Materials

Editorial

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4 pages, 157 KiB

Open AccessEditorial

Special Issue: “Soft Magnetic Materials and Their Applications”

by Shenglei Che

Materials 2024, 17(1), 89; https://doi.org/10.3390/ma17010089 - 23 Dec 2023

Cited by 2 | Viewed by 2172

Abstract

Soft magnetic materials normally show no magnetic properties outside of a magnetic field but can be easily magnetized and demagnetized within magnetic fields [...] Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

Research

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11 pages, 6953 KiB

Open AccessArticle

A Study on an Easy-Plane FeSi_3.5 Composite with High Permeability and Ultra-Low Loss at the MHz Frequency Band

by Peng Wu, Shengyu Yang, Yuandong Huang, Guowu Wang, Jinghao Cui, Liang Qiao, Tao Wang and Fashen Li

Materials 2023, 16(14), 5133; https://doi.org/10.3390/ma16145133 - 21 Jul 2023

Cited by 5 | Viewed by 1625

Abstract

An easy-plane FeSi_3.5 composite with excellent magnetic properties and loss properties at MHz were proposed. The easy-plane FeSi_3.5 composite has ultra-low loss at 10 MHz and 4 mT, about 372.88 kW/m³. In order to explore the reason that the [...] Read more.

An easy-plane FeSi_3.5 composite with excellent magnetic properties and loss properties at MHz were proposed. The easy-plane FeSi_3.5 composite has ultra-low loss at 10 MHz and 4 mT, about 372.88 kW/m³. In order to explore the reason that the

P_{c v}

of easy-plane FeSi_3.5 composite is ultra-low, a none easy-plane FeSi_3.5 composite, without easy-plane processing as a control group, measured the microstructure, and the magnetic and loss properties. We first found that the real reason why magnetic materials do not work properly at MHz due to overheat is dramatical increase of the excess loss and the easy-plane composite can greatly re-duce the excess loss by loss measurement and separation. The total loss of none easy-plane FeSi_3.5 composite is much higher than that of easy-plane FeSi_3.5 composite, where the excess loss is a major part in the total loss and even over 80% in the none easy-plane FeSi_3.5 composite. The easy-plane FeSi_3.5 composite can greatly reduce the total loss compared to the none easy-plane FeSi_3.5 composite, from 2785.8 kW/m³ to 500.42 kW/m³ (3 MHz, 8 mT), with the main reduction being the excess loss, from 2435.2 kW/m³ to 204.93 kW/m³ (3 MHz, 8 mT), reduced by 91.58%. Furthermore, the easy-plane FeSi_3.5 composite also has excellent magnetic properties, high permeability and ferromagnetic resonance frequencies. This makes the easy-plane FeSi_3.5 composite become an excellent soft magnetic composite and it is possible for magnetic devices to operate properly at higher frequencies, especially at the MHz band and above. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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12 pages, 2752 KiB

Open AccessArticle

Correlation of Magnetomechanical Coupling and Damping in Fe₈₀Si₉B₁₁ Metallic Glass Ribbons

by Xu Zhang, Yu Sun, Bin Yan and Xin Zhuang

Materials 2023, 16(14), 4990; https://doi.org/10.3390/ma16144990 - 14 Jul 2023

Cited by 3 | Viewed by 1190

Abstract

Understanding the correlation between magnetomechanical coupling factors (k) and damping factors (Q⁻¹) is a key pathway toward enhancing the magnetomechanical power conversion efficiency in laminated magnetoelectric (ME) composites by manipulating the magnetic and mechanical properties of Fe-based [...] Read more.

Understanding the correlation between magnetomechanical coupling factors (k) and damping factors (Q⁻¹) is a key pathway toward enhancing the magnetomechanical power conversion efficiency in laminated magnetoelectric (ME) composites by manipulating the magnetic and mechanical properties of Fe-based amorphous metals through engineering. The k and Q⁻¹ factors of FeSiB amorphous ribbons annealed in air at different temperatures are investigated. It is found that k and Q⁻¹ factors are affected by both magnetic and elastic properties. The magnetic and elastic properties are characterized in terms of the magnetomechanical power efficiency for low-temperature annealing. The k and Q⁻¹ of FeSiB-based epoxied laminates with different stacking numbers show that a −3 dB bandwidth and Young’s modulus are expressed in terms of the magnetomechanical power efficiency for high lamination stacking. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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12 pages, 11154 KiB

