Effect Of Magnetic Field Annealing Research Articles

Effect of Magnetic Field Annealing on the Magnetic Properties of Soft-Magnetic Iron–Germanium Alloys

Effect of Magnetic Field Annealing on the Magnetic Properties of Soft-Magnetic Iron–Germanium Alloys

Effects of magnetic field annealing on the hard magnetic properties of milled Nd-Fe-B powders

In this study, we report the effect of magnetic field annealing (MA) in relieving the stress induced during the milling of Nd-Fe-B sintered magnets. The effect of MA processing parameters and particle size on the magnetic properties were investigated. Based on the results, magnetic field annealing is more effective in improving the magnetic properties of larger size particles, compared to finer particles. Our computational study on the role of particle surface defects in bimodal particle distribution agrees with results obtained experimentally. Magnetic field annealed powder has been successfully used to develop 4.6 g.cm−3 density bonded magnets with 75 vol% of magnetic powder and polyamide 12 (nylon 12) polymer binder resulting in 11.3 MGOe energy product.

Effect of magnetic field annealing on magnetic properties and corrosion resistance of MnBi alloy

Herein, MnBi alloys are prepared using melt spinning and magnetic-field annealing techniques, and the effects of magnetic-field annealing on the microstructure, magnetic properties, magnetisation behaviour, and corrosion resistance of MnBi are systematically investigated. The results show that the saturation magnetisation (Ms) of the Mn55Bi45 ribbons increases with increasing magnetic field annealing temperature and time. Annealing above Curie temperature (Tc) enhances the intrinsic coercivity (Hcj) of the MnBi alloy. Moreover, Mn55Bi45 ribbons with a (BH)max of 2.15 MGOe at room temperature are successfully fabricated after annealing at 673 K for 20 min. The first-order reversal curve (FORC) demonstrate that the Mn55Bi45 ribbons after magnetic-field annealing exhibits weaker exchange coupling compared with the Mn55Bi45 ribbons after nonmagnetic-field annealing. Additionally, the corrosion rate of the Mn55Bi45 ribbons after magnetic-field annealing is lower than that of the Mn55Bi45 ribbons after nonmagnetic-field annealing. Finally, the changes in the grain size and content of the MnBi phase are investigated.

Non-Aqueous electro-deposition of novel one-dimensional Sm2Co17 nanostructures and magnetic field annealing effect on structural and magnetic properties

Through a versatile and quite economical technique of DC electro-deposition, Sm2Co17 nanowires (NWs) have been fabricated into the nanochannels of anodic aluminum oxide (AAO) templates by using non-aqueous electrolyte. The average diameter and length of NWs are 80 nm and 3 µm respectively. The structural and magnetic properties of NWs have been investigated before and after magnetic field (MF) annealing with magnetic field strength of 1 T applied parallel to the NWs axis at temperature of 300 °C. SEM and TEM have been employed to observe the morphology of NWs after partial and full etching respectively. Deposition of SmCo alloy has been confirmed through EDX analysis whereas XRD peaks shows hexagonal closed packed (hcp-P63/mmc) as the dominant phase with (203) preferred orientation. After MF annealing the crystallinity got improved as manifested by the increase in peak sharpness. Furthermore, after the said field assisted heat treatment the magnetic parameters including coercivity (Hc) from 91 to 527 Oe for θ = 0°, from 101 to 151 Oe for θ = 90° and squareness (SQ) from 0.040 to 0.16 for θ = 0°, from 0.037 to 0.032 for θ = 90° have been observed through VSM. A switching of magnetization reversal mechanism from curling to coherent rotation has been observed after MF annealing due to the stronger inter-wire coupling which leads to parallel alignment of magnetic moments of adjacent NWs. Temperature dependent study has been carried out employing PPMS manifesting gradual increase in Hc from 67 to 440 Oe, Ms from 5.4 × 10−3 to 6.1 × 10−3 emu and SQ from 0.19 to 0.25 with the decrease in temperature up to 5 K.

