Zn Ferrite Research Articles

Binder jet 3D printing of Mn–Zn ferrite soft magnet toroidal cores

Traditional powder processing methods for Mn–Zn ferrites limits design freedom and scalability of producing customized soft magnetic cores. In this work, binder jet 3D printing techniques were applied to commercially available Mn–Zn ferrite powders and toroidal cores were successfully fabricated. As-printed Mn–Zn ferrite powders were sintered at different temperatures between 1300 and 1400 °C, resulted in an optimized single-phase spinel at 1350 °C. Microstructural characterization revealed high porosity remained for binder jetted materials and various magnetic property measurements were performed on sintered cores. Despite high porosity, the saturation moments normalized by mass remained similar between binder jetted and traditionally compacted samples. Two-winding method measurements indicated a large demagnetizing field for binder jetted samples. Effective medium theory model was used to estimate the effect of remnant porosity on measured magnetic permeabilities. Importance of novel concepts to successfully realize dense cores through additive manufacturing pathways such as binder jetting is highlighted.

Insight mechanism of magnetic activated catalyst derived from recycled steel residue for black liquor degradation

The present work deals with developing a method for revalorizing steel residues to create sunlight-active photocatalysts based on iron oxides. Commercial-grade steel leftovers are oxidized under different combinations of pH and temperature (50–90 °C and 3 ≥ pH ≤ 5) in a low energy-intensive setup. The material with the highest production efficiency (yield > 12%) and magnetic susceptibility (χm = 387 × 10−6 m3/kg) was further explored and modified by diffusion of M2+ (Zn and Co) ions within the structure of the oxide using a hydrothermal method to create ZnFe2O4, CoFe2O4 and combined Co–Zn ferrite. (Co–Zn)Fe2O4 displayed a bandgap of 2.02 eV and can be activated under sunlight irradiation. Electron microscopy studies show that (Co–Zn)Fe2O4 consists of particles with diameters between 400 and 700 nm, homogeneous size, even distribution, and good dispersibility. Application of the developed materials in the sunlight catalysis of black liquors from cellulose extraction resulted in a reduction of the Chemical Oxygen Demand (− 15% on average) and an enhancement in biodegradability (> 0.57 BOD/COD) after 180 min of reaction. Since the presented process employs direct solar light, it opens the possibility to large-scale water treatment and chemical upgrading applications.

Impact of carbon dots on the structural, morphological, magnetic, and electrochemical performance of Zn ferrite for energy storage applications

Magnetic core-shell Zn ferrite and carbon dots (C-dots) composite have been synthesized in this work using a simple coprecipitation and hydrothermal process, respectively. X-ray diffraction (XRD) patterns demonstrate an inverse spinel structure of Zn ferrites; the lattice parameter has decreased from 8.19 Å to 8.10 Å with C-dots. Scanning electron microscopy (SEM) images reveal rods-like structures for C-dots, and in the composite case, it is uniformly dispersed using low contrast consecutive C-dot layers to produce a core-shell structure. Zn ferrites are non-uniform in size, whereas C-dots and their composites are in uniform shape according to SEM images. The energy dispersive X-ray (EDX) study indicates that the substitution has been successful. For Zn ferrites, and composite, the Fourier transform infrared (FTIR) spectra shows that the absorption band of the tetrahedral site at 990 cm−1, and 870 cm−1, respectively. Different bonds in the infrared spectrum match specific function groups and bonding in various chemicals. The vibrating sample magnetometry (VSM) results indicates that the composite displays ferrimagnetic behavior. The specific capacity for composite has been found to be 2351 and 1790 F/g using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements, respectively. Higher electrochemical performance of the prepared composites may be helpful for energy storage systems.

Evaluating Zn ferrite (ZnxFe3-xO4; 0 ≤ x ≤ 1) for alkaline water oxidation: electrochemical and spectro-electrochemical study

Evaluating Zn ferrite (ZnxFe3-xO4; 0 ≤ x ≤ 1) for alkaline water oxidation: electrochemical and spectro-electrochemical study

Solvent‐Less Synthesis of Compositionally Tuned Mixed Metal (Ni−Zn) Ferrites for Enhanced Electrocatalytic Water Splitting and Supercapacitance