Open AccessArticle

Preparation of Densified Fine-Grain High-Frequency MnZn Ferrite Using the Cold Sintering Process

by Yao Ying, Linghuo Hu, Zhaocheng Li, Jingwu Zheng, Jing Yu, Wangchang Li, Liang Qiao, Wei Cai, Juan Li, Daxin Bao and Shenglei Che

Materials 2023, 16(9), 3454; https://doi.org/10.3390/ma16093454 - 28 Apr 2023

Cited by 9 | Viewed by 2809

Abstract

The densified MnZn ferrite ceramics were prepared using the cold sintering process under pressure, with an acetate ethanol solution used as the transient solvent. The effects of the transient solvent, the pressure and annealing temperature on the density, and the micromorphology and magnetic [...] Read more.

The densified MnZn ferrite ceramics were prepared using the cold sintering process under pressure, with an acetate ethanol solution used as the transient solvent. The effects of the transient solvent, the pressure and annealing temperature on the density, and the micromorphology and magnetic properties of the sintered MnZn ferrites were studied. The densified MnZn ferrite was obtained using the cold sintering process and its relative density reached up to 85.4%. The transient solvent and high pressure are essential to the cold sintering process for MnZn ferrite. The annealing treatment is indispensable in obtaining the sample with the higher density. The relative density was further increased to 97.2% for the sample annealed at 950 °C for 6 h. The increase in the annealing temperature reduces the power loss at high frequencies. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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11 pages, 3677 KiB

Open AccessArticle

Study of the Soft Magnetic Properties of FeSiAl Magnetic Powder Cores by Compounding with Different Content of Epoxy Resin

by Zhengqu Zhu, Jiaqi Liu, Huan Zhao, Jing Pang, Pu Wang and Jiaquan Zhang

Materials 2023, 16(3), 1270; https://doi.org/10.3390/ma16031270 - 2 Feb 2023

Cited by 13 | Viewed by 2660

Abstract

FeSiAl is a commonly used soft magnetic material because of its high resistivity, low core loss, and low cost. In order to systematically study the effect of epoxy resin (EP) on the insulated coating and pressing effect of FeSiAl magnetic powders, six groups [...] Read more.

FeSiAl is a commonly used soft magnetic material because of its high resistivity, low core loss, and low cost. In order to systematically study the effect of epoxy resin (EP) on the insulated coating and pressing effect of FeSiAl magnetic powders, six groups of composite powders and their corresponding soft magnetic powder cores (SMPCs) were prepared by changing the content of EP, and the soft magnetic properties of the powders and SMPCs were characterized. The results showed that FeSiAl powders exhibited good sphericity and morphology. The M_s of FeSiAl/EP composite powders was between 117.4–124.8 emu·g⁻¹ after adding (0.3, 0.5, 0.7, 1, 1.5, and 2 wt. %) EP. The permeability μ_e of SMPCs increased first and then decreased with the increase in EP content. Among them, when the EP content was 1 wt. %, the corresponding SMPCs had the highest μ_e and excellent DC bias performance (63%, 100 Oe). In the whole test frequency range (50~1000 kHz), SMPCs with 1 wt. % EP content had the lowest core loss (1733.9 mW·cm⁻³ at 20 mT and 1000 kHz). After that, the loss separation study in the low-frequency range (50~250 kHz) was conducted, and the hysteresis loss and eddy current loss of SMPCs with 1 wt. % EP content were also the lowest. In addition, SMPCs also exhibited the best overall performance when the EP content was 1 wt. %. The results of this study can guide the design of composite insulation coating schemes and promote the development of soft magnetic materials for medium and high frequency applications. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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9 pages, 3075 KiB

Open AccessArticle

Testing and Analysis Method of Low Remanence Materials for Magnetic Shielding Device

by Yuan Cheng, Yaozhi Luo, Ruihong Shen, Deyu Kong and Weiyong Zhou

Materials 2023, 16(2), 681; https://doi.org/10.3390/ma16020681 - 10 Jan 2023

Cited by 5 | Viewed by 2497

Abstract

Magnetic shielding devices with a grid structure of multiple layers of highly magnetically permeable materials (such as permalloy) can achieve remanent magnetic fields at the nanotesla (nT) level or even lower. The remanence of the material inside the magnetic shield, such as the [...] Read more.

