crystallization slope is somewhat altered by Er substitution, indicating improved thermal stabilization and defect-controlled grain development devoid of phase change. With the maximum melting and crystallization temperatures at x = 0.05, the TG-DTA curves demonstrate a significant dopant-dependent shift in thermal transitions, suggesting improved thermal stability. In line with previous results on doped ferrites, the variations in heat-flow intensity reflect dopant-induced lattice deformation and changed cation-oxygen bonding.