Understanding the impacts of Al⁺³-substitutions on the enhancement of magnetic, dielectric and electrical behaviors of ceramic processed nickel-zinc mixed ferrites: FTIR assisted studies

Al-incorporated Ni-Zn ferrites (Ni_0.65Zn_0.35Al_xFe_{2 − x}O₄, where x = 0, 0.03, 0.06, 0.09, 0.12) synthesized via standard ceramic technology were investigated for their structural, magnetic, dielectric, and electrical properties. Al substitution plays a remarkable role in refining the structural features and other properties of the ferrite particles. The bulk density, porosity and lattice parameters of Ni-Zn ferrites were decreased with increased Al-content while the X-ray density was reduced. XRD patterns confirmed the single-phase cubic spinel structure of the ferrites particles. The room temperature infra-red spectra shows the features of higher and lower energy bands detected at ν₂ ∼ 400–405 cm⁻¹ and ν₁ ∼ 590–594 cm⁻¹, respectively corresponded to tetrahedral (T-band) and octahedral vibration (O-band) complexes that also confirm the formation of Ni-Zn inverse spinels. The real part of the complex initial permeability, Curie temperature, ac resistivity and loss tangent of the ferrite powders were reduced while the quality factor was enhanced with the subsequent Al-substitution. The observed bi-layer space charge polarization feature was believed to correlate the normal dielectric behavior of Al-substituted Ni-Zn matrix.