Effect of Magnetic Field Annealing on Magnetic Properties of Iron–Gallium Alloys

The concentration dependence of magnetic properties of iron alloys with 3–25% of gallium is studied. It was shown that the saturation induction monotonically decreases with increasing gallium content, while the coercivity exhibits a step increase with a step from 85 to 135 A/m between 12 and 15 at % Ga. The effect of magnetic field annealing (MFA) on the behavior of the residual induction and coercive force in alloy samples containing from 3 to 18 at % Ga is studied. As a result of MFA, magnetic anisotropy is induced in the alloy: magnetic hysteresis loops become narrower, the residual induction increases, and the coercivity decreases. The MFA efficiency reaches a maximum at a Ga content of 15–18 at %. The features of the structure state of iron–gallium alloys and their role in the formation of magnetic properties during annealing in a dc magnetic field are discussed.

Magnetic field annealing effect and superparamagnetic contributions in one-dimensional CoPt nanostructures

A low cost versatile electrochemical method has been employed to synthesize highly ordered CoPt nanowires (NWs) in anodic aluminum oxide (AAO) templates with average pore diameter of about 100 nm. The structural properties of as deposited NWs have been studied through XRD analysis showing face centered cubic (fcc) as the dominant phase of CoPt NWs. Magnetic properties at room temperature and lower temperature has been investigated with applied field parallel and perpendicular to NWs axis. The easy magnetization axis is aligned perpendicular to NWs owing to the strong magnetostatic interactions among the NWs due to smaller interwire distance (∼15 nm). Furthermore, the as deposited arrays of NWs have been annealed for 2 h at 300 °C in the presence of 1 T magnetic field applied in the direction perpendicular to NWs axis. Magnetic field annealing gives improved structural and magnetic behavior of these one-dimensional (1D) nanostructures resulting improved crystallinity and increased values of coercivity (Hc) and remnant squareness (SQ). Superparamagnetic contributions at lower temperature due to presence of fine nanoparticles in blocking state play important role and leads to enhanced magnetic behavior of CoPt NWs.

Effect of magnetic field annealing on the magneto-elastic properties of nanocrystalline NiFe2O4

The effect of magnetic-field annealing on the strain sensitivity (q) and saturation magnetostriction (λs) of NiFe2O4 nanoparticles synthesized by citrate-gel method was investigated. The use of field-annealing resulted in improved magnetoelastic properties at the expense of coercivity. A maximum λs of −40ppm at 2kOe, associated with q value of −3.3ppm/Oe at 5Oe was achieved in the field-annealed NiFe2O4.

Effect of Magnetic Field Annealing on Microstructure and Magnetic Properties of FeCuNbSiB Nanocrystalline Magnetic Core with High Inductance

Effect of Magnetic Field Annealing on Microstructure and Magnetic Properties of FeCuNbSiB Nanocrystalline Magnetic Core with High Inductance

The evolution of recrystallized texture of cold-rolled pure copper annealed with a magnetic field in the transverse direction

In this paper, the effect of magnetic field annealing was investigated on the evolution of recrystallized texture of a cold-rolled pure copper sheet. During magnetic field annealing the transverse direction of the specimen was set to be parallel to the magnetic field. It was found, although, altering the orientation of the specimen to the magnetic field direction during annealing does not change the type of the recrystallized texture component, the intensity of cube texture in the specimen with field is higher than that without field.

Annealing Effects on Magnetic Properties of Co/Cu Multilayered Nanowires

Co/Cu nanowires were fabricated by electrodeposition using anodic alumina templates, with 100nm diameter nanopores. The thickness of Co and Cu layer was about 45nm and 5nm, respectively. The magnetic properties have been studied before and after simple and magnetic field annealing. For simple annealing an increase in coercivity and squareness along easy axis of magnetization has been observed. For comparison, the magnetic field annealing effect on magnetic properties has been studied by using fast and slow temperature variations. The corresponding change in saturation magnetization, coercivity, remanent squareness, and the shape of hysteresis loops has been investigated.

