Soft Magnetic Applications Research Articles

(Zn + Co) co-doped CdO thin films with improved figure of merit values and ferromagnetic orderings with low squareness ratio well suited for optoelectronic devices and soft magnetic materials applications

The present study focuses on the suitability of CdO thin films towards optoelectronic and spintronic devices through (Zn + Co) co-doping. Para to ferromagnetic transition mediated by oxygen vacancies takes place in the CdO:Zn thin films through Co doping which was acknowledged from the photoluminescence studies. Defect level peaks observed in the PL spectra at 411, 460 and 494 nm are associated with metal interstitials (Cdi, Zni, Coi), singly ionized oxygen vacancies (Vo+) and oxygen vacancies (Vo), respectively. The deep-level or trap state emission due to the ionized oxygen vacancies is observed at 521 nm. XRD analysis indicate that the undoped, Zn-doped (CdO:Zn) and (Zn + Co) co-doped CdO thin films have cubic structure with (1 1 1) plane being the preferential one. The crystallite size of pure CdO decreases with Zn-doping and with Co co-doping it increases. Cauliflower shaped nanostructures are evinced for the (Zn + Co) co-doped films. Increased optical transparency and decreased sheet resistance were observed for the (Zn + Co) co-doped films. Increased Haacke’s quality factor observed for the (Zn + Co) co-doped films confirmed their potential for optoelectronic devices.

Fabrication of high magnetic performance Fe–50Ni alloy by powder injection molding

ABSTRACT Fe–50Ni alloy is widely used for soft magnetic applications due to attractive magnetic properties. In this study, Fe–50Ni soft magnetic alloy was produced by powder injection molding. The influence of sintering parameters was investigated on the density, grain size, and magnetic properties. The injected parts were sintered at 1300–1375°C for 2–14 h with subsequent controlled slow cooling. It has found that permeability and magnetic induction improved with increasing sintering time and temperature, whereas the coercivity was reduced significantly. The sintered density and grain size of 98% and 240 µm were obtained in this study. Consequently, excellent magnetic properties of Fe–50Ni were achieved. The values of magnetic permeability and saturation induction were 50,240 and 1.52 T, respectively.

Magnetic Properties and Structure of Products from 1.4540 Stainless Steel Manufactured by 3D Printing

Magnetic properties and structure of the 1.4540 (S15500) stainless steel products manufactured by additive technology using the selective laser melting method (SLM) were studied. The structure of the SLM alloy differs from the conventional 1.4540 stainless steel. The volume fraction of austenite of 34% is found in the SLM sample. After solution treatment, the austenite is not observed. The martensitic thin plates and precipitations are observed in both as-build and solutionized samples. The solution treatment at standard temperature of 1038°C can be successfully used for the SLM 1.4540 steel products. Magnetic properties of the SLM 1.4540 stainless steel allow considering this material as applicable for soft-magnetic applications requiring high strength and high corrosion resistance.

Fe-Ga-Tb alloys for soft magnetic applications

The current paper deals with the influence of Tb doping on magnetic and magnetostrictive properties of Fe-19 Ga-xTb (x up to 0.37 at%) and Fe-27.4 Ga-xTb (x up to 0.5 at%) alloys at room temperature by vibrating sample magnetometry and strain gauge methods. The magnetocrystalline anisotropy constant and the magnetic permeability are improved in Fe19 Ga-xTb alloys upon Tb addition. A significant enhancement of the magnetostriction up to ≈ 235 ppm in Fe-19 Ga-0.37 Tb alloys is observed.Alloying of Fe-27.4 Ga with 0.3 at%Tb increases the magnetization, permeability, and magnetostriction, and decreases the coercivity, remanent magnetization, and hysteresis losses. Beyond this Tb content, a considerable amount of the phase enriched in Ga and Tb precipitates, which opposes magnetic domain wall motions and declines the magnetic properties.An improvement of the magnetic properties in Fe-Ga-Tb alloys might be correlated to the magnetocrystalline anisotropy and the localized strain induced by Tb. The present work demonstrates that the full potential of Fe-Ga-Tb alloys is yet to be explored for engineering soft magnetic applications.