AbstractExploring efficient, abundant, economical and stable materials for sustainable energy applications, such as electrochemical water splitting and supercapacitance, is a challenging task. Mixed transition metal spinel ferrites can rationally be customized to attain these features and deliver enhanced electrochemical activity. The catalytic performance of spinels is remarkably influenced by tuning the cationic occupancy at the tetrahedral or octahedral position. Herein, a set of spinel Ni1‐xZnxFe2O4 (0≤x≤1) nanocomposites were obtained via a scalable solventless thermolysis of metal acetylacetonate precursors at relatively mild temperatures. A suite of techniques such as powder p‐XRD, EDX, SEM, TEM, HRTEM, and SAED were employed to confirm the formation of the Ni−Zn ferrite solid solutions. It was found that small amounts of Ni at tetrahedral sites were beneficial for charge storage and hydrogen evolution. For instance, Ni0.2Zn0.8Fe2O4 nanocomposite demonstrated superior HER activity with a much lower overpotential of 87 mV compared to the pristine NiFe2O4 (213 mV) or ZnFe2O4 (164 mV) catalysts. However, Ni‐occupied tetrahedral sites were not suitable for OER, whereby the pristine ZnFe2O4 displayed high catalytic activity with an overpotential of 330 mV, outperforming other electrode compositions. The study helps to identify suitable compositions and site tuning for HER, OER and supercapacitors.

Effect of zinc substitution on structural, electrical, dielectric and magnetic properties of magnesium nano-ferrites prepared by co-precipitation route

Zinc substituted Magnesium ferrites synthesized by using Co-precipitation method. The structural characterisations of samples are carried out and formation of single-phase nickel ferrite was substantiated through powder X-ray diffraction. The lattice parameters were calculated that are in the range 8.323–8.361 Å.Surface morphology of samples were also investigated through Scanning electron microscopic (SEM) analysis. SEM images revealed clear grain structures of synthesised samples. Magnetic measurements showed the ferromagnetic behaviour, analysed through vibrating sample magnetometer (VSM) while magnetic parameters obtained using VSM measurementat room temperature. MS and HC were found to decrease with increases in the Zn concentration due to non-magnetic behaviour of zinc. The dielectric dispersion for the Mg–Zn ferrites were determined as a function of frequency (50 Hz to 5 MHz). The dielectric constant and the loss tangent decrease expeditiously with incrementing frequency, and then reaches a constant value. The semiconducting behaviour of Mg-Zn ferrites proved by measuring resistivity as a function of temperature and materials are showing thermistor relatively good thermistor constants, they can be utilized as thermistors. The results were discussed in detail in this research article.

Mn–Zn ferrite foam concrete: Enhanced electromagnetic wave absorption and pore structure by incorporating carbon fibers

In this study, an absorbent composite of carbon-fibre-reinforced Mn–Zn ferrite foam concrete was fabricated. The influence of carbon fibre (CF) concentration on the mechanical and electromagnetic wave (EMW) absorption characteristics of Mn–Zn ferrite foam concrete within the 0.2–5GHz were investigated. Key performance indicators, such as compressive and flexural strengths, electromagnetic parameters, reflection loss, and absorption bandwidth were thoroughly analysed. The pore size and distribution were examined by X-ray computed tomography (CT) to reveal the EMW absorption mechanism. The findings indicate that CF effectively mitigates agglomeration in Mn–Zn ferrites, enhancing dielectric and magnetic losses synergistically, which improves not only the mechanical properties but also the EMW absorption capacity of Mn–Zn ferrite foam concrete. The optimal wave absorption performance was observed at a CF content of 0.3 wt%, yielding an impressive absorption bandwidth of 1.46 GHz and a minimum reflection loss (RLmin) of −28.75 dB. A noteworthy observation was the inverse correlation between the CF doping level and resistivity. The attenuation constant peaked at 108.13. When the CF content reached 1.2 wt %, the composite attained its percolation threshold, manifesting a resistivity of 145.4 Ω·m.

Arguments on the estimation of V ion distribution at various sites contributing to saturation magnetization in Mn–Zn ferrites

Mn0.6Zn0.4VxFe2-xO4 (x = 0.00–0.10, in steps of 0.02) are synthesized by the solid-state reaction method with a sintering temperature of 1250 °C. X-ray diffraction of the samples confirms the formation of the spinel structure. The grain size is found to increase in morphological investigation of the surface of the samples. The distribution of cations upon vanadium doping in manganese zinc ferrites has not been widely studied before. This study highlights our attempt to formalize a cation distribution to explain our experimental results. Vanadium ions occupying B-sites in their trivalent form may explain the decreasing trend observed in the cell parameters and saturation magnetization, MS values. To support this, theoretical cell parameters and theoretical magnetic moments have been calculated.

