Insight into the local atomic structure, optical, magnetic, and electrical polarization properties of Eu³+-substituted R-type hexagonal ferrite

The objective of the present study is to synthesize and investigate the local atomic structural, magnetic, electrical, and optical properties of Eu³+-substituted R-type hexagonal ferrite (Sr₁₋xEuxMn₂Fe₄O₁₁) with varying Eu concentrations (x = 0.0, 0.02, 0.06, and 0.1), using the sol–gel method. X-ray diffraction (XRD) patterns and X-ray absorption fine structure (XAFS) analysis confirmed the formation of a single-phase structure for all compositions. The incorporation of Eu³⁺ into the R-type hexaferrite influenced the structural parameters, with the positive slope of the Williamson–Hall (W–H) plot indicating the presence of tensile strain in the lattice. The magnetic characteristics of the synthesized samples were examined using a vibrating sample magnetometer (VSM), revealing a soft ferrimagnetic nature. The saturation magnetization was found to range from 5.22 to 2.21 emu/g, accompanied by an increase in coercivity from 274.54 to 283.35 Oe. Ferroelectric P–E (polarization–electric field) loops demonstrated a decrease in both saturation and remanent polarization upon Eu³⁺ substitution, indicating the lossy nature of the materials. UV–visible spectroscopy showed broad light absorption in the visible to near-infrared (700–1100 nm) range, suggesting potential applications in photothermal therapy (PTT). The optical band gap values were found to range from 3.22 to 3.40 eV. Furthermore, photoluminescence (PL) spectra exhibited broad emission from the ultraviolet (UV) to the infrared (IR) region, with the x = 0.06 composition presenting the most intense emission peak. Based on these characterizations, the synthesized materials show promise for use in clinical hyperthermia for cancer treatment and in optoelectronic applications.