Magnetic shielding devices with a grid structure of multiple layers of highly magnetically permeable materials (such as permalloy) can achieve remanent magnetic fields at the nanotesla (nT) level or even lower. The remanence of the material inside the magnetic shield, such as the building materials used in the support structure, can cause serious damage to the internal remanence of the magnetic shield. Therefore, it is of great significance to detect the remanence of the materials used inside the magnetic shielding device. The existing test methods do not limit the test environment, the test process is vulnerable to additional magnetic field interference and did not consider the real results of the material in the weak magnetic environment. In this paper, a novel method of measuring the remanence of materials in a magnetic shielding cylinder is proposed, which prevents the interference of the earth’s magnetic field and reduces the measurement error. This method is used to test concrete components, composite materials and metal materials commonly applicated in magnetic shielding devices and determine the materials that can be used for magnetic shielding devices with 1 nT, 10 nT and 100 nT as residual magnetic field targets. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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9 pages, 1966 KiB

Open AccessArticle

Influence of MnZn Ferrite Homogeneous Fibers on the Microstructure, Magnetic, and Mechanical Properties of MnZn Ferrite Materials

by Yajing Shang, Fan Luo and Zhongxia Duan

Materials 2023, 16(1), 209; https://doi.org/10.3390/ma16010209 - 26 Dec 2022

Cited by 6 | Viewed by 1912

Abstract

MnZn ferrite homogeneous fibers were synthesized via a simple solvothermal method and they were used as a reinforcing phase to prepare homogeneous-fiber-reinforced MnZn ferrite materials. The effects of MnZn ferrite homogeneous fibers (0 wt% to 4 wt%) doping on the microstructure, magnetic, and [...] Read more.

MnZn ferrite homogeneous fibers were synthesized via a simple solvothermal method and they were used as a reinforcing phase to prepare homogeneous-fiber-reinforced MnZn ferrite materials. The effects of MnZn ferrite homogeneous fibers (0 wt% to 4 wt%) doping on the microstructure, magnetic, and mechanical properties of MnZn ferrite materials were studied systematically. The results showed that MnZn ferrite homogeneous fibers exhibited high purity, good crystallinity, and smooth 1D fibrous structures, which were homogeneous with MnZn ferrite materials. Simultaneously, a certain content of MnZn ferrite homogeneous fibers helped MnZn ferrite materials exhibit more uniform and compact crystal structures, less porosity, and fewer grain boundaries. In addition, the homogeneous-fiber-reinforced MnZn ferrite materials possessed superior magnetic and mechanical properties such as higher effective permeability, lower magnetic loss, and higher Vickers hardness compared to ordinary MnZn ferrite materials. In addition, the magnetic and mechanical properties of homogeneous-fiber-reinforced MnZn ferrite materials first increased and then gradually decreased as the homogeneous fiber content increased from 0 wt% to 4 wt%. The best magnetic and mechanical properties of materials were obtained as the fiber content was about 2 wt%. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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13 pages, 2478 KiB

Open AccessArticle

Analysis and Measurement of Differential-Mode Magnetic Noise in Mn-Zn Soft Ferrite Shield for Ultra-Sensitive Sensors

by Danyue Ma, Xiujie Fang, Jixi Lu, Kun Wang, Bowen Sun, Yanan Gao, Xueping Xu and Bangcheng Han

Materials 2022, 15(23), 8704; https://doi.org/10.3390/ma15238704 - 6 Dec 2022

Cited by 4 | Viewed by 1879

Abstract

The magnetic noise generated by the ferrite magnetic shield affects the performance of ultra-sensitive atomic sensors. Differential measurement can effectively suppress the influence of common-mode (CM) magnetic noise, but the limit of suppression capability is not clear at present. In this paper, a [...] Read more.

