Initial Magnetization Curve Research Articles

Characteristics of Electric Motor according to the Weld-laminated Core and the Bond-laminated Core

This paper examines the differences between the magnetic and mechanical characteristics of the motor core depending on the lamination method (weld and bond lamination) and analyzes the effects of these differences on the motor performance and vibration using analytical methods and tests. First, to analyze the magnetic and mechanical properties of iron cores according to lamination method, the initial magnetization curve and iron loss were measured, and the natural frequencies and damping ratios were identified through a modal test. Next, no-load and blocked-rotor tests of an induction motor were performed to determine the difference in the performance of the motor according to the lamination method. At this time, the loss occurring in the motor was divided into the primary copper loss, secondary copper loss, iron loss, and mechanical loss. Finally, the output, efficiency, and vibration of the motor were measured to analyze the effects of the magnetic and mechanical characteristics on the motor performance.

Magnetic and magnetoelectric properties of Y-type Ba0.6Sr1.4Zn2Fe12O22 hexaferrite single crystal

Magnetic and magnetoelectric properties of Y-type hexaferrite single crystal Ba0.6Sr1.4Zn2Fe12O22 were investigated using vibrating sample magnetometer and ferromagnetic resonance (FMR) techniques. It was found that this compound orders magnetically below 400 K and magnetization exhibits a sharp peak at 331 K, which corresponds to magnetic transition from collinear ferrimagnetic phase to a proper screw spin phase with decreasing temperature. Magnetic hysteresis measurements showed stepwise behavior of initial magnetization curve due to sequential metamagnetic transitions with increasing magnetic field. Using novel and sensitive method of electrically modulated FMR it was shown that this Y-type hexaferrite has significant magnetoelectric coupling, which was determined quantitatively at room temperature. Obtained results show that Y-type hexaferrite Ba0.6Sr1.4Zn2Fe12O22 has a rare combination of magnetoelectric coupling and large magnetization at room temperature, which is important for applications in magnetoelectric devices.

Investigation of magnetization reversal processes in Sm(Co, Fe, Cu, Zr)7.5 magnets

The processes of magnetization reversal in isotropic and anisotropic commercial permanent magnets Sm(Co, Fe, Cu, Zr)7.5 were investigated. Features of magnetization reversal process in both textured and isotropic magnets were analyzed with δM(H) plots, magnetic susceptibility and initial magnetization curves. The magnetization reversal of Sm(Co, Fe, Cu, Zr)7.5 magnets is more complicated than that described in the coercivity model based on the domain walls pinning.

Effect of grain boundary on magnetization behaviors in 2:17 type SmCo magnet

Abstract The effect of grain boundary area on the magnetization behaviors in Sm25Co48Fe20Cu5Zr2 magnet was investigated. Grain boundary area with deficiency of Cu and incomplete cellular microstructure was clearly observed. In-situ Kerr observation revealed that the magnetization reversals firstly occurred in the grain boundary areas and then propagated into the interiors of grain. The grain boundary areas with weakened pinning force of magnetic domain walls could undermine the coercivity and induce inferior squareness of the magnet. The investigation using Fresnel LTEM demonstrated that the grain boundary area was magnetized more easily than the grain interior, which agreed with the multi-stage phenomenon of the initial magnetization curve of the magnet.

Magnetic Properties of Polycrystalline Compounds Cu0.64Mn0.86[Fe(CN)6]·7.2H2O and Cu0.84Mn0.66[Fe(CN)6]·7.1H2O

In this work, polycrystalline powder samples of Cu0.64Mn0.86[Fe(CN)6]·7.2H2O and Cu0.84Mn0.66[Fe(CN)6]·7.1 H2O have been synthesized by a coprecipitation method. The lattice parameter a is 10.053(8) A and 10.083 A for Cu0.64Mn0.86[Fe(CN)6]·7.2H2O and Cu0.84Mn0.66[Fe(CN)6]·7.1H2O, respectively. When the temperature reaches to 5 K, the magnetization is 7.262 emu/g and 0.142 emu/g for Cu0.64Mn0.86[Fe(CN)6]·7.2H2O and Cu0.84Mn0.66[Fe(CN)6]·7.1H2O, respectively. The coercive field and the remanent magnetization of Cu0.64Mn0.86[Fe(CN)6]·7.2H2O are 1204 Oe and 0.382 μB/fu, respectively. The coercive field and the remanent magnetization of Cu0.84Mn0.66[Fe(CN)6]·7.1H2O are 833 Oe and 0.681 μB/fu, respectively. In the initial magnetization curve, under the external magnetic field of 7 T, the magnetization of Cu0.64Mn0.86[Fe(CN)6]·7.2H2O and Cu0.84Mn0.66[Fe(CN)6]·7.1H2O is 2.13 μB/fu and 2.44 μB/fu, respectively. The difference between the calculated magnetic moment and the theoretical magnetic moment is quite large, which may be due to spin frustration.