Studies on the microstructure, magnetic, and electrical transport properties of Dy-substituted Mg–Cu–Zn ferrites

Studies on the microstructure, magnetic, and electrical transport properties of Dy-substituted Mg–Cu–Zn ferrites

Mechanical and thermal response of XFe2O4 (X = Zn, Ag and Co) spinel ferrites via IR-spectroscopy and first-principles calculations

The lack of comprehensive literature on the all-important aspect of the elasticity of spinel ferrites led to the hydrothermal synthesis of different (Co, Zn, Ag) spinel ferrites. IR spectroscopy revealed the characteristic absorption bands of metal-oxygen in all three compositions. The shifting of tetrahedral and octahedral bending vibrations towards higher frequencies owes to changes in inter-atomic and inter-ionic distances. Elastic parameters, wave velocities, and Debye temperature have been calculated using IR spectroscopy data. Elastic parameters have been higher for Co ferrites than Zn and Ag ferrites. The Poisson ratio seems to be consistent for different spinel ferrites. Shear wave velocity has been found to be higher than longitudinal wave velocity because perpendicular particle vibrations take higher energy than parallel vibrations. Wave velocities have been found to be higher in Ag ferrites than in the other two compositions. Debye temperature follows the same trend as elastic parameters. Additionally, we have confirmed the mechanical stability of the Co, Zn, and Ag ferrites using the first-principles calculations in the density functional theory (DFT) approach framework. Interestingly, the Co/Zn/Ag ferrites exhibit semiconducting nature with a band gap of 3.96/3.66/0.71 ev. Our study could pave the way for next-generation spintronic devices.

Impact of Magnesium on Structural and Morphological Study of Co–Zn Ferrites

Impact of Magnesium on Structural and Morphological Study of Co–Zn Ferrites

Significantly improved near-field communication antennas based on novel Ho 3+ and Co 2+ ions co-doped Ni–Zn ferrites

Significantly improved near-field communication antennas based on novel Ho ³⁺ and Co ²⁺ ions co-doped Ni–Zn ferrites

Novel Mn0.5Zn0.5Al0.1MgxLixFe(1.9-x)O4 nanoferrites: synthesis, theoretical cation distribution, and improving their dielectric properties

The effect of Mg2+–Li1+ ions in modifying the structural, electrical, and magnetic characteristics of nanocrystalline Mn–Al–Zn ferrites was examined experimentally and theoretically in the current study. The chemical co-precipitation method was used to create the investigated ferrite samples, which have the chemical formula (Mn0.5Zn0.5 Al0.1Mgx Lix Fe(1.9-x)O4) and concentration range of the substituent (0 ≤ x ≤ 0.2). The cation distribution of the investigated system was assumed and confirmed. Furthermore, the activation energy, AC resistivity, dielectric loss tangent, and dielectric constant were investigated in terms of their compositional dependence. The final results showed that the increasing of Mg2+–Li1+ concentration enhanced the physical and dielectric properties of the prepared samples. The experimental findings show also that as temperature rises, ε′, tan δ, and σ all increase but they all decrease as Mg2+–Li1+ content increases. With increasing Mg2+–Li1+ concentration, the AC resistivity of the prepared samples also continuously increased, resulting in the sample with x = 0.2 having high resistivity, which can be used in specific technical applications such as transformer cores.

Broadband and Tunable Microwave Absorption Properties from Large Magnetic Loss in Ni–Zn Ferrite

AbstractHighly effective electromagnetic (EM) wave absorber materials with strong reflection loss (RL) and a wide absorption bandwidth (EBW) in gigahertz (GHz) frequencies are crucial for advanced wireless applications and portable electronics. Traditional microwave absorbers lack magnetic loss and struggle with impedance matching, while ferrites are stable, exhibit excellent magnetic and dielectric losses, and offer better impedance matching. However, achieving the desired EBW in ferrites remains a challenge, necessitating further composition design. In this study, impedance matching is successfully enhanced and EBW in Ni–Zn ferrite is broadened by successive doping with Mn and Co , without incorporation of any polymer filler. It is found that Ni0.4Co0.1Zn0.5Fe1.9Mn0.1O4 material exhibits exceptional EM wave absorption, with a maximum RL of −48.7 dB. It also featured a significant EBW of 10.8 GHz, maintaining a 90% absorption rate (RL < −10 dB) for a thickness of 4.5 mm. These outstanding properties result from substantial magnetic losses and favorable impedance matching. These findings represent a significant step forward in the development of microwave absorber materials, addressing EM wave pollution concerns within GHz frequencies, including the frequency band used in popular 5G technology.