The magnetic noise generated by the ferrite magnetic shield affects the performance of ultra-sensitive atomic sensors. Differential measurement can effectively suppress the influence of common-mode (CM) magnetic noise, but the limit of suppression capability is not clear at present. In this paper, a finite element analysis model using power loss to calculate differential-mode (DM) magnetic noise under a ferrite magnetic shield is proposed. The experimental results confirm the feasibility of the model. An ultrahigh-sensitive magnetometer was built, the single channel magnetic noise measured and the differential-mode (DM) magnetic noise are 0.70 fT/Hz^1/2 and 0.10 fT/Hz^1/2 @30 Hz. The DM magnetic noise calculated by the proposed model is less than 5% different from the actual measured value. To effectively reduce DM magnetic noise, we analyze and optimize the structure parameters of the shield on the DM magnetic noise. When the outer diameter is fixed, the model is used to analyze the influence of the ratio of ferrite magnetic shielding thickness to outer diameter, the ratio of length to outer diameter, and the air gap between magnetic annuli on DM magnetic noise. The results show that the axial DM magnetic noise and radial DM magnetic noise reach the optimal values when the thickness to outer diameter ratio is 0.08 and 0.1. The ratio of length to outer diameter is negatively correlated with DM magnetic noise, and the air gap (0.1–1 mm) is independent of DM magnetic noise. The axial DM magnetic noise is less than that of radial DM magnetic noise. These results are useful for suppressing magnetic noise and breaking through the sensitivity of the magnetometer. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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11 pages, 3005 KiB

Open AccessArticle

Low Core Losses of Fe-Based Soft Magnetic Composites with an Zn-O-Si Insulating Layer Obtained by Coupling Synergistic Photodecomposition

by Siyuan Wang, Jingwu Zheng, Danni Zheng, Liang Qiao, Yao Ying, Yiping Tang, Wei Cai, Wangchang Li, Jing Yu, Juan Li and Shenglei Che

Materials 2022, 15(23), 8660; https://doi.org/10.3390/ma15238660 - 5 Dec 2022

Cited by 3 | Viewed by 1838

Abstract

The major method used to reduce the magnetic loss of soft magnetic composites (SMCs) is to coat the magnetic powder with an insulating layer, but the permeability is usually sacrificed in the process. In order to achieve a better balance between low losses [...] Read more.

The major method used to reduce the magnetic loss of soft magnetic composites (SMCs) is to coat the magnetic powder with an insulating layer, but the permeability is usually sacrificed in the process. In order to achieve a better balance between low losses and high permeability, a novel photodecomposition method was used in this study to create a ZnO insulating layer. The effect of the concentration of diethyl zinc on the formation of a ZnO insulating film by photodecomposition was studied. The ZnO film was best formed with a diethyl zinc n-hexane solution at a concentration of around 0.40 mol/L. Combined with conventional coupling treatment processes, a thin and dense insulating layer was coated on the surface of iron powder in situ. Treating the iron powder before coating by photodecomposition led to a synergistic effect, significantly reduced core loss, and the effective permeability only decreased slightly. An iron-based soft magnetic composite with a loss value of 124 kW/m³ and an effective permeability of 107 was obtained at the frequency of 100 kHz and a magnetic field intensity of 20 mT. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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17 pages, 5780 KiB

Open AccessArticle

Investigation and Application of Magnetic Properties of Ultra-Thin Grain-Oriented Silicon Steel Sheets under Multi-Physical Field Coupling

by Zhiye Li, Yuechao Ma, Anrui Hu, Lubin Zeng, Shibo Xu and Ruilin Pei

Materials 2022, 15(23), 8522; https://doi.org/10.3390/ma15238522 - 29 Nov 2022

Cited by 7 | Viewed by 2651

Abstract

Nowadays, energy shortages and environmental pollution have received a lot of attention, which makes the electrification of transportation systems an inevitable trend. As the core part of an electrical driving system, the electrical machine faces the extreme challenge of keeping high power density [...] Read more.

