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Ba0.5-xSr0.5PbxFe12O19 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 ( E 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 ( M s ) from 56.33 to 38.83 emu/g, coercive fields ( H c ) from 4388.3 to 3289.3 G, and squareness ratios from 0.49 to 0.43. The decrease in coercivity ( H 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 ( K 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. [ABSTRACT FROM AUTHOR]

The structural properties of (x)CuO/(1-x)CdFe2O4 nanocomposites for x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1.0 were studied. The X-ray diffraction (XRD) patterns confirmed the existence of both phases with a secondary phase of α-Fe2O3. The Fourier-transform infrared spectroscopy (FTIR) characterization showed the vibrational bands of the synthesized samples. The high resolution transmission electron microscopy (HRTEM) micrographs revealed the presence of CuO, CdFe2O4, and α-Fe2O3 phases and showed the polycrystalline nature of the prepared nanocomposites. The scanning electron microscope (SEM) study exhibited the morphology of the prepared nanostructures and indicated the agglomeration between them. The energy-dispersive X-ray spectroscopy (EDX) results revealed the presence of all chemical elements within the synthesized nanocomposites. Emission peaks of the samples were analyzed via Photoluminescence (PL) deconvolutions which approved the interface defects. The Mössbauer study showed the presence of hematite impurity and the results were coherent with XRD findings. The obtained M-H loops from the vibrating-sample magnetometer (VSM) analysis depicted a paramagnetic nature of CuO and showed the ferromagnetic behavior of the nanocomposites. [ABSTRACT FROM AUTHOR]