Identification of Magnetization Characteristics of Material From Measured Inductance Data

This paper introduces a novel identification method of the magnetization properties of the core material for an inductor from measured inductance data. The proposed method allows us to obtain the magnetic hysteresis characteristics without a special measurement instrument for material $B - H$ properties. The proposed method determines the parameters included in the distribution function for the Preisach model from the measured $L - I$ characteristics. It is shown that the identified initial magnetization curve and the minor loops are in good agreement with the original $B - H$ curves. The uniqueness for the identification problem is numerically verified.

The Structure and Magnetic Properties of Bulk Amorphous FeCoYB Alloys

In this paper the results of the structure and magnetic studies for bulk amorphous Fe62Co10Y8B20 and Fe64Co10Y6B20 alloys were presented. For the structural investigation was performed by X-ray diffractometry. It was found that investigated samples were amorphous in the as-cast state. Using a vibrating sample magnetometer (VSM) the magnetisation within magnetic fields ranging from 0 to 2T was measured. On the basis of these investigations the saturation magnetization value and the coercive field were determined. Basing on initial magnetization curve analysis in the area of so-called approach to ferromagnetic saturation, the type of structural defects having influence on magnetization in high magnetic fields were determined.

A modified model of magneto-mechanical effect on magnetization in ferromagnetic materials

The prevailing Jiles-Atherton (J-A) model and Zheng Xiao-Jing-Liu Xing-En (Z-L) model are extensively used in modeling the magneto-mechanical effect on magnetization in ferromagnetic materials. In the J-A model, a fitting formula of magnetostrictive strain interms of stress and magnetization is adopted to model the stress effect on magnetostriction. However, the fitting formula is not in good accordance with the experimental results obtained by Kuruzar and Culllity. In order to solve this problem, a transcendental function tanh(<i>x</i>) is appropriately selected to describe the nonlinear magnetostrictive strain in the Z-L model, and it is found that the general formula of magnetostrictive strain is more effective to describe the nonlinear relation of magnetostrictive strain with stress and magnetization. Then, the modified law proposed by Jiles and Li is adopted to modify the Z-L model by Shi Pengpeng to describe the hysteretic behavior; nevertheless, the effect of Weiss molecular field, pinning energy and plastic deformation on magnetization are not taken into account, and the modified Z-L model can only describe the elastic stress effect on magnetization. In order to solve these problems above, a modified magneto-mechanical model is established by combining the magnetostrictive constitutive relationships of Z-L model with the modified energy conservation equation of J-A model, as well as taking the effect of elastic stress and plastic strain on the model parameters into account simultaneously. It is found that the predictions of proposed model here are in better accordance with the initial magnetization curves given by Jiles and Atherton and the hysteresis loops obtained by Makar and Tanner under different stresses and plastic deformation than those calculated by the J-A model and Z-L model. The correlation coefficients between experimental data and theoretical results calculated by the modified model are all over 0.98, which indicates that the modified model here is more effective than the existing model. A detailed study also performed to reveal the effects of the elastic tensile and compressive stress and plastic tensile and compressive strain on hysteresis loops, coercivity and remanence. The proposed model reveals that the area of hysteresis loop and coercivity increase nonlinearly with the stress and plastic deformation increasing, while the remanence decreases significantly; the effects of compressive stress and compressive plastic deformation on magnetization characteristic parameters above are more significant than those of tensile stress and tensile plastic deformation, which is consistent with the experimental trend. The proposed model can be used to quantitatively analyze the magneto-mechanical effect on the magnetization of ferromagnetism.

