FeCuNbSiB Ribbons Research Articles

Effect of a DC transverse magnetic field on the magnetization dynamics in FeCuNbSiB ribbons and derived nanostructured powder cores

The paper aims to give a comprehensive account of DC transverse bias magnetic field influence on the dynamic magnetization processes in Fe73Cu1Nb3Si16B7 soft magnetic ribbons and nanostructured powder cores based on ribbon precursor. These materials were extensively investigated using an approach of impedance spectroscopy from the viewpoint of complex permeability spectra, which offer the indirect insight into magnetization mechanisms and their frequency relaxation. In order to analyze the dynamic nature of domain wall magnetization mechanism, we carried out complex permeability measurements under combined influence of three independent variables, i.e. magnetizing frequency, various driving AC and DC bias magnetic fields. From this ample matrix of results, it has been found that the DC bias smaller than some critical field can increase the real part of complex permeability in the case of as-quenched and annealed ribbon. Nonetheless, the higher fields play a role of additional anisotropy and consequently domain wall damping mechanism. For nanocrystalline compacted powder cores, only the damping influence of DC transverse field was observed. The results are compared in detail and possible mechanisms of domain wall movement damping are proposed and discussed.

Self-biased magnetoelectric coupling characteristics of three-phase composite transducers with nanocrystallin soft magnetic alloy

This paper reports the self-biased magnetoelectric (ME) effects in composites consisting of high-permeability Fe-based nanocrystalline soft magnetic alloy Fe73.5Cu1Nb3Si13.5B9 (FeCuNbSiB), pure nickel (Ni) and piezoelectric lead zirconate titanate (PZT). The FeCuNbSiB ribbons are fabricated on traditional laminates Ni/PZT/Ni through two modes: the attached mode (F–NPN–F) and the laminated mode (F/NPN/F). The F–NPN–F composite sufficiently reveals that the high-permeability FeCuNbSiB ribbons concentrate more magnetic flux in magnetostrictive Ni, which results in the self-biased ME effects of F–NPN–F. For the F/NPN/F composite, the FeCuNbSiB acts as the dynamic driver to enhance the effective piezomagnetic coefficient of Ni. The giant self-biased ME effects of F/NPN/F are because of the internal magnetic field between Ni and FeCuNbSiB due to their different magnetic characteristics. The influences of the numbers of FeCuNbSiB layers (L) on the resonant ME voltage coefficients (α ME,r ) for F–NPN–F and F/NPN/F composites are investigated in detail. The experiments demonstrate that the maximum α ME,r at zero-biased field is 80 V/cm Oe for F–NPN–F with L = 2, and 85 V/cm Oe for F/NPN/F with L = 4. This paper demonstrates that these two ME composites are suitable for achieving zero-biased ME transducers, power-free magnetic field sensors and energy harvesters.

Investigation of magnetostrictive/piezoelectric multilayer composite with a giant zero-biased magnetoelectric effect

In this paper, we investigate the resonance magnetoelectric (ME) effect in the middle supported multilayer composites consisting of high-permeability Fe-based nanocrystalline soft magnetic alloy Fe73.5Cu1Nb3Si13.5B9 (FeCuNbSiB), Nickel (Ni), and piezoelectric Pb(Zr1−x Ti x )O3 (PZT). The coupling effect between positive magnetostrictive FeCuNbSiB and negative magnetostrictive Ni results in the build-in magnetic bias due to their different magnetic permeability and coercivity. As a result, a giant resonance ME voltage coefficient (α ME,r ) at zero DC magnetic bias field (H dc) and multi-peaks of α ME,r for FeCuNbSiB/Ni/PZT/Ni/FeCuNbSiB composite are observed. The experimental results show that the giant zero-biased α ME,r strongly depends on the thickness of FeCuNbSiB ribbon. The maximum zero-biased α ME,r is up to 86 V/cm Oe for FeCuNbSiB/Ni/PZT/Ni/FeCuNbSiB with four-layer FeCuNbSiB ribbons, which is ∼500 times higher than that of the previously reported NKNLS-NZF/Ni/NKNLS-NZF trilayer composite. Compared with the peak α ME,r and the optimum H dc of Ni/PZT/Ni composite, the largest peak α ME,r of FeCuNbSiB/Ni/PZT/Ni/FeCuNbSiB composite with four-layer FeCuNbSiB ribbons increases ∼185 %, and the optimum H dc decreases ∼300 Oe, respectively. Based on the nonlinear magnetostrictive constitutive relation and the magnetoelectric equivalent circuit, a theoretical model of α ME,r versus H dc is built under free boundary conditions. Calculated zero-biased α ME,r and α ME,r versus H dc are in good agreement with the experimental data. This laminate composite shows promising applications for high-sensitivity power-free magnetic field sensors, zero-biased ME transducers and small-size energy harvesters.