Magnetic Field Annealing Effects on Magnetic Properties of Electrodeposited Co/Cu Multilayered Nanowires

Co/Cu nanowires were fabricated by electrodeposition using anodic alumina templates, with 100 nm diameter nanopores. The thickness of Co and Cu layer was about 45 and 5 nm, respectively. The magnetic properties of multilayered nanowires have been studied before and after simple and magnetic field (MF) annealing. For simple annealing, an increase in coercivity and squareness (SQ) along easy axis of magnetization has been observed. Magnetic field annealing has been done under MF of 1 T. For comparison, the MF annealing effect on magnetic properties has been studied using fast and slow temperature variations. The corresponding change in saturation magnetization, coercivity, remanent SQ, and the shape of hysteresis loops has been investigated. The coercivity Hc decreases in case of MF annealing with fast temperature variation, whereas it increases in case of MF annealing with slow temperature variation, as compared with as deposited. The enhanced magnetic anisotropy has been observed by slow MF annealing (SMFA), whereas magnetic anisotropy attenuated a little by fast MF annealing. Annealing without MF has also shown the enhanced magnetic anisotropy. SMFA and annealing without MF is likely to improve the interface of Co/Cu.

Post magnetic field annealing effect on magnetic and structural properties of Co80Pt20 nanowires and nanotubes fabricated by electrochemical method

Highly ordered Co80Pt20 nanowires (NWs) and nanotubes (NTs) have been synthesized by low cost DC electrochemical deposition method with constant stirring during the fabrication process in anodic aluminum oxide nano-templates with average pore diameter of about 200 nm. The structural and magnetic properties of nanostructures have been investigated before and after simple and magnetic field annealing. Magnetic field of 1 T has been applied during annealing process in the direction perpendicular to NWs and NTs axis. X-Ray Diffraction analysis shows face centered cubic (fcc) as the dominant phase for Co80Pt20 NWs and post annealing led to better crystallinity with retained fcc phase. Furthermore, magnetic properties, including saturation magnetization (Ms), squareness ratio (Mr/Ms), and coercivity (Hc), have been investigated as a function of annealing temperature by Vibrating Sample Magnetometer.

Effect of magnetic field annealing and size on the giant magnetoimpedance in micro-patterned Co-based ribbon with a meander structure

Micro-patterned Co-based amorphous ribbons (Metglas® 2714A) with a meander structure are fabricated by MEMS technology and the giant magnetoimpedance (GMI) effects are measured at different magnetic fields and frequencies. The effect of magnetic field annealing and size (line width and line length) on the GMI effect is investigated. It is found that the GMI effect in the transverse magnetic field-annealed state is larger than that in longitudinal magnetic field-annealed state and nonfield-annealed state. The maximum GMI effect increases from 82 % for the sample with 5 mm length to 150 % for the sample with 10 mm length, and the maximum GMI effect decreases with the increase of the line width.

Effects of Magnetic-Field Annealing on the Morphology and Magnetic Properties of La0.7Sr0.3MnO3 Film

La0.7Sr0.3MnO3 (LSMO) films were prepared by the chemical solution deposition method with an external magnetic-field (Hext=5 kOe) annealing process. Structural and magnetic properties were systematically investigated. X-ray diffraction results show that both LSMO films are single-phase. The results of field-emission scanning electronic microscopy show that the mean grain size of the film annealed under Hext=5 kOe are about 2.5 times larger than that of the annealed film under Hext=0 kOe. The enhanced magnetic properties are explained reasonably by the magnetic-field annealing.

Soft magnetic thin films: influence of annealing on magnetic properties

Soft magnetic materials are currently used in a variety of applications in electrical machines, sensors and elements of devices. If prepared in thin film form, they can be applied to micro- and nano-patterned devices. However, with respect to ribbons and bulk materials, thin films of the same composition usually display worse soft magnetic properties, thus requiring suitable solutions to restore high permeability and low coercivity. In this review, the magnetic properties of thin films prepared by sputtering are presented. Several compositions of soft magnetic materials are investigated, including Co-Fe-Si-B, Fe-Cu-Nb-Si-B, Fe-Si-B, Fe-Co-Nb-Si-P-B, Fe-Zr-Nb-Cu-B. Their amorphous-to-crystallization processes are studied by means of furnace annealing and Joule heating. Hysteresis loops and magnetic domain imaging, together with structural techniques, are used to follow the effects of annealing, which include stress relaxation and crystallization. The effects of magnetic field annealing are investigated and discussed.