Influence of temperature on the magnetic properties of nanostructured Fe-49 wt.% Co-2 wt.% V alloy powder synthesized by mechanically milling pre-alloyed gas-atomized powder

Abstract The magnetic properties of nanostructured Fe-49 wt.% Co-2 wt.% V alloy powder, synthesized by mechanically milling pre-alloyed gas-atomized powder, were investigated from cryogenic to high temperatures (60–900 K). At cryogenic temperatures, the as-milled nanostructured alloy powder exhibited stable magnetic properties. The decrease in MS was by a minuscule ∼2 %—from ∼212 ± 1 Am2/kg (at 300 K) to ∼217 ± 2 Am2/kg (at 60 K), and the increase in HCI was by a modest (∼8%)—from ∼6.1 kA/m (at 300 K) to ∼6.6 kA/m (at 60 K). At high temperatures (>300 K), both MS and HCI decreased. Annealing improved the soft-magnetic properties of the as-milled alloy powder. The annealed alloy powders retained their nanostructure—grain size ∼15–30 nm. The as-milled alloy annealed at 900 K showed the highest MS and the lowest HCI among all the other annealing temperatures—MS increased by ∼7%–∼225 ± 1 Am2/kg and the HCI decreased to ∼1.0 kA/m. The annealed nanostructured Fe-49 wt% Co-2 wt.% V alloy powder exhibited magnetic properties comparable to a few annealed nanostructured Fe- Co-based alloys. The annealed nanostructured alloy powder displayed fairly stable magnetic properties over a wide range of cryogenic temperatures. The annealed Fe-49 wt.% Co-2 wt.% V alloy powder is better suited for soft-magnetic applications than the as-milled powder, from ambient to cryogenic temperatures.

Nanostructured Zn-Substituted Nickel Ferrite Thin Films: CMOS-Compatible Deposition and Excellent Soft Magnetic Properties

Nanostructured $\text{Ni}_x\text{Zn}_{1-x}$ Fe2O4 ( $x$ = 1, 0.5) films, about 1.5 µm thick on Si (100) substrates, were deposited using a low-temperature ( $A_{1g}$ vibration mode in Raman spectra of both films reveals a ‘‘far-from-equilibrium’’ crystallographic inversion induced by the MAS process. Its effect on the magnetic characteristics of the films is analyzed here. Both films exhibit in-plane ( $xy$ plane) isotropy with very low room-temperature coercivities, 25 Oe for NF and 35 Oe for ZNF, which is essential for high-frequency, soft magnetic applications. The presence of interparticular dipolar interaction in both films is confirmed from temperature-dependent magnetization measurements made under different dc bias fields. The CMOS-compatible ferrite processing and superparamagnetic Ni-ferrite and NiZn-ferrite thin films presented here can meet upcoming technological needs in on-chip integrated passive devices.

In situ synthesis of Hägg iron carbide ([formula omitted]) nanoparticles with a high coercivity and saturation magnetization

Magnetic nanoparticles (NPs) suffer from poor magnetic properties (coercivity and saturation magnetization) compare to their bulk. Synthesis of Hägg iron carbide, Fe5C2 magnetic nanoparticles (NPs) was still a challenge for the pure phase and the large-scale production. Herein, a chemical solution route was proposed to obtain pure Fe5C2 phase using amorphous Fe NPs as iron feedstock in presence of Oleylamine (OAm) at elevated temperature. X-ray diffraction results reveal the pure Hägg iron carbide phase for various reaction time from 30 min to 9 h. Fe5C2 NPs show the same morphology as Fe NPs by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Amorphous Fe NPs catalyze the cleavage of CC bonds of OAm at elevated temperature as well act as a template for the in situ nucleation and growth of Fe5C2 NPs. The saturation magnetization of Fe5C2 NPs are 140 emu/g and 123 emu/g for 5 K and 298 K, respectively. The coercive force of Fe5C2 NPs are 452 Oe (298 K) and 703 Oe (5 K), demonstrating the ferromagnetic behavior. The magnetic Fe5C2 NPs showed the high coercivity and saturation magnetization on the nanoscale, revealing the Fe5C2 NPs being a promise candidate for the soft magnetic application such as magnetic medium. This paper presents a convenient procedure to synthesize Hägg iron carbide nanoparticles and may promote its further study in formation mechanism and application such as catalysis.

Printable Hierarchical Nickel Nanowires for Soft Magnetic Applications.