The Magnetic Properties of FeCuNbSiB Flake Particles Prepared by Milling the Annealed Ribbons

The amorphous FeCuNbSiB ribbons were first annealed at the temperature of 450 oC and 540 oC, respectively. Then, these annealed ribbons were milled into flake particles with the same condition. The different annealing temperature made the ribbons have the different crystallinities, which caused the milled particles have the different structures, morphologies, and magnetic properties. As for the flake particles by milling the ribbons annealed at 540 oC, they had higher crystallinity, smaller size, lower coercivity, and higher complex permeability compared with those by milling the annealed ribbons at 450 oC.

Enhanced magnetoelectric effects in laminate composites ofTerfenol-D/Pb(Zr, TiO)3 with high-permeability FeCuNbSiB ribbon

The enhancement of resonant magnetoelectric (ME) effectsis reported in the structure consisting of a piezoelectric PZT(Pb(Zr1 − xTix)O3) plate, a magnetostrictiveTerfenol-D (Tb1 − xDyxFe2 − y) plate, and multiple high-permeability FeCuNbSiB(Fe73.5Cu1Nb3Si13.5B9) ribbon plates. The FeCuNbSiB ribbon acts as the dynamic driver to increase the effectivepiezomagnetic coefficient of the Terfenol-D and enhances the effective mechanical quality factor (Qm) of the laminateowing to its high Qm, consequently resulting in the increase of the dynamic strain coefficient of Terfenol-D andthe resonant ME voltage coefficient (MEVC). The experimental results show that theTerfenol-D/PZT/FeCuNbSiB (MPF) composite with double-layer FeCuNbSiB ribbons canachieve a higher resonant MEVC than that with single-layer or other multilayer ribbons,which is 2–3 times as high as that of the Terfenol-D/PZT(MP) composite under a lowHdc. In addition, the ME voltage strongly depends onHdc, the maximumvalue of dVME/dHdc achieves 125.9 mV Oe − 1. The MPF laminate has potential for highly sensitive dc magnetic field sensing.

Sensitivity enhancement of longitudinally driven giant magnetoimpedance magnetic sensor using magnetoelastic resonance

The enhancement of longitudinally driven giant magnetoimpedance (LDGMI) effect in FeCuNbSiB ribbons was investigated utilizing magnetoelastic resonance. A maximum LDGMI ratio of the order of 10,000% was obtained for the ribbon annealed at 480 °C under optimum driving current frequency and driving current intensity. The dependences of enhancement magnitude on magnetoelastic coupling coefficient k 33 and quality factor Q were analyzed in detail. It was found that high k 33 and Q were favorable to enhance giant magnetoimpedance effect. The complex permeability of ribbon core was calculated, and the relationship between them and LDGMI enhancement behavior was also discussed. Additionally, a simple magnetic sensor based on this effect was developed. Its output sensitivity and stability were studied as well.

Exchange bias behavior of nanocrystalline FeCuNbSiB ribbons

Exchange bias phenomena of nanocrystalline FeCuNbSiB ribbons have been investigated at room temperature. It was found that the rougher surface of ribbons annealed in longitudinal field played a main role in bringing the bias behavior in our ribbons. The topography of ribbon surfaces and the configuration of magnetic domains were specially observed in order to make clear the dependence of bias behavior on the induced magnetic anisotropy. A simple phenomenological explanation was also put forward to promote the comprehension of loop shift in ribbons and its possibility of potential applications.

Design of a double core linear magnetometer based on asymmetric magnetoimpedance effect in nanostructured Finemet ribbons

Abstract The techniques used to produce magnetic sensors encompass many aspects of physics and electronics and are going to develop with each passing year. In this paper, we introduce a double core giant magnetoimpedance sensor. The sensing elements are provided by heat treating the FeCuNbSiB (Finemet) ribbons at 560 °C for 1 h to achieve a high magnetic permeability associated with the nanostructured state. Sensor cores are exposed to a dc current bias in order to provide asymmetric giant magnetoimpedance (AGMI) behavior. The sensor detects both direction and amplitude of the magnetic field with a sensibility of 2 mV/Oe.

