Engineering High Permeability:Mn–Zn andNi–Zn Ferrites

Abstract

Magnetic properties of polycrystalline spinel ferrites are of significant interest in scientific community. Of all, initial permeability is most important magnetic property for device fabrication. Mn-Zn and Ni-Zn ferrites are commercially most successful class of ferrites. Ferrites accommodate variety of cations in interstitial sites; type of cations, their occupancy at interstitial sites, grain size, pores, defects, or other imperfections in ferrites regulate their response to external magnetic stimulus. These factors are influenced by composition and preparation method. The failure of initial permeability of ferrites, to withstand variation in frequency of applied signal has fueled intense efforts in scientific community to optimize frequency stability of permeability. Therefore, improvement in their permeability is important from commercial perspective, and it further enables deeper insight into the dynamical link between microstructure and magnetic properties. This work presents a review of initial permeability in Mn-Zn and Ni-Zn ferrites with a focus on influence of intrinsic factors and frequency of applied signal. The work is an analytical assessment to provide framework for engineering high permeability in ferrites.

A review on MnZn ferrites: Synthesis, characterization and applications

“…In the class of soft ferrites, MnZn ferrites are preferred due to high permeability [122][123][124][125][126][127], saturation induction [128][129][130], low power losses [34,[131][132][133][134][135][136][137][138] and high magnetic induction [139,140]. MnZn ferrites are of great interest due to their wide range of applications such as hyperthermia applications [141], power applications [109][110][111], magnetic fluid [145], high frequency power supply, memory storage devices, TV sets, biomedicines [146], magnetic resonance, catalysis etc.…”

Li2MoO4‐based composite ceramics fabricated from temperature‐ and atmosphere‐sensitive MnZn ferrite at room temperature

“…In an inverse spinel, divalent cations occupy B‐sites with trivalent cations distributed in both A‐ and B‐sites. An intermediate cation arrangement is referred to as a mixed spinel . As the cationic composition affects the spinel structure, it is an important factor in addition to porosity and grain size in determining the electrical and magnetic properties of these ferrites .…”

“…An intermediate cation arrangement is referred to as a mixed spinel . As the cationic composition affects the spinel structure, it is an important factor in addition to porosity and grain size in determining the electrical and magnetic properties of these ferrites . To optimize the magnetic properties, an excess of iron oxide is often added .…”

“…In the case of MnZn ferrites, their relative permeability (μ r ) remains high up to several MHz before it deteriorates, whereas NiZn ferrites have a high μ r up to 100 MHz . However, these properties can be adjusted with a composite approach to meet the requirements of different applications . The properties of a composite are determined by its constituent phases, and thus the more abundant matrix phase dominates the effective properties of the final composite .…”

“…The general method for processing ceramic materials is the conventional solid‐state method which includes a high‐temperature sintering step . During sintering, thermally assisted mass transport leads to densification of the compressed powder into a solid piece at temperatures relatively close to, but always below, the melting point of the ceramic material.…”