Nowadays, energy shortages and environmental pollution have received a lot of attention, which makes the electrification of transportation systems an inevitable trend. As the core part of an electrical driving system, the electrical machine faces the extreme challenge of keeping high power density and high efficiency output under complex workin g conditions. The development and research of new soft magnetic materials has an important impact to solve the current bottleneck problems of electrical machines. In this paper, the variation trend of magnetic properties of ultra-thin grain-oriented silicon steel electrical steel (GOES) under thermal-mechanical-electric-magnetic fields is studied, and the possibility of its application in motors is explored. The magnetic properties of grain-oriented silicon steel samples under different conditions were measured by the Epstein frame method and self-built multi-physical field device. It is verified that the magnetic properties of grain-oriented silicon steel selected within 30° magnetization deviation angle are better than non-grain-oriented silicon steel. The magnetic properties of the same ultra-thin grain-oriented silicon steel as ordinary non-oriented silicon steel deteriorate with the increase in frequency. Different from conventional non-grain-oriented silicon steel, its magnetic properties will deteriorate with the increase in temperature. Under the stress of 30 Mpa, the magnetic properties of the grain-oriented silicon steel are the best; under the coupling of multiple physical fields, the change trend of magnetic properties of grain-oriented silicon steel is similar to that of single physical field, but the specific quantitative values are different. Furthermore, the application of grain-oriented silicon steel in interior permanent magnet synchronous motor (IPM) for electric vehicles is explored. Through a precise oriented silicon steel motor model, it is proved that the magnetic flux density of stator teeth increases by 2.2%, the electromagnetic torque of motor increases by 2.18%, and the peak efficiency increases by 1% after using grain-oriented silicon steel. In this paper, through the investigation of the characteristics of grain-oriented silicon steel, it is preliminarily verified that grain-oriented silicon steel has a great application prospect in the drive motor (IPM) of electric vehicles, and it is an effective means to break the bottleneck of current motor design. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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16 pages, 12882 KiB

Open AccessArticle

Study of High-Silicon Steel as Interior Rotor for High-Speed Motor Considering the Influence of Multi-Physical Field Coupling and Slotting Process

by Deji Ma, Baozhi Tian, Xuejie Zheng, Yulin Li, Shibo Xu and Ruilin Pei

Materials 2022, 15(23), 8502; https://doi.org/10.3390/ma15238502 - 29 Nov 2022

Cited by 3 | Viewed by 2612

Abstract

Currently, high-speed motors usually adopt rotor structures with surface-mounted permanent magnets, but their sheaths will deteriorate performance significantly. The motor with interior rotor structure has the advantages of high power density and efficiency. At the same time, high silicon steel has low loss [...] Read more.

Currently, high-speed motors usually adopt rotor structures with surface-mounted permanent magnets, but their sheaths will deteriorate performance significantly. The motor with interior rotor structure has the advantages of high power density and efficiency. At the same time, high silicon steel has low loss and high mechanical strength, which is extremely suitable for high-speed motor rotor core material. Therefore, in this paper, the feasibility of using high silicon steel as the material of an interior rotor high-speed motor is investigated. Firstly, the magnetic properties of high silicon steel under multi-physical fields were tested and analyzed in comparison with conventional silicon steel. Meanwhile, an interior rotor structure of high-speed motor using high silicon steel as the rotor core is proposed, and its electromagnetic, mechanical, and thermal properties are simulated and evaluated. Then, the experimental comparative analysis was carried out in terms of the slotting process of the core, and the machining of the high silicon steel rotor core was successfully completed. Finally, the feasibility of the research idea was verified by the above theoretical analysis and experimental characterization. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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12 pages, 6329 KiB

Open AccessArticle

Transient Magnetic Properties of Non-Grain Oriented Silicon Steel under Multi-Physics Field

by Anqi Wang, Baozhi Tian, Yulin Li, Shibo Xu, Lubin Zeng and Ruilin Pei

Materials 2022, 15(23), 8305; https://doi.org/10.3390/ma15238305 - 23 Nov 2022

Cited by 5 | Viewed by 1783

Abstract

High-speed, high-efficiency and high-power density are the main development trends of high-performance motors in the future. At present, the design accuracy of traditional electric machines is already high enough; however, for the future demand of high performance and utilization in special environments (such [...] Read more.

