Physical properties of terbium-incorporated nanosized Li0.4Zn0.4Fe2.2O4 spinel ferrites: a new perspective

Abstract In the current study, we examined the impact of excess rare-earth Tb 3+ ions on the structural, morphological, magnetic, dielectric, and optical characteristics of non-stoichiometric Li 0.4 Zn 0.4 Tb x Fe 2.2 O 4 (where x = 0.0 and 0.025). X-ray diffraction (XRD) confirms that the samples were synthesized as cubic spinel nano ferrites. The crystallite sizes of the samples were calculated using the Scherrer and Williamson-Hall (W–H) models. The surface topography of nanoparticles was studied using the Brunauer–Emmett–Teller (BET) analysis. The specific surface area increased from 33.42 m 2 /g for LZFO to 44.37 m 2 /g for LZTFO. The remanent magnetization of Tb 3+ incorporated into LZFO rose from 4.868 to 10.713 emu/g, reflecting an increase of 120%. This enhancement can be linked to the alteration interactions between the A and B sites, as well as to the significant magnetic moment and strong spin–orbit coupling induced by the Tb 3+ ions. Based on the enhancements in saturation magnetization (61.020–65.124 emu/g), anisotropy constant (2684–5436 Oe), and coercive field (42.707–80.106 Oe) of the nano ferrites, the samples are well suited for high-density recording media and electromagnets. The real dielectric constant, AC conductivity, and Cole–Cole diagram of the Tb 3+ incorporated sample were investigated. The optical energy gap for the samples was calculated using four different methods and was found to decrease following the incorporation of Tb 3+ . The Urbach energies of the synthesized samples were investigated, in addition to the refractive index and extinction coefficient. The Wemple-DiDomenico model was used to examine dispersion energies. Mulliken electronegativity theory was used to calculate the conduction and valence bands potentials.