Effects of magnetic annealing on structure and multiferroic properties of pure and dysprosium substituted BiFeO3

In this work, the effects of magnetic annealing on crystal structure and multiferroic properties of BiFeO3 and Bi0.85Dy0.15FeO3 have been investigated. It is found that the X-ray diffraction patterns of pure BiFeO3 samples are obviously broadened after magnetic annealing, whereas those of Bi0.85Dy0.15FeO3 samples are almost unchanged. Magnetic field annealing did not affect the magnetic properties of these two kinds of samples much. However, ferroelectric properties of the two materials exhibited different behaviors after magnetic field annealing. For pure BiFeO3 samples, the remnant polarizations (Pr) are suppressed; in contrast, for Bi0.85Dy0.15FeO3 samples, Pr is greatly enhanced. Possible mechanisms for the effects of magnetic field annealing have been discussed.

Effects of Magnetic Field Annealing on Carburizing in Pure Iron

AbstractEffects of magnetic field annealing on carburizing behavior in pure iron in the γ‐Fe temperature region were investigated. Specimens were subjected to isothermal annealing at 930 °C for 25 min with a heating rate of 5 °C /min, and then cooled in the furnace. A magnetic field with different intensity was applied during the whole heating, isothermal holding and cooling processes. The results showed that the magnetic field annealing obviously hindered the carburization in γ‐Fe in the direction parallel and anti‐parallel to the magnetic field direction and this effect increased with the enhancement of the magnetic field intensity.

Effects of layering and magnetic annealing on the texture of CoPt films

The effect of magnetic field annealing of magnetron sputtered CoPt alloy films and Co/Pt bilayers on the crystallographic texture of the obtained chemically ordered (L1 0) CoPt films is presented. In CoPt alloy films the main effect of the magnetic field is to suppress (1 1 1) growth in the early stages of L1 0 formation whereas the development of (0 0 1) versus (1 0 0) texture is related to chemical ordering strain. A higher degree of (0 0 1) texture is obtained by magnetically annealing Co/Pt bilayers since the initial (1 1 1) texture in the as-sputtered films is avoided and Co–Pt alloying occurs in the presence of the magnetic field.

Fe48Co52 Alloy Nanowire Arrays: Effects of Magnetic Field Annealing

The effects of magnetic field annealing on the properties of Fe48Co52 alloy nanowire arrays with various interwire distances (Di = 3060 nm) and wire diameters (Dw = 2246 nm) were investigated in detail. It was found that the array's best annealing temperature and crystalline structure did not show any apparent dependence on the treatment of applying a 3 kOe magnetic field along the wire during the annealing process. For arrays with small Dw or with large Di, the treatment of magnetic field annealing also had no obvious influence on their magnetic performances. However, such a magnetic field annealing constrained the shift of the easy magnetization direction and improved the coercivity and the squareness obviously for arrays with large Dw or with small Di. The difference in the intensity of the effective anisotropic field within the arrays was believed to be responsible for this different variation of the array's magnetic properties after magnetic field annealing.

Effect of Magnetic Field Annealing Upon Co-Rich Nanowires

The magnetic field (MF) annealing of dc electrodeposited ferromagnetic nanowire arrays of compositions Co94Fe06 , Co91Fe07B2 was done in the direction of their easy axis of magnetization (in plane) at 2650 C under 800 Oe applied magnetic field for 2 h. An induced magnetic anisotropy (MA) and a large increase in saturation magnetization (Ms) were manifested by the changes in hysteresis loops of the nanowire samples before and after the annealing process. The structural changes were investigated using X-ray diffraction and transmission electron microscopy (TEM). The shape of nanowires, the predicted natural texture with c-axis in the plane of membrane (because of high concentration of cobalt) and diffusional pair ordering of unlike atoms along the direction of external applied field were thought to be the causes of induced MA. The reannealing of samples in absence of MF at 400degC and 600degC produced no significant changes in hysteresis loops instead of removing the MA but with evolution of crystalline phase in both the samples. Therefore, the shape of nanowire was concluded to play the major role in persistence of induced MA in nanowire samples after high temperature annealing