High-speed, high-efficiency and high-power density are the main development trends of high-performance motors in the future. At present, the design accuracy of traditional electric machines is already high enough; however, for the future demand of high performance and utilization in special environments (such as aviation and aerospace fields), more thorough research of materials’ performance under multi-physics field (MPF) conditions is still needed. In this paper, a test system that combined temperature, stress and electromagnetic fields along with other fields, at the same time, is built. It can accurately simulate the actual complex working conditions of the motor and explore the dynamic characteristics of non-grain oriented (NGO) silicon steel. The rationality of this method is verified by checking the test result of the prototype, and the calculation accuracy of the motor model is improved. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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11 pages, 4907 KiB

Open AccessArticle

Study on the Magnetic Noise Characteristics of Amorphous and Nanocrystalline Inner Magnetic Shield Layers of SERF Co-Magnetometer

by Ye Liu, Hang Gao, Longyan Ma, Jiale Quan, Wenfeng Fan, Xueping Xu, Yang Fu, Lihong Duan and Wei Quan

Materials 2022, 15(22), 8267; https://doi.org/10.3390/ma15228267 - 21 Nov 2022

Cited by 13 | Viewed by 2283

Abstract

With the widespread use of magneto-sensitive elements, magnetic shields are an important part of electronic equipment, ultra-sensitive atomic sensors, and in basic physics experiments. Particularly in Spin-exchange relaxation-free (SERF) co-magnetometers, the magnetic shield is an important component for maintaining the SERF state. However, [...] Read more.

With the widespread use of magneto-sensitive elements, magnetic shields are an important part of electronic equipment, ultra-sensitive atomic sensors, and in basic physics experiments. Particularly in Spin-exchange relaxation-free (SERF) co-magnetometers, the magnetic shield is an important component for maintaining the SERF state. However, the inherent noise of magnetic shield materials is an important factor limiting the measurement sensitivity and accuracy of SERF co-magnetometers. In this paper, both amorphous and nanocrystalline materials were designed and applied as the innermost magnetic shield of an SERF co-magnetometer. Magnetic noise characteristics of different amorphous and nanocrystalline materials used as the internal magnetic shielding layer of the magnetic shielding system were analyzed. In addition, the effects on magnetic noise due to adding aluminum to amorphous and nanocrystalline materials were studied. The experimental results show that compared with an amorphous material, a nanocrystalline material as the inner magnetic shield layer can effectively reduce the magnetic noise and improve the sensitivity and precision of the rotation measurement. Nanocrystalline material is very promising for inner shield composition in SERF co-magnetometers. Furthermore, its ultra-thin structure and low cost have significant application value in the miniaturization of SERF co-magnetometers. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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10 pages, 1750 KiB

Open AccessFeature PaperArticle

A Method to Measure Permeability of Permalloy in Extremely Weak Magnetic Field Based on Rayleigh Model

by Jinji Sun, Yan Lu, Lu Zhang, Yun Le and Xiuqi Zhao

Materials 2022, 15(20), 7353; https://doi.org/10.3390/ma15207353 - 20 Oct 2022

Cited by 6 | Viewed by 2295

Abstract

In order to solve the problem that the relative permeability of the permalloy is missing and difficult to measure accurately in an extremely weak magnetic field (EWMF, <1 nT), a method to measure the permeability in EWMF based on the Rayleigh model is [...] Read more.

In order to solve the problem that the relative permeability of the permalloy is missing and difficult to measure accurately in an extremely weak magnetic field (EWMF, <1 nT), a method to measure the permeability in EWMF based on the Rayleigh model is proposed in this paper. In this method, the Rayleigh model for the magnetic material was first introduced. Then, the test system for measuring the permeability of permalloy for the standard ring specimen was set up. Based on the test data and the Rayleigh model, the functional expression applied to obtain the permeability in EWMF is achieved. Finally, the feasibility and accuracy of the method are verified by the permeability measurement of the custom large-size ring specimen in EWMF (<1 nT) and residual field measurement based on the four-layer shielding cylinder. This method can obtain the relative permeability in any EWMF and avoid test errors caused by extremely weak magnetization signals. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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9 pages, 7103 KiB

Open AccessArticle

The Preparation of High Saturation Magnetization and Low Coercivity Feco Soft Magnetic Thin Films via Controlling the Thickness and Deposition Temperature

by Wenjie Yang, Junjie Liu, Xiangfeng Yu, Gang Wang, Zhigang Zheng, Jianping Guo, Deyang Chen, Zhaoguo Qiu and Dechang Zeng

Materials 2022, 15(20), 7191; https://doi.org/10.3390/ma15207191 - 15 Oct 2022

Cited by 9 | Viewed by 2568

Abstract

FeCo thin films with high saturation magnetization (4 πM_s) can be applied in high-frequency electronic devices such as thin film inductors and microwave noise suppressors. However, due to its large magnetocrystalline anisotropy constant and magnetostrictive coefficient of FeCo, the coercivity [...] Read more.