Magnetodielectric, elastic, Rietveld refinement and absorption properties of Nd–Cu co-doped Co–Zn nano ferrites: Development of meta-absorbers for wide frequency regime

Currently, Electromagnetic (EM) pollution is harmful to human health because of the generation and propagation of high-frequency EM waves from electronic devices. The absorbing materials with outstanding properties are highly desirable. Meta-absorbers with extraordinary electromagnetic wave absorption, outstanding EM shielding ability, and featured dissipation efficiency are still worth challenging in the surrounding environments. The meta-absorbers were fabricated, designed, and simulated to address the challenges. Nd–Co co-doped Co–Zn spinel nano ferrites (Co0.5Zn0.5-xCuxFe2-yNdyO4 with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, y = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10) were prepared. XRD, FESEM, FTIR, and VSM were used to study the structure, phase, vibrational, elastic, and magnetic features of the Nd–Co co-doped Co–Zn ferrites, respectively. Rietveld refinement of the Nd–Co co-doped Co–Zn ferrites was evaluated by FullProf software. Wyckoff locations and occupancy of the already present cations and anions were refined. The bond lengths and unshared-shared edges were determined using the Bertaut method. The detailed phase occurrence, force constant, and elastic features of Nd–Co co-doped Co–Zn ferrites were also investigated. The mixed shapes of grains like elliptical, circular, and hexagons were noticed from FESEM images. The magnetization and coercivity were reduced with the Nd–Cu doping. Switching field and high-frequency response were also presented for the Nd–Cu co-doped Co–Zn ferrite. The dielectric properties like complex permittivity and permeability depicted higher response at high frequency due to interfacial polarization in prepared ferrites. The reflection loss (RL) of −74.1 dB was noticed at 1.99 GHz for x = 0.4, y = 0.08. However, the reflection loss of −63.9 dB at 2.24 GHz was observed for x = 0.5, y = 0.1. Meta-absorbers of Nd–Cu co-doped NiZn were designed and simulated. The wideband absorptivity is depicted for Nd–Cu co-doped CoZn ferrite as substrate material at x = 0.0 y = 0.00, x = 0.1 y = 0.02, and the absorptivity remains highest for θ = 0 deg. The absorptivity significantly reduces with the increase of incidence angle. Meta-absorbers based on Nd–Cu co-doped Co–Zn ferrites are good future candidates for EMI (electromagnetic interference), MLCIs (multilayer chip inductors), electromagnetic shielding, and 5G-mobile antenna purposes in high-frequency applications.

Detailed investigation of Mn-substituted Zn ferrites for microwave applications up to 6 GHz

Mn-substituted Zn ferrites with chemical formula Zn1−xMnxFe2O4 (0.0, 0.1, 0.2, 0.3) were synthesised via sol-gel auto-combustion. The structural analysis reveals that tetrahedral lengths decrease while octahedral lengths increase due to strong affinity of large ionic radii Mn for octahedral sites as compared to Zn. Scanning electron microscopy reveals that the grain size of all the ferrites lies in the range 200–250 nm. Hysteresis loops of all samples show the coercivity to be several hundred Oersted, indicating the soft magnetic nature of spinel ferrites. High-frequency parameters like complex permittivity and permeability, direct conductivity and loss tangent were measured against varying frequencies (∼ 6 GHz) for a selected sample.

Effects of adding carbonyl Fe or Mn–Zn ferrite powders to fibre-based soft magnetic composites prepared via hybrid cold sintering/spark plasma sintering

This manuscript presents the preparation and characterisation of fibres-based soft magnetic composites that incorporates a secondary magnetic phase such as carbonyl Fe and Mn–Zn ferrite nanopowder. Amorphous Fe77.7Si7.5B15 at.% fibres were coated with a dielectric layer of ZnO via thermal evaporation. SEM-EDX investigations revealed that the thermal evaporation technique leads to a complete coating of the fibres with a ZnO coating having a thickness of 150–250 nm as demonstrated via STEM-EDX analysis. The hybrid cold sintering/spark plasma sintering technique was used for the first time for the preparation of soft magnetic composites. Substituting 10 wt% of ZnO with carbonyl Fe resulted in an increase in the saturation magnetisation of the composite from 0.61 T to 0.7 T. In contrast, substituting it with Mn–Zn ferrite led to a decrease in saturation magnetisation from 0.61 T to 0.5 T. The coercivity of the composites increased when ZnO was partially substituted with Fe or Mn–Zn ferrite, rising from 16.9 A/m to 22.7 A/m and 36.8 A/m, respectively. AC magnetic characterization revealed that the relative permeability of the composites remains constant across the entire frequency range tested for all composites. However, the introduction of carbonyl Fe or Mn–Zn ferrite led to a reduction in the relative permeability values of the composites from 1310 to 1200 and 890, respectively. The core losses of the composites were also influenced by the secondary magnetic phase used. The use of Mn–Zn ferrite or carbonyl Fe resulted in a significant increase in the hysteresis losses of the composites. When carbonyl Fe was used for partial substitution of ZnO, a substantial increase of the eddy currents losses of the composites was noted.