Giant Magnetoimpedance in as Quenched Fe Based Nanocrystalline Ribbons

FeCuNbSiB and FeZrBCu nanocrystalline ribbons can be obtained directly through the melt- spinning technique without additional annealing processes. The giant magnetoimpedance can be observed in FeCuNbSiB and FeZrBCu as quenched ribbons. The addition of Cu improves the nano-crystallization of a-Fe(Si) or a-Fe phase and reduces the grain size in FeCuNbSiB and FeZrBCu as quenched ribbons, which enhances the magnetoimpedance via increasing the variation of permeability under fields. The present experimental results reveal a novel route to fabricate the Fe based nanocrystalline soft magnetic materials with giant magnetoimpedance effect.

Permeability spectra of neutron-irradiated and annealed amorphous FeCuNbSiB ribbons

The neutron irradiation effects of soft magnetic properties in the as-quenched and the annealed amorphous Fe 73.5Cu 1Nb 3Si 13.5B 9 alloys were studied by complex permeability spectra measurement. The annealing at 823 K caused the decrease of permeability from irreversible domain wall motion but increase the permeability from reversible magnetization, compared to the as-quenched sample. The neutron irradiation in the as-quenched sample increases the permeability from both irreversible and reversible magnetization processes. The neutron irradiation in the annealed sample showed the increase of permeability from irreversible domain wall motion, but decrease of permeability from reversible magnetization.

Nanostructured metallic cores with extremely low loss and controlled permeability

Magnetic anisotropy perpendicular to the ribbon axis was induced in nanocrystalline FeCuNbSiB ribbons by crystallization under tensile stress, and the relative permeability of the ribbon was approximately 250. Toroidal cores for a choke coil were prepared from the ribbons. The magnetic loss decreased with increasing the core diameter and it was found that deterioration of magnetic properties due to formation of a toroidal core was suppressed by making the core diameter larger than the critical diameter determined from the values of magnetostriction and induced anisotropy. As a result, toroidal cores-with extremely low loss were achieved. The permeability of the cores developed was kept constant up to 1 MHz and their magnetic loss was much smaller than the loss values reported previously for nanostructured and amorphous cores with low permeability. The measured magnetic loss agreed with the calculated classical eddy current loss. In addition, the permeability and magnetic loss were kept constant up to the dc bias field, being three times higher than that applicable to a ferrite cut core with the same permeability value.

DC magnetic shielding effects of soft composite sheets

Three composite sheets are made from CoFeNiVSiB, FeCuNbSiB and FeSiB amorphous ribbons. The shielding factors increase with the layers of the composite sheets. FeSiB composite sheets are effective on magnetic shielding at higher applied magnetic field, while FeCuNbSiB and CoFeNiVSiB composite sheets are applicable in lower field.

New magneto-optical effects for investigation of near-surface micro-magnetic structure of FeCuNbSiB amorphous ribbons

The peculiarities of new magneto-optical intensity effects that we discovered are described. The results on the investigation of near-surface micro-magnetic structure (MMS) of the as-cast and annealed at 550°C for 1 h FeCuNbSiB ribbons are presented. The measurements were performed by means of the transverse Kerr effect (TKE) and new magneto-optical effects. It was established that the local magnetic properties of the studied ribbons depend on their structure.

X‐Ray Study of Nanocrystalline Ribbons FeCuNbSiB Subjected to Thermomechanical and Thermomagnetic Treatments

An attempt to discover the structure peculiarities giving rise to induced magnetic anisotropy in a finemet subjected to thermomechanical or thermomagnetic treatment has been undertaken. Grain size, internal stresses and texture in FeCuNbSiB ribbons were investigated. It was concluded that the induced magnetic anisotropy must have another reason e.g., directional ordering of Si atoms.

Frequency dependence of the magnetoimpedance in nanocrystalline FeCuNbSiB with high transverse stress-induced magnetic anisotropy

Stress-annealed nanocrystalline FeCuNbSiB ribbons show correlation between induced magnetic anisotropy and magnetoimpedance. Two types of crystallization process were used in order to induce a transverse magnetic anisotropy: the first one was performed submitting the original amorphous samples to an applied tensile stress of /spl sigma/=150 MPa. In the second one, samples are nanocrystallised in a first stage and submitted to stress annealing at /spl sigma/=290 MPa afterwards. The maximum of the magnetoimpedance can be obtained for dc fields larger than the anisotropy field of the sample or close to the irreversibility field. This behavior can be explained based in the simultaneous switching of two different magnetization processes taking place in the samples with high transverse magnetic anisotropy.

