Correlation among the structural, electric and magnetic properties of Al³⁺ substituted Ni–Zn–Co ferrites

Abstract

This study explored the structural, electrical, and magnetic properties of diamagnetic aluminium (Al³⁺) substituted nickel-zinc-cobalt (Ni-Zn-Co) mixed spinel ferrites, though the research on this area is in the infancy stage. Single-phase cubic spinel structures with the <i>Fd</i>3̄<i>m</i> space group of the synthesized Ni_0.4Zn_0.35Co_0.25Fe_(2-<i>x</i>)Al _<i>x</i> O₄ (0 ≤ <i>x</i> ≤ 0.12) ferrite samples were confirmed by X-ray diffraction (XRD) analysis. The average particle size ranged from 0.67 to 0.39 μm. Selected area electron diffraction (SAED) patterns were indexed according to the space group <i>Fd</i>3<i>m</i>, representing the particle's crystallinity. The optical band gaps ranged from 4.784 eV to 4.766 eV. Frequency-dependent dielectric constants and ac conductivity measurement suggested that the prepared ferrites were highly resistive. Relaxation times were reduced to a low value from 45.45 μs to 1.54 μs with the composition <i>x</i>. The Curie temperatures (<i>T</i> _c) were 615-623 K for all samples. Real part permeabilities (<i>μ</i> ^/) were relatively stable up to an extended frequency range of 10⁶ Hz with relative quality factors (RQF) of around 10³. Tuning of the properties indicates that the fabricated ferrites may be promising for high-frequency electronic devices.