Synthesis and Characterization of Spinel Ferrite Nanoparticles for Electronic Applications: A Review

Abstract

Abstract

Spinel ferrites (MFe2O4, where M is a divalent transition-metal cation) are among the most important soft magnetic oxides in modern electronics, because they combine high electrical resistivity, tunable magnetic permeability, and low eddy-current losses at high frequencies. At the nanoscale their behavior depends on how cations are distributed over the tetrahedral (A) and octahedral (B) sublattices, on surface and quantum-confinement effects, and on the microstructure that the chosen synthesis route produces. This review examines these relationships in a systematic way. We compare the main top-down and bottom-up synthesis strategies, namely solid-state reaction, high-energy ball milling, co-precipitation, hydrothermal synthesis, microemulsion, and sol–gel auto-combustion, in terms of phase purity, particle morphology, and cation distribution. We then outline a multi-technique characterization framework that brings together X-ray diffraction, infrared and Raman spectroscopy, X-ray photoelectron spectroscopy, electron microscopy, gas-sorption porosimetry, magnetometry, and broadband dielectric spectroscopy. Particular attention is given to transition-metal and rare-earth substitution as a way of tuning saturation magnetization, coercivity, magnetocrystalline anisotropy, and dielectric loss. These material-level insights are then connected to high-frequency inductors and planar transformers, microwave circulators and absorbers, electromagnetic-interference shielding, magnetic recording media, and gas and magnetoelastic sensors. The review closes with a discussion of the remaining bottlenecks, the difficulties of industrial scale-up, and the research directions that appear most promising.