FeCo thin films with high saturation magnetization (4 πM_s) can be applied in high-frequency electronic devices such as thin film inductors and microwave noise suppressors. However, due to its large magnetocrystalline anisotropy constant and magnetostrictive coefficient of FeCo, the coercivity (H_c) of FeCo films is generally high, which is detrimental to the soft magnetic properties. Meanwhile, the thickness and deposition temperature have significant effects on the coercivity and saturation magnetization of FeCo films. In this paper, FeCo thin films with different thicknesses were prepared by magnetron sputtering at different temperatures. The effects of thickness and deposition temperature on the microstructure and magnetic properties of FeCo thin films were systematically studied. When the film thickness increases from 50 nm to 800 nm, the coercivity would decrease from 309 Oe to 160 Oe. However, the saturation magnetization decreases from 22.1 kG to 15.3 kG. After that, we try to further increase the deposition temperature from room temperature (RT) to 475 °C. It is intriguing to find that the coercivity greatly decreased from 160 Oe to 3 Oe (decreased by 98%), and the saturation magnetization increased from 15.3 kG to 23.5 kG (increased by 53%) for the film with thickness of 800 nm. For the film with thickness of 50 nm, the coercivity also greatly decreased from 309 Oe to 10 Oe (decreased by 96%), but the saturation magnetization did not change significantly. It is contributed to the increase of deposition temperature, which will lead to the increase of grain size and the decrease of the number of grain boundaries. And the coercivity decreases as the number of grain boundaries decreases. Meanwhile, for the thicker films, when increasing the deposition temperature the thermal stress increases, which changes the appearance of (200) texture, and the saturation magnetization increases. Whereas, it has a negligible effect on the orientation of thin films with small thickness (50 nm). This indicates that high-temperature deposition is beneficial to the soft magnetic properties of FeCo thin films, particularly for the films with larger thickness. This FeCo thin film with high saturation magnetization and low coercivity could be an ideal candidate for high-frequency electronic devices. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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10 pages, 1948 KiB

Open AccessArticle

Analysis and Suppression of Thermal Magnetic Noise of Ferrite in the SERF Co-Magnetometer

by Haoying Pang, Feng Liu, Wengfeng Fan, Jiaqi Wu, Qi Yuan, Zhihong Wu and Wei Quan

Materials 2022, 15(19), 6971; https://doi.org/10.3390/ma15196971 - 7 Oct 2022

Cited by 8 | Viewed by 1964

Abstract

The ferrite magnetic shield is widely used in ultra-high-sensitivity atomic sensors because of its low noise characteristics. However, its noise level varies with temperature and affects the performance of the spin-exchange relaxation-free (SERF) co-magnetometer. Therefore, it is necessary to analyze and suppress the [...] Read more.

The ferrite magnetic shield is widely used in ultra-high-sensitivity atomic sensors because of its low noise characteristics. However, its noise level varies with temperature and affects the performance of the spin-exchange relaxation-free (SERF) co-magnetometer. Therefore, it is necessary to analyze and suppress the thermal magnetic noise. In this paper, the thermal magnetic noise model of a ferrite magnetic shield is established, and the thermal magnetic noise of ferrite is calculated more accurately by testing the low-frequency complex permeability at different temperatures. A temperature suppression method based on the improved heat dissipation efficiency of the ferrite magnetic shield is also proposed. The magnetic noise of the ferrite is reduced by 46.7%. The experiment is basically consistent with the theory. The sensitivity of the co-magnetometer is decreased significantly, from 1.21 ×

10^{- 5}

°

/s/Hz

^{1 / 2}

to 7.02 ×

10^{- 6}

°

/s/Hz

^{1 / 2}

at 1 Hz. The experimental results demonstrate the effectiveness of the proposed method. In addition, the study is also helpful for evaluating the thermal magnetic noise of other materials. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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11 pages, 3346 KiB

Open AccessArticle

A High-Performance Magnetic Shield with MnZn Ferrite and Mu-Metal Film Combination for Atomic Sensors

by Xiujie Fang, Danyue Ma, Bowen Sun, Xueping Xu, Wei Quan, Zhisong Xiao and Yueyang Zhai

Materials 2022, 15(19), 6680; https://doi.org/10.3390/ma15196680 - 26 Sep 2022

Cited by 13 | Viewed by 3018

Abstract

This study proposes a high-performance magnetic shielding structure composed of MnZn ferrite and mu-metal film. The use of the mu-metal film with a high magnetic permeability restrains the decrease in the magnetic shielding coefficient caused by the magnetic leakage between the gap of [...] Read more.