Properties of micromagnetic structures in amorphous FeCuNbSiB alloys

Results are presented of a magnetooptic investigation of the surface micromagnetic structure of FeCuNbSiB ribbons in the initial state and after annealing at 550 °C for 1 h. In the initial state the samples were amorphous, whereas after annealing they exhibited a nanocrystalline structure with typical grain sizes of 10–12 nm. Dispersion of the magnetic anisotropy was observed in the samples studied; this was responsible for the nonuniformity of their local magnetic properties. It was found that the linear dimension of the magnetic inhomogeneities in the initial and annealed samples was 120–150 and 50–70 μm, respectively.

Magneto-optical investigation of near-surface micro-magnetic structure of FeNbCuSiB alloys

The results on the investigation of near-surface micro-magnetic structure of the as-cast and annealed at 550°C for 1hr FeCuNbSiB ribbons are presented. The measurements were performed by using of the magneto-optical micro-magnetometer having the spatial resolution up to ∼0.3μm. The as-cast samples were amorphous and the annealed samples had nanocrystalline structure with typical grain sizes of 10-12 nm. The dispersion of magnetic anisotropy was discovered in the studied samples. As result, their local magnetic properties were inhomogeneous. The linear size of the magnetic inhomogeneities in the as-cast and annealed samples was equal to ∼ 120-150 and ∼ 50-70 μm, respectively. It was established that in the annealed samples the local initial magnetic permeability increases and the coercivity decreases (up to 10 times) with respect to those of the ascast samples.

Influence of etching of the surface on the magnetic properties of amorphous and nanocrystalline Fe73.5Cu1Nb3Si15.5B7 ribbon

Here we present the results for the influence of etching of the surfaces of the amorphous Fe 73.5 Cu 1 Nb 3 Si 15.5 B 7 ribbon on its magnetic properties in amorphous state and states obtained by successive annealing for one hour at several temperatures T a ≤ 450°C. We discuss the changes in the domain structure, anisotropy and domain wall (DW) pinning in terms of the corresponding changes in the average angle between the domain magnetizations and ribbon axis, coercive field H c , remanent magnetization M r and maximum permeability μ max . The measurements show rather weak effects of etching on the magnetization processes and DW pinning in the amorphous state (small initial decrease of H c ). Results for the successively annealed sample show that etching does not improve properties of the nanocrystallized FeCuNbSiB ribbons.

Sensitive field- and frequency-dependent magnetoimpedance in nanocrystalline Fe 73.5CuNb 3Si 13.5B 9 ribbons

The magnetoimpedance spectra (0 ≤ f ≤ 3 MHz) of amorphous and of nanocrystallized (550 °C annealing for 0.5–18 h) FeCuNbSiB ribbons were measured at room temperature using a commercial impedance analyzer as a function of applied magnetic field up to 75 Oe. The magnetoimpedance (MI), Z( f, H), shows strong dependence on frequency of the drive, ac current and magnetic field. For all the samples, the MI ratio ΔZ/Z = (Z(H max) − Z(0))/Z(H max) first increases rapidly with frequency ( f) and reaches a maximum at about 300–500 kHz, then decreases with F f. The maximum value of the MI ratio ΔZ/Z, −227%, is obtained in the sample annealed at 550 °C for 3 h with ac current at 300 kHz. At higher frequency, a peak in field dependence of the MI ratio ( Z(H) − Z(0))/Z(H max) was obtained for nanocrystalline samples, but not for as-quenched amorphous connterparts. The field dependence of effective permeability has been shown to be responsible for their MI effects.

Compositional evolution and magnetic properties of nanocrystalline Fe73.5Cu1Nb3Si13.5B9

Melt-spun FeCuNbSiB ribbons were annealed at 540–550 °C for various times (≤1 h). The development of a nanocrystalline structure was investigated by means of Mössbauer spectroscopy. From measured hyperfine fields and intensities the crystalline phase was inferred to be pure Fe1−xSix, with x=0.18 after 1 h annealing. The residual amorphous volume fraction was determined to be ≂50%. With help of these results it has been possible to evaluate the amorphous contribution to magnetostriction in the nanocrystalline state. The development of a nanocrystalline structure was found to play a role in the main mechanisms of magnetic disaccommodation.