Hierarchical nickel nanowires (h-NiNWs) were synthesized by a simple reduction method and their electrical, magnetic, and electromagnetic characteristics were investigated. These nanowires possess a high magnetic saturation (Ms) of 51 emu/g and also a coercivity (Hc) of 34.5 Oe, which makes them suitable for soft magnetic sensor applications. Hall transport is being reported for the first time for h-NiNWs, and electrical conductivity at room temperature was studied to assess their applicability as a Hall sensor wherein the Hall coefficient RH was found to be −1.39 × 10–12 Ω cm/Oe. Electromagnetic characterization of synthesized h-NiNWs shows excellent microwave shielding effectiveness of above 24 dB for the Ku band (12.4–18 GHz) and a maximum value of 32 dB at 14 GHz for a sample with a thickness of about 1 mm. A room-temperature-curable screen-printable ink was formulated using the synthesized magnetic nanostructures and printed on different flexible substrates. Printed patterns show promising ferromagnetic properties, and they could be potential candidates for soft magnetic sensor applications.

Formation and Magnetic Properties of Nanocomposites in Rapidly Solidified Fe42Ni41.7C7Si4.5B3.9P0.9 (at%) Ribbons

A novel nanocomposite structure comprising ~ 20-nm face-centered cubic Fe50Ni50 nanocrystals embedded within an amorphous matrix has been developed directly from a liquid alloy of Fe42Ni41.7C7Si4.5B3.9P0.9 (at%) through melt-spinning. Grain growth kinetics was significantly limited by the amorphous phase formed between nanocrystals. Glass forming elements rejected from nanocrystals stabilize the amorphous phase restricting further growth of nanocrystals. The nanocomposite ribbon exhibits excellent soft magnetic properties compared to those of the conventional micron-scale microstructured Fe50Ni50 alloy known as 50 Permalloy. When the as-melt spun ribbon was heated to 600 °C, two exothermic events occurred. The formation of metastable C-rich Fe3Ni and Si- and P-rich FeNi phases at low temperatures was confirmed by detailed transmission electron microscopy analysis. The hard magnetic behaviors of these metastable phases were estimated based on the hysteresis curve analysis results obtained from a ribbon heated to 600 °C. Through proper addition of glass-forming elements to FeNi-based alloys, nanocomposites with superior soft magnetic properties were effectively fabricated for massive practical soft magnetic applications.

Modeling of stress relaxation kinetics of amorphous Fe0.7Nb0.1Zr0.1Ti0.1 alloy powder: A novel approach based on differential thermal analysis

In this study, the stress relaxation of amorphous Fe0.7Nb0.1Ti0.1Zr0.1 alloy was investigated by differential thermal analysis (DTA) to enhance the soft magnetic properties. Amorphous Fe0.7Nb0.1Zr0.1T0.1 alloy was produced by mechanical alloying technique using the mixture of pure elements and without adding metalloids. It was found that the stress relaxation process follows the Johnson-Mehl-Avrami model and the mechanism was volume diffusion control with three dimensional growth of the nuclei. The relation of stress relaxation progress (α), with time was proposed as: dαdt=βdαdT=3.04exp−4312RT1−α−ln1−α0.37. The final achieved microstructure leads to higher saturation magnetization and lower coercivity that are favorable for soft magnetic applications.

NiZnCu-ferrite coated iron powder for soft magnetic composite applications

Soft magnetic composites (SMCs) comprised of ferrimagnetic and electrically insulating coating materials for iron powder are capable of increasing frequency ranges and efficiency of electromagnetic devices, nominally electric motors. Soft ferrites can withstand stress relieving temperatures and allow for reduction in eddy current contributions while minimally effecting magnetic performance. This work demonstrates the effectiveness of a NiZnCu-ferrite coating material of 5 wt%, 10 wt%, and 15 wt% on iron powder using traditional press and cure (700 °C) powder metallurgy techniques. Powder properties such as apparent density and Hall flow rate are used to determine effect of acoustic mixing procedure on coating uniformity. An increase in resistance and porosity are found for increasing coating amount, with subsequent decreases in density, permeability, and magnetic saturation. We find lower core loss values for increasing coating amount, related to eddy current loss, however, lower induction levels are also seen. Our work highlights the importance of soft ferrites, more specifically Ni0.5Zn0.3Cu0.2Fe2O4, and their ability to vastly improve SMC developments using more traditional powder metallurgy (PM) techniques.

