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A finite oxidation strategy for customizing heterogeneous interfaces to enhance magnetic loss ability and microwave absorption of Fe-cored carbon microcapsules

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Nano Research 2023年第8期16卷 11084-11095页

作者： Meixi Zhang Laisen Wang Susu Bao Zhijia Song Wenjiao Chen Zhiyuan Jiang Zhaoxiong Xie Lansun Zheng State Key Laboratory for Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China College of Materials Xiamen UniversityXiamen 361005China

Metallic iron particles are of great potential for microwave absorption materials due to their strong magnetic loss ability.However,the oxidation susceptibility of metallic iron particles in the atmospheric environment is regarded as a major factor causing performance degradation.Although many efforts have been developed to avoid their oxidation,whether partial surface oxidized iron particles can improve the microwave absorbing performance is rarely concerned.In order to explore the effect of partial surface oxidation of iron on its properties,the designed yolk–shelled(Fe/FeO_(x))@C composites with multiple heterointerfaces were synthesized via an in-situ polymerization and a finite reduction–oxidation process of Fe_(2)O_(3)ellipsoids.The performance enhancement mechanisms of Fe/FeO_(x)heterointerfaces were also elaborated.It is demonstrated that the introduction of Fe-based heterogeneous interfaces can not only enhance the dielectric loss,but also increase the imaginary part of the permeability in the higher frequency range to strengthen the magnetic loss ability.Meanwhile,the yolk–shell structure can effectively improve impedance matching and enhance microwave absorption performances via increasing multiple reflection and scattering behaviors of incident microwaves.Compared to Fe@C composite,the effective absorption(reflection loss(RL)magnetic loss ability and microwave absorption performance of Fe-based microwave absorption materials with promising practical applications.

关键词： heterogeneous interfaces finite oxidation yolk-shell structure magnetic loss interface polarization microwave absorption

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Hysteresis loss reduction in self-bias FeSi/SrFe_(12)O_(19)soft magnetic composites

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Chinese Physics B 2022年第2期31卷 576-580页

作者：冯双久倪江利胡锋阚绪材吕庆荣刘先松 Engineering Technology Research Center of magnetic Materials of Anhui Province School of Physics and Materials ScienceAnhui UniversityHefei 230601China Engineering Technology Research Center of Preparation and Application of Industrial Ceramics of Anhui Province School of Chemistry and Material EngineeringChaohu UniversityHefei 238000China

The magnetic field provided by magnetized SrFe_(12)O_(19)particles in FeSi/SrFe_(12)O_(19)composites is used to replace the applied transverse magnetic field,which successfully reduces the magnetic loss of the composites with minor reduction of permeability.This magnetic loss reduction mainly comes from the decrease in hysteresis loss,while the eddy current loss is basically unaffected.The hysteresis loss reduction in magnetized composites is believed to be due to the decrease in domain wall displacement caused by the increase in the average magnetic domain size in a DC magnetic field.This is an effective method for reducing the magnetic loss of soft magnetic composites with wide application potential,and there is no problem of increasing the cost and the volume of the magnetic cores.

关键词： soft magnetic composites FeSi SrFe_(12)O_(19) magnetic loss

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Evolution of dielectric loss-dominated electromagnetic patterns in magnetic absorbers for enhanced microwave absorption performances

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Nano Research 2021年第11期14卷 4006-4013页

作者： Xiaogu Huang Man Qiao Xiaochi Lu Yafei Li Yabin Ma Bo Kang Bin Quan Guangbin Ji Institute of Advanced Materials and Flexible Electronics(IAMFE) School of Chemistry and Materials ScienceNanjing University of Information Science&TechnologyNanjing210044China College of Electronic and Optical Engineering&College of Microelectronics Nanjing University of Posts and TelecommunicationsNanjing210023China Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials School of Chemistry and Materials ScienceNanjing Normal UniversityNanjing210023China College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing211100China

As the growing criterion of electromagnetic wave (EMW) absorption materials, micro/nano-scale magnetic materials are drawing more and more attention for their unique features compared to bulky absorbers. Generally, the complex permeability of micro/nano-scale magnetic absorbers varies in a relatively narrow range, whatever for the storage of magnetic energy or the dissipation of magnetic energy. If so, how the small variation of permeability affects the ultimate performances is still unclear. Here, a strategy of electromagnetic parameters regulation for the magnetic materials is applied to understand the loss contribution in micro/nanoscale magnetic absorbers. After analyzing the evolution of electromagnetic maps of ten ferrosoferric oxide samples, it can be found that the dissipation contribution of permeability for magnetic materials is weaker than that of permittivity, in spite of its significant role in determining the impedance matching characteristics. In summary, this work systematically explores the loss contribution in micro/nano-magnetic absorbers for the first time, which is of great importance in designing and optimizing the microwave absorption properties of magnetic absorbers.

