Investigation of Pb’s impact on the physical, optical, and magnetic characteristics of \({\mathbf{B}\mathbf{a}}_{0.5-\mathbf{x}}{\mathbf{S}\mathbf{r}}_{0.5}{\mathbf{P}\mathbf{b}}_{\mathbf{x}}{\mathbf{F}\mathbf{e}}_{12}{\mathbf{O}}_{19}\) hexaferrite

Ba_0.5-xSr_0.5Pb_xFe₁₂O₁₉ hexaferrites (x = 0, 0.1, 0.2, 0.3, and 0.5) prepared by the co-precipitation method, revealed the formation of M-type hexaferrites with crystallite sizes varying from 42.81 to 60.96 nm. Fourier transform infrared spectra (FTIR) indicated the formation of hexaferrites. Scanning electron microscope (SEM) analysis confirmed hexagonal morphology. Transmission electron microscopy (TEM) micrographs, high-resolution transmission electron microscopy (HRTEM) pictures, and selected area electron diffraction (SAED) patterns further supported the nanoparticle characteristics. SAED analysis showed clear and well-defined circular rings, corresponding to the reflection planes observed in X-ray powder diffraction (XRD) analyses. X-ray photoelectron spectroscopy (XPS) was performed to examine the electronic structure, while energy-dispersive X-ray spectroscopy (EDX) investigation proved the elements’ existence. The direct optical energy band gaps ( \({\mathrm{E}}_{\mathrm{g}}\) ${\mathrm{E}}_{\mathrm{g}}$ ), as determined through Tauc plots, decreased from 3.11 to 2.95 eV in an inversely proportional manner to D, indicating the quantum confinement effect. Photoluminescence (PL) spectra showed emissions at 335 nm for all synthesized compounds. The vibrational sample magnetometer (VSM) measurements showed strong ferromagnetic behavior, with a decrease in saturation magnetization ( \({\mathrm{M}}_{\mathrm{s}}\) ${\mathrm{M}}_{\mathrm{s}}$ ) from 56.33 to 38.83 emu/g, coercive fields ( \({\mathrm{H}}_{\mathrm{c}}\) ${\mathrm{H}}_{\mathrm{c}}$ ) from 4388.3 to 3289.3 G, and squareness ratios from 0.49 to 0.43. The decrease in coercivity ( \({\mathrm{H}}_{\mathrm{c}}\) ${\mathrm{H}}_{\mathrm{c}}$ ) with Pb incorporation is attributed to significant demagnetizing-like interactions caused by a rise in particle size and a reduction in anisotropy energy rising from Pb doping. Effective crystalline anisotropy constants ( \({\mathrm{K}}_{\mathrm{eff}}\) ${\mathrm{K}}_{\mathrm{eff}}$ ) decreased from 2.37 × 10⁵ to 1.03 × 10⁵ Erg/g, categorizing the materials as hard magnets ideal for high-density magnetic recording plus permanent magnet production.