The effect of surfactant on the structure, composition and magnetic properties of electrodeposited CoNiFe /Cu microwire

In this work, the constant current electrodeposition of a ternary CoNiFe alloy onto a copper microwire from borate baths containing three surfactant additives was compared. The additives were sodium dodecyl sulfate (SDS) as an anionic surfactant, Triton X-100 as a nonionic surfactant, and the ionic liquid (IL) 1-dodecyl-3-methylimidazolium chloride) [C12mim]Cl(as a cationic surfactant. The scanning electron microscopy of the film surfaces showed that the coatings are compact and crack-free, but morphological differences were observed. The films prepared in the IL under optimized experimental conditions showed mechanical stability, high saturation magnetization (79 emu/g), and a GMI ratio of 183.4% at 1.5 MHz, which make them promising candidates for soft magnetic applications. The effect of current density, pH, IL concentration, and metal ion concentration on the current efficiency and the alloy composition was systematically investigated. Anomalous co-deposition under a current density of 29 mA/cm2 and pH of 2.5 in the presence of 1.2 g/L IL for a deposition time of 120 min lead to 30 μm thick Co17Ni53Fe30 alloy coatings with a nanocrystalline/amorphous structure.

Microstructure, soft magnetic properties and applications of amorphous Fe-Co-Si-B-Mo-P alloy

DC thermomagnetic properties of Fe51Co12Si16B8Mo5P8 amorphous alloy in the as-quenched and after annealing below crystallization temperature are investigated. They are related to deviations in the microstructure as revealed by Mössbauer spectrometry. Study of AC magnetic properties, i.e. hysteresis loops, relative permeability and core losses versus maximum induction was aimed at obtaining optimal initial parameters for simulation process of a resonant transformer for a rail power supply converter. The results obtained from numerical analyses including core losses, winding losses, core mass, and dimensions were compared with the same parameters calculated for Fe-Si alloy and ferrite. Moreover, Steinmetz coefficients were also calculated for the as-quenched Fe51Co12Si16B8Mo5P8 amorphous alloy.

Rietveld refinement, morphology and superparamagnetism of nanocrystalline Ni0.70−xCuxZn0.30Fe2O4 spinel ferrite

The crystallographic phase and particle size of Cu2+ substituted Ni-Zn spinel ferrite prepared by nitrate-citrate route was evaluated using XRD and TEM techniques respectively. Rietveld refined XRD patterns revealed the cubic spinel phase with Fd-3m space group. The average particle size estimated from TEM image revealed the nanocrystalline nature which matches well with the crystallite size determined by XRD data. High resolution TEM exhibited the lattice fringe patterns which correspond to cubic spinel structure. The samples were characterized by M-H plots and Mossbauer spectra at room temperature. Magnetization curves exhibited typical superparamagnetic nature of samples which is in good agreement with that of Mossbauer measurements. The obtained coercive field is low which may make these materials suitable for soft magnetic device applications.

A Combinatorial Approach for Assessing the Magnetic Properties of High Entropy Alloys: Role of Cr in AlCoxCr1–xFeNi

A combinatorial assessment of composition‐microstructure‐magnetic property relationships in magnetic high entropy AlCoxCr1‐xFeNi alloy (0 ≤ x ≤ 1) system has been carried out using compositionally graded alloys fabricated via laser additive manufacturing. At one end, the AlCoFeNi composition (x = 1) consisted of equiaxed B2 grains, exhibiting very early stages of phase separation (only compositional partitioning) into Ni–Al rich and Fe–Co rich regions within grains of the B2 phase. At the other extreme, the AlCrFeNi composition (x = 0) exhibited grains with pronounced spinodal decomposition, resulting in a B2 + bcc microstructure with the degree of spinodal decomposition progressively increasing with Cr content in these AlCoxCr1–xFeNi alloys. While the saturation magnetization (Ms) monotonically increases six times from x = 0 to x = 1, the coercivity (Hc) variation is non‐monotonic, increasing seven times from x = 0 to x = 0.4, and subsequently decreasing fourteen times from x = 0.4 to x = 1.0. The magnetic phase transition temperature (Tc) for these alloys also increases monotonically with increasing Co content with a second phase transition exhibited in a certain range of compositions between x = 0.6 to x = 0.8. Such substantial changes in the magnetization behavior and properties of magnetic high entropy systems opens possibilities of tuning these alloys for specific soft or hard magnetic component applications.

Influence of Soft Magnetic Materials Application to Squirrel Cage Induction Motor Design and Performance

Most of the electrical machines design studies found in literature lie on the concept that the design under investigation (and optimization) focuses mainly on the geometrical aspects of the machine and thus takes into account only a certain ferromagnetic material (i.e. iron) for its parts. These studies, give little or no information about the influence of material alternatives on the same (and optimized) design. From a manufacturers’ point of view though, this information is crucial especially nowadays that there are a lot of commercially available materials in the market. In this context, this paper presents the results of a research project in the design stage of an energy efficient three phase squirrel cage induction motor (SCIM), by investigating the effects of several soft magnetic materials (adopted for its stator and/or its rotor parts) on multiple quantities of primary concern such as: efficiency, power factor, output torque, losses, weight and cost. After a brief proposed design procedure, a total of twenty-two different materials from recent manufacturers’ data were examined. Also, the main electromagnetic analysis was performed through commercial analysis software. Simple ranking methods are also proposed here and the results obtained are then thoroughly discussed and commented.