Detecting Method of Hardened Depth in Surface-Hardened Steel by Magnetic Field on Steel

Detecting Method of Hardened Depth in Surface-Hardened Steel by Magnetic Field on Steel

Effects of Hot-Pressing Temperature on the Magnetic Properties of Hot-Pressed Nanocrystalline Nd–Fe–B Magnets

Bulk nanocrystalline Nd–Fe–B magnets are prepared by the hot-pressing method at different temperatures of 450 °C–650 °C. The initial magnetization curve changes from a single-phase magnetization for the magnets prepared below 600 °C to a two-phase magnetization for the magnets prepared at 650 °C. The Henkel plot is also measured to investigate the exchange coupling interaction, and the results show that two positive peaks occur on the $\delta \text{M}$ curve for the magnet prepared at 650 °C. Scanning electron microscopy results show that the (Pr, Nd)-rich phase is aggregated along the gaps of the ribbons at 650 °C, and the (Pr, Nd)-rich phase behaves magnetically soft property. The inhomogeneous microstructure caused by the aggregation of (Pr, Nd)-rich phase with the temperature increase leads to the change in magnetization behaviors.

Irreversible permeability and DC losses relationship for selected soft magnetic materials

The paper presents the relations for the irreversible permeability at initial magnetization curve, derived and verified for selected soft magnetic materials (FeSi and NiFe steel sheets, compacted and sintered NiFe powder, non-sintered warm compacted Fe powder and Fe-phenolphormaldehyde resin composites). The derivation was based on the Steinmetz law for DC energy losses. Verification of the relations was performed by the comparison of experimental and calculated dependences of the irreversible permeability versus magnetic induction, where the empirical functions in the relations were found. For NiFe steel sheet and all composites the functions were allowed to be taken as constants with a good accuracy. The relations were so proposed for each of the selected soft magnetic materials within the induction ranges covering the ranges of validity of the Steinmetz law.

On the importance of magnetic material characterization for the design of particle accelerator magnets

In this paper, the importance of magnetic material measurements in the framework of the design of magnets for particle accelerator is discussed. In particular, five samples of different ferromagnetic materials are analyzed experimentally and compared with literature results. These materials have been (or will be) used for producing yokes for several normal-conductor magnets at CERN, such as REX-ISOLDE main dipole, ELENA dipole and quadrupole, and SESAME dipole. The comparison with literature shows several disagreements. The main one of them is analyzed in detail in a case study based on finite elements simulation of a quadrupole magnet installed in CERN. This analysis shows that a good knowledge of the yoke initial magnetization curve is important to guarantee a given level of magnet performance, especially concerning its field quality.

Unusual magnetic properties of the polar orthorhombic BiFe0.5Sc0.5O3 perovskite

Magnetic properties of new multiferroic BiFe0.5Sc0.5O3 perovskite which exists in two different orthorhombic polymorphs, the antipolar Pnma and the polar Ima2, were studied using a SQUID-magnetometer technique in magnetic fields up to 50 kOe in the temperature range of 5–300 K. Both polymorphs show a weak ferromagnetic component below the Néel temperature, TN∼220 K. A wide cusp-like anomaly of the temperature dependent magnetic susceptibility was revealed below 200 K. The anomaly is dependent on the magnetic field applied and can be associated with the glassy magnetic behavior of the compound. The best fit of the initial magnetization curves taken at each temperature can be obtained as a sum of two contributions, namely the nonlinear in field and the linear one. The nonlinear contribution appeared to be temperature and magnetic field dependent, which is in a good agreement with the magnetization experimentally obtained as a function of temperature in different magnetic fields applied. Increase of external magnetic field leads to a decrease of the nonlinear contribution to the total magnetic moment.

