Deciphering the characterization of Ni_0.7−xZn_0.3Mg_xFe₂O₄ nano ferrites: spectroscopic evaluation of structural parameters via Debye-Scherrer, Williamson-Hall, size-strain, Halder-Wagner plot, and optical methods

Ni_0.7−xZn_0.3Mg_xFe₂O₄ spinel ferrite nanoparticles were synthesized via self-combustion. Structural, morphological, elastic, optical, and photoluminescence properties were examined using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Field emission scanning electron microscope (FESEM), Transmission electron microscope (TEM), selected area electron diffraction (SAED) pattern, Ultraviolet–Visible (UV–Vis) and Photoluminescence (PL) spectroscopy. XRD confirmed a cubic lattice with a preferred (311) orientation. Increasing Mg²⁺ ion concentration enhanced lattice parameters due to its larger ionic radius compared to Ni²⁺. Crystallite sizes were analyzed using Debye-Scherrer, Williamson-Hall, Halder-Wagner, and Size-Strain methods. XRD data revealed an unusual cation distribution over tetrahedral and octahedral sites. FTIR spectra confirmed the spinel ferrite structure with prominent peaks for these sites. TEM images showed spherical nanoparticles, and SAED pattern confirmed the cubic structure. Band gaps from Tauc’s plots ranged between 2.52 and 2.78 eV. PL spectra showed three sub-bands: near band edge emission, violet band, and blue band.