Friction consolidation of gas-atomized Fe[sbnd]Si powders for soft magnetic applications

Soft magnetic materials are often limited in scalability due to conventional processes that do not retain beneficial microstructures, and their associated physical properties, during densification. In this work, friction consolidation (FC) has been studied to fabricate FeSi soft magnetic materials from gas-atomized powder precursors. FeSi powder is consolidated using variable pressure and tool rotation speed in an effort to evaluate this unique densification approach for potential improvements in magnetic properties. FC, due to the high shear deformation involved, is shown to result in uniform gradual grain structure refinement across the consolidated workpiece from the center nearest the tool to the edge. Magnetic properties along different orientations indicate little, if any, textural orientation in the refined grain structure. The effect of annealing on the magnetic properties is evaluated and shown to decrease coercivity. FC processing was able to retain the magnetization of the original gas-atomized powders but further process optimization is needed to reach the optimal coercivity for the soft magnetic materials applications.

Nonstoichiometry and phase stability of Al and Cr substituted Mg ferrite nanoparticles synthesized by citrate method

The spinel ferrite Mg0.7Cr0.3Fe2O4, and Mg0.7Al0.3Fe2O4 were prepared by the citrate technique. All samples were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Micrographs (HRTEM), Energy Dispersive X ray Spectroscopy (EDAX) and Atomic Force Microscope (AFM). XRD confirmed the formation of cubic spinel structure of the investigated samples. The average crystallite sizes were found to be between 24.7 and 27.5nm for Al3+ and Mg2+ respectively. The substitution of Cr3+/Al3+ in place of Mg2+ ion initiates a crystalline anisotropy due to large size mismatch between Cr /Al and Mg2+, which creates strain inside the crystal volume. According to VSM results, by adding Al3+ or Cr3+ ions at the expense of Mg2+, the saturation magnetization increased. The narrow hysteresis loop of the samples indicates that the amount of dissipated energy is small, which is desirable for soft magnetic applications. Magnetic dynamics of the samples were studied by measuring magnetic susceptibility versus temperature at different magnetic fields. The band gap energy, which was calculated from near infrared (NIR) and visible (VIS) reflectance spectra using the Kubelka-Munk function, decreases with increasing the particle size. Furthermore, the band gaps were quite narrow (1.5–1.7eV), hence the investigated samples could act as visible light driven photo catalysts. To sum up the addition of trivalent Al3+, and Cr3+ ions enhanced the optical, magnetic and structure properties of the samples. Mg0.7 Cr0.3Fe2O4 sample will be a better candidate for the optical applications and will also be a guaranteeing hopeful for technological applications.

Spin-exchange interaction between transition metals and metalloids in soft-ferromagnetic metallic glasses

High-performance magnetic materials have immense industrial and scientific importance in wide-ranging electronic, electromechanical, and medical device technologies. Metallic glasses with a fully amorphous structure are particularly suited for advanced soft-magnetic applications. However, fundamental scientific understanding is lacking for the spin-exchange interaction between metal and metalloid atoms, which typically constitute a metallic glass. Using an integrated experimental and molecular dynamics approach, we demonstrate the mechanism of electron interaction between transition metals and metalloids. Spin-exchange interactions were investigated for a Fe–Co metallic glass system of composition [(Co1−xFex)0.75B0.2Si0.05]96Cr4. The saturation magnetization increased with higher Fe concentration, but the trend significantly deviated from simple rule of mixtures. Ab initio molecular dynamics simulation was used to identify the ferromagnetic/anti-ferromagnetic interaction between the transition metals and metalloids. The overlapping band-structure and density of states represent ‘Stoner type’ magnetization for the amorphous alloys in contrast to ‘Heisenberg type’ in crystalline iron. The enhancement of magnetization by increasing iron was attributed to the interaction between Fe 3d and B 2p bands, which was further validated by valence-band study.

ANCORLAM

Abstract AncorLam is a high performance insulated particle material suitable for a variety of soft magnetic applications that require low core losses. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on powder metal forms. Filing Code: CS-194. Producer or source: Hoeganaes Corporation.