Magnetic and structural properties of L10 Mn-Ga epitaxially grown islands

Magnetic and structural properties of L10 Mn53Ga47 islands epitaxially grown onto MgO(1 0 0) substrates are discussed. The samples were fabricated by sputter-deposition at a substrate temperature Ts during deposition. The samples deposited at Ts above 500 °C were found to form the island structure of Volmer-Weber type. The average size of the islands fabricated at Ts = 600 °C is around 200 nm in width and 60 nm in height. The XRD and TEM analyses indicate that those islands are of the L10 phase with the 〈0 0 1〉 axis perpendicular to the substrate surface. The lattice constants a and c are 3.91 ± 0.01 Å and 3.65 ± 0.02 Å, respectively, which are larger by 0.8%, and smaller by 1.5% respectively, as compared to the bulk values of the same composition. The order parameter of these islands is found to increase from 0.7 to 0.8 for Ts = 450–500 °C, and then remains nearly constant (≈0.8) for higher Ts. The M-H hysteresis loops exhibit a high squareness for all the samples for Ts = 450–600 °C. The saturation magnetization Ms is about 220 and 350 emu/cm3 for Ts = 450 and 600 °C, respectively. The out-of-plane coercivity Hc is 5 and 13 kOe for Ts = 450 and 600 °C, respectively. The temperature dependence of Ms for the sample made at Ts = 600 °C was measured and fitted to an empirical relation in order to estimate Tc. The estimated Tc around 600 K is in reasonable agreement with the reported value of bulk L10 Mn53Ga47. The uniaxial perpendicular magnetic anisotropy constant Ku estimated by the out-of-plane torque curves is around 1.1 × 107 and 8.3 × 106 erg/cm3 at 5 and 300 K, respectively. The initial magnetization curves of these islands exhibit a typical pinning mode for the coercivity mechanism. A phenomenological discussion of the coercivity is presented on the basis of Kronmuller’s formula. It is found that the coefficient α and effective demagnetizing factor Neff in the formula by Kronmuller are approximately 0.38 and 12. For the magnetic anisotropy mechanism, the power law relation between Ku(T) and Ms(T) is examined. It is found that the exponent n for Ku(T)∝Ms(T)n varies from 2.3 to 3.5 for T from 350 to 5 K. However, the n in a whole temperature range from 5 to 350 K is 2.6. The n = 2.6 suggests a deviation from the single-ion mechanism, and is consistent with the theoretical predictions of Ga contribution.

Phase formation and magnetic hardening mechanism of TbCu7 type Sm-Fe-N powders

(Sm0.7Zr0.3)x(Fe0.9Co0.1)100−x (x = 9.1,10.7,10.9,12.6,13.4) alloys almost consistof TbCu7 type phase were prepared by rapid quenching technique and annealing. A series of TbCu7 type Sm-Zr-Fe-Co-N magnetically hard powders were prepared through nitrogenization of the alloys. With (Sm0.7Zr0.3) content increases, the coercivity increased but magnetization decreases. TbCu7-type nitride powder with coercivity of 10.8 kOe can be obtained when x = 13.6. The initial magnetization curves of the powders indicate that the coercivity should be controlled by pinning mechanism.

Magnetic and Dielectric Properties of Y3−x Sm x Fe5O12 (x = 0.0 to 3.0)

Single-phase polycrystalline samples of Y3−x Sm x Fe5O12 (x = 0.0–3.0) were prepared by using a solid-state reaction method. The lattice constant is found to increase from 12.372 A for x = 0.0 to 12.524 A for $x = 3.0$ . The substitution of Sm3+ at Y3+ site is confirmed from the red shift of Raman F2g mode. Magnetization loops measured at room temperature and the analysis of initial magnetization curves show that saturation magnetization value decreases with an increase in Sm concentration due to the possible antiferromagnetic interaction. On the other hand, temperature variation of magnetization plots shows that all the samples exhibit ferrimagnetic transition with transition temperature in the range of 550 K for x = 0.0 to 573 K for $x = 3.0$ . The dielectric constant increases upon Sm substitution, and the analysis of impedance and dielectric spectra shows the contribution of both grains and grain boundaries.

Ferromagnetism in Fe-doped BaTiO3 Ceramics

Polycrystalline samples of BaTi1−xFexO3 (x = 0.00–0.30) are prepared by solid-state reaction method and their structural and magnetic properties are studied. Detailed investigation of XRD patterns reveal the coexistence of tetragonal (space group P4mm) and hexagonal phases (space group P6 3/mmc) for x ≥ 0.1. Magnetic measurements reveal room-temperature ferromagnetism in x = 0.15–0.3 samples, and their ferromagnetic transition temperature increases from 397 K for x = 0.15 to 464 K for x = 0.3. The initial magnetization curves for x = 0.15–0.3 are analyzed in terms of bound magnetic polaron (BMP) model. The analysis of susceptibility data in the paramagnetic region by Curie-Weiss law confirms the ferromagnetic transition for x ≥ 0.15 and the effective magnetic moment systematically increases with increase in Fe concentration.