This study proposes a high-performance magnetic shielding structure composed of MnZn ferrite and mu-metal film. The use of the mu-metal film with a high magnetic permeability restrains the decrease in the magnetic shielding coefficient caused by the magnetic leakage between the gap of magnetic annuli. The 0.1–0.5 mm thickness of mu-metal film prevents the increase of magnetic noise of composite structure. The finite element simulation results show that the magnetic shielding coefficient and magnetic noise are almost unchanged with the increase in the gap width. Compared with conventional ferrite magnetic shields with multiple annuli structures under the gap width of 0.5 mm, the radial shielding coefficient increases by 13.2%, and the magnetic noise decreases by 21%. The axial shielding coefficient increases by 22.3 times. Experiments verify the simulation results of the shielding coefficient of the combined magnetic shield. The shielding coefficient of the combined magnetic shield is 16.5%. It is 91.3% higher than the conventional ferrite magnetic shield. The main difference is observed between the actual and simulated relative permeability of mu-metal films. The combined magnetic shielding proposed in this study is of great significance to further promote the performance of atomic sensors sensitive to magnetic field. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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Review

Jump to: Editorial, Research

10 pages, 2798 KiB

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Effect of Al and La Doping on the Structure and Magnetostrictive Properties of Fe₇₃Ga₂₇ Alloy

by Jinchao Du, Pei Gong, Xiao Li, Shaoqi Ning, Wei Song, Yuan Wang and Hongbo Hao

Materials 2023, 16(1), 12; https://doi.org/10.3390/ma16010012 - 20 Dec 2022

Cited by 14 | Viewed by 1549

Abstract

The changes of microstructure, magnetostriction properties and hardness of the Fe₇₃Ga_27−xAl_x alloy and (Fe₇₃Ga_27−xAl_x)_99.9La_0.1 alloy (x = 0, 0.5, 1.5, 2.5, 3.5, 4.5) were studied by doping Al into [...] Read more.

The changes of microstructure, magnetostriction properties and hardness of the Fe₇₃Ga_27−xAl_x alloy and (Fe₇₃Ga_27−xAl_x)_99.9La_0.1 alloy (x = 0, 0.5, 1.5, 2.5, 3.5, 4.5) were studied by doping Al into the Fe₇₃Ga₂₇ and (Fe₇₃Ga₂₇)_99.9La_0.1 alloy, respectively. The results show that both the Fe₇₃Ga_27−xAl_x alloy and (Fe₇₃Ga_27−xAl_x)_99.9La_0.1 alloy are dominated by the A2 phase, and the alloy grains are obvious columnar crystals with certain orientations along the water-cooled direction. A proportion of Al atoms replaced Ga atoms, which changed the lattice constant of the alloy, caused lattice distortion, and produced vacancy effects which affected the magnetostriction properties. La atoms were difficult to dissolve in the matrix alloy which made the alloy grains smaller and enhanced the orientation along the (100) direction, resulting in greater magneto-crystalline anisotropy and greater tetragonal distortion, which is conducive to improving the magnetostriction properties. Fe₇₃Ga_24.5Al_2.5 alloy has a saturation magnetostrictive strain of 74 ppm and a hardness value of 268.064 HV, taking into account the advantages of saturated magnetostrictive strain and high hardness. The maximum saturation magnetostrictive strain of the (Fe₇₃Ga_24.5Al_2.5)_99.9La_0.1 alloy is 115 ppm and the hardness is 278.096 HV, indicating that trace La doping can improve the magnetostriction properties and deformation resistance of Fe-Ga alloy, which provides a new design idea for the Fe-Ga alloy, broadening their application in the field of practical production. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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