关键词： dielectric loss magnetic loss impedance matching geometric interference microwave absorption

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Finite Element CAD Experiments on the Effect of magnetic loss in Power Transformers with Laminated Cores

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Journal of Electromagnetic Analysis and Applications 2021年第1期13卷 1-19页

作者： Antônio Flavio Licarião Nogueira Rodolfo Lauro Weinert Leonardo José Amador Salas Maldonado Department of Electric Engineering Santa Catarina State University Joinville Santa Catarina Brazil

The paper describes a simulated experiment that focuses on the numeric computation of magnetic loss in the laminated core of a single-phase power transformer. The students’ laboratory work is part of the library of experiments of the Electrical Machines virtual laboratory and makes use of the two-dimensional open-access electromagnetic field analysis software Finite Element Method magnetics. The idea of the simulated exercise is to demonstrate how the magnetic loss caused by time-varying excitations affects the magnetic permeability, μ, of the laminated core and the terminal quantities of the energizing winding. A parametric analysis employing different values for the electrical conductivity and maximum hysteresis-induced angle of the laminated material yields five different field problems with increasing magnetic loss. Electric circuits characterized by the (I-V) operating point and reflected impedance of the energizing winding provide the information required to compute the changes in real power ΔP, reactive power ΔQ and magnetically stored energy ΔWm between successive problems characterized by increasing magnetic loss. The concept of reflected impedance helps to explain the physical meaning of the changes in power dissipation and energy storage in the laminated core.

关键词： Eddy Currents Electromagnetic Engineering Education Finite Element Analysis Hysteresis magnetic loss Transformer Cores

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Macroscopic electromagnetic synergy network-enhanced N-doped Ni/C gigahertz microwave absorber with regulable microtopography

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Nano Research 2023年第7期16卷 10666-10677页

作者： Yuelei Pan Qianqian Zhu Jiahui Zhu Yuhang Cheng Bowen Yu Zirui Jia Guanglei Wu Institute of Materials for Energy and Environment State Key Laboratory of Bio-fibers and Eco-textilesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071China College of Chemistry and Chemical Engineering Qingdao UniversityQingdao 266071China

To achieve excellent electromagnetic wave(EMW)absorption properties,the microstructure design of the absorber is critical.In this work,six kinds of N-Ni/C nanostructures with different morphologies were prepared by one-step hydrothermal method and high temperature carbonization by adjusting the types of nickel salts and reaction solvents.The EMW absorption performance of six different morphologies of N-Ni/C nanostructures was compared and analyzed.Among them,it is found that the nanoflowerlike N-Ni/C composite has excellent dielectric loss and magnetic loss synergistic effect due to its polycrystalline structure,and can obtain excellent EMW absorption performance.The minimum reflection loss value at a thickness of 1.9 mm is-59.56 dB at 16.88 GHz,and the effective absorption bandwidth value reaches 6.0 GHz at a thickness of 2.2 mm.Our research shows that different morphologies and multiple lattice structures of nanostructures with the same composition have a significant influence on EMW absorption performance,which provides new research ideas for developing high-performance EMW absorbing materials.

关键词： magnetic metal-carbon binary composition morphology control dielectric loss magnetic loss electromagnetic wave absorption

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Lightweight,self-cleaning and refractory FeCo@MoS_(2)PVA aerogels:from electromagnetic wave-assisted synthesis to flexible electromagnetic wave absorption

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Rare Metals 2023年第4期42卷 1294-1305页

作者： Sai-Bo Qian Guang Liu Mi Yan Chen Wu School of Materials Science and Engineering State Key Laboratory of Silicon MaterialsZhejiang UniversityHangzhou310027China