Comparison of angular dependence of magnetic Barkhausen noise of hysteresis and initial magnetization curve in API5L steel

This work analyzes the differences between the magnetic Barkhausen noise corresponding to the initial magnetization curve and Barkhausen noise corresponding to one branch of the hysteresis loop in API-5L steel. The outcomes show that the Barkhausen noise signal corresponding to the initial magnetization curve and that corresponding to the hysteresis are significantly different. This difference is due to the presence of different processes of the domain wall dynamics in both phenomena. To study the processes present in magnetization dynamics for an applied field of H>0, research into the angular dependence of a Barkhausen signal using applied field bands has revealed that a Barkhausen signal corresponding to the initial magnetization curve is more suitable than a Barkhausen signal corresponding to the hysteresis loop.

Enhanced magneto-caloric effect upon Co substitution in Ni-Mn-Sn thin films

Mn rich Ni-Mn-Sn and Ni-Mn-Co-Sn alloy films were deposited on Si (100) substrate by dc magnetron sputtering from Ni50Mn37Sn13 alloy target at 1.8Pa Ar pressure with 70W dc power. Co was introduced by placing Co chips on the Ni-Mn-Sn target. As-deposited films were vacuum annealed at 823K for 1h. X-ray diffraction patterns of the films revealed modulated 14M structure of the martensite phase at room temperature. Magnetic entropy change (ΔSm) across the Curie temperature of the ferromagnetic films was estimated from initial isothermal magnetization curves using Maxwell’s equation. ΔSm and refrigeration capacity (RC) of Ni-Mn-Sn and Ni-Mn-Co-Sn films increased with increasing film thickness. Upon Co substitution in Mn/Sn site(s), ΔSm and RC increased more remarkably. The change is more prominent in the case of 360nm films, wherein a 3.8-fold increase in ΔSM and 8.9-fold increase in RC was observed. Introduction of Co increased the magnetic moment and broadened the magnetic transition. These factors increased ΔSm and RC in Co substituted Ni-Mn-Sn alloy. Since TC shifted to higher temperatures with Co substitution, operating temperature of these magnetic refrigerants also shifted to higher temperature. This study indicates the possibility of developing high temperature cooling devices and waste energy harvesters using these films.

Comparative Magnetic and Structural Properties Study of Micro- and Nanopowders of Nd2Fe14B Doped with Ni

Micropowders of melted and heat-treated Nd16(Fe76−xNix)B8 alloys system, with x = 0, 10, 20, and 25 (size distribution under 20 μm), were studied and compared with the study of nanopowders obtained, from the previous ones, by surfactant-assisted ball-milling process during 2 h. By XRD, a majority of Nd2Fe14B hard phase and a minority of α-Fe, Nd1.1Fe4B4 and NdNi2 phases were detected. The last one increases with Ni content. The crystallite size of the hard phase, in both types of samples, is not affected by the Ni content; however, the grains in micropowders are oblate, with a mean size of 37 nm, while those of the nanopowders are symmetric, with a mean size of 35 nm. Mossbauer spectra were fitted with seven sextets, which correspond to the six ferromagnetic sites of the hard phase and that of the α-Fe, and a doublet corresponding to the paramagnetic Nd1.1Fe4B4 phase. The mean hyperfine magnetic field, for both types of samples, decreases with Ni content. The hysteresis loops of both types of samples show a hard magnetic character, however, the coercive field and the Mr/Ms values for nanopowders are greater than those obtained for micropowders for all the Ni contents. Values of Hc = 2 kOe and Mr/ Ms = 0.54 were obtained for nanopowders with 10 at.% Ni. From the hysteresis loops, which include the initial magnetization curve, Henkel plots for all the samples were obtained. These plots show that for micropowders, the predominant magnetic interaction is of dipolar type, while for nanopowders, the ferromagnetic exchange is the predominant one, which favored the magnetization.