NANO STRUCTURE AND MAGNETIC PROPERTIES OF Zn FERRITE AND ZnCuNi FERRITE USING THE Co-PRECIPITATION METHOD

Zn Ferrite and ZnCuNi Ferrite with a composition of ZnFe2O4 and Zn0.9Cu0.05Ni0.05 Fe2O4 have been synthesis using the co-precipitation method. Zn Ferrite and ZnCuNi Ferrite have been synthesized at 100 oC. Structure, morphology and magnetic properties were obtained by the characterization of X-ray Difraction (XRD), Field Emission-Scanning Electron Microscope (FE-SEM) and Vibrating Sample Magnetometer (VSM). The X-Ray Diffraction (XRD) characterization showed the cubic spinel structure of Zn Ferrite and ZnCuNi Ferrite. The microstructure and magnetic properties have been changed with the addition of Cu2+ and Ni2+ to ZnFe2O4. The grain size increased from 13.4098 nm to 13.7184 nm. The VSM test results also showed an increase in saturation mangetization from 14.76 emu/g to 26.67 emu/g. Meanwhile, the magnetic coercivity value experienced the opposite, which decreased from 87.85 Oe to 87.65 Oe. The addition of Cu2+ and Ni2+ increases the magnetization of the spinel ferrite and decreases its magnetic coercivity.

Temperature dependence of complex permeability and power losses for Mn–Zn ferrites

Temperature dependence of complex permeability and power losses for Mn–Zn ferrites

Magnetic particle spectroscopy and magnetic particle imaging of zinc and cobalt ferrite nanoparticles: Distinct relaxation mechanisms

Magnetic particle imaging (MPI) is an emerging imaging method based on the nonlinear response of superparamagnetic tracers to a sinusoidal AC magnetic field. Higher harmonics obtained by the Fourier transform of acquired signals form a so-called magnetic particle spectrum, whereby straightforward evaluation of different nanoparticles as potential MPI tracers can be carried out. The shape of the spectra is largely dictated by the combined Néel and Brownian relaxation of superspins, whose relative contributions vary significantly depending on the tracer properties. The present study is focused on the comparison of several Zn ferrite and Co ferrite samples, selected for their different magnetic behaviors, together with the commercial tracer Resovist® (SH U 555 A). A new custom-made magnetic particle spectrometer and a commercial MPI system (Bruker) with comparable AC field amplitudes (∼14 mT) and frequencies (∼25 kHz) are used. Magnetic nanoparticles of Zn and Co ferrites have been synthesized by the thermal decomposition method and by the solvothermal/hydrothermal route, achieving four different samples of magnetic cores with the mean crystallite size in the range of 8–16 nm. From all of them, well-comparable silica-coated particles with a shell thickness of 5–6 nm have been prepared. To analyse the effect of the coating layer and hydrodynamic size, three additional samples have been supplemented: solvothermal Zn ferrite nanoparticles stabilized with a citrate monolayer, the same particles coated with 17 nm thick silica shell, and silica-coated Zn ferrite particles from the thermal decomposition with a higher degree of agglomeration. Fundamental characterizations of the nanomaterials by XRD, XRF, TEM, and DLS are followed by detailed investigations of their magnetic properties and structural peculiarities by SQUID magnetometry and 57Fe Mössbauer spectroscopy. Magnetic particle spectroscopy and subsequent MPI study demonstrate: (i) superior properties of Zn ferrite nanoparticles compared to their Co ferrite counterparts, (ii) only negligible to weak effect of the type/thickness of the coating on signal of Zn ferrite nanoparticles, (iii) comparable performance of the solvothermal Zn ferrite particles with a thin silica shell and of the Resovist® tracer, and importantly, (iv) that suitable choice of the magnetic phase enables to separate the contributions of the Néel and Brownian relaxation on the timescale of MPI.