The emergence of wearable and foldable electronic devices urges advanced electromagnetic(EM)wave absorbers with maintained performance under deformation.Here FeCo@MoS_(2)poly vinyl alcohol(PVA)aerogels have been fabricated with the assistance of EM waves for simultaneous splitting of the MoS_(2)flakes and dispersive growth of FeCo nanoparticles.The resultants in-return have been used for EM wave absorption with excellent performance,providing minimum reflection loss(RL_(min))of-40.7 dB and a broad effective absorption bandwidth(EAB)of 6.4 GHz at a thickness of 2.5 mm.Real-time compression has been introduced to reveal the evolution of EM parameters.The aerogels maintain satisfactory performance even under 50%compression due to the balance of impedance matching and attenuation.Despite the deterioration of impedance matching,the attenuation is significantly enhanced due to both strengthened conductive loss and magnetic loss.In addition,features such as lightweight,self-cleaning and refractory can be achieved for the aerogels for applications in complex environments.As such this work not only provides a versatile synthetic route assisted by EM wave energy,but also insights on the evolution of absorption performance under deformation together with the design strategy of multifunctional flexible wave absorbers.

关键词： Electromagnetic(EM)wave assistance Multifunctional aerogels Deformative wave absorption Impedance matching Conductive loss magnetic loss

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In-situ grown Ni Co bimetal anchored on porous straw-derived biochar composites with boosted microwave absorption properties

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International Journal of Minerals,Metallurgy and Materials 2023年第3期30卷 515-524页

作者： Yuanyuan Zhou Zhongyi Bai Xiangyang Yang Wei Liu Bingbing Fan Zhikai Yan Xiaoqin Guo Henan Key Laboratory of Aeronautical Materials and Application Technology School of Material Science and EngineeringZhengzhou University of AeronauticsZhengzhou 450046China School of Chemical&Environmental Engineering China University of Mining&Technology(Beijing)Beijing 100083China School of Material Science and Engineering Zhengzhou UniversityZhengzhou 450001China

With the gradually increasing protection awareness about electromagnetic pollution,the demand for absorbing materials with renewability and environmental friendliness has attracted widespread attention.In this work,composites consisting of straw-derived biochar combined with NiCo alloy were successfully fabricated through high-temperature carbonization and subsequent hydrothermal reaction.The electromagnetic parameters of the porous biocarbon/NiCo composites can be effectively modified by altering their NiCo content,and their improved absorbing performance can be attributed to the synergy effect of magnetic-dielectric characteristics.An exceptional reflection loss of-27.0 dB at 2.2 mm thickness and an effective absorption bandwidth of 4.4 GHz(11.7-16.1 GHz)were achieved.These results revealed that the porous biocarbon/NiCo composites could be used as a new generation absorbing material because of their low density,light weight,excellent conductivity,and strong absorption.

关键词： straw-derived biochar microwave absorption interfacial polarization magnetic loss bimetallic NiCo impedance matching

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High-entropy spinel ferrites MFe_(2)O_(4)(M=Mg,Mn,Fe,Co,Ni,Cu,Zn)with tunable electromagnetic properties and strong microwave absorption

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Journal of Advanced Ceramics 2022年第5期11卷 754-768页

作者： Jiabin MA Biao ZHAO Huimin XIANG Fu-Zhi DAI Yi LIU Rui ZHANG Yanchun ZHOU Henan Key Laboratory of Aeronautical Materials and Application Technology School of Materials Science and EngineeringZhengzhou University of AeronauticsZhengzhou 450046China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China School of Material Science and Engineering Shaanxi University of Science and TechnologyXi'an 710021China School of Materials Science and Engineering Luoyang Institute of Science and TechnologyLuoyang 471023China

Ferrites are the most widely used microwave absorbing materials to deal with the threat of electromagnetic(EM)pollution.However,the lack of sufficient dielectric loss capacity is the main challenge that limits their applications.To cope with this challenge,three high-entropy(HE)spineltype ferrite ceramics including(Mg_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2))Fe_(2)O_(4),(Mg_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2)Cu_(0.2))Fe_(2)O_(4),and(Mg_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2)Zn_(0.2))Fe_(2)O_(4)were designed and successfully prepared through solid state synthesis.The results show that all three HE MFe_(2)O_(4) samples exhibit synergetic dielectric loss and magnetic loss.The good magnetic loss ability is due to the presence of magnetic components;while the enhanced dielectric properties are attributed to nano-domain,hopping mechanism of resonance effect and HE effect.Among three HE spinels,(Mg_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2))Fe_(2)O_(4)shows the best EM wave absorption performance,e.g.,its minimum reflection loss(RL_(min))reaches-35.10 dB at 6.78 GHz with a thickness of 3.5 mm,and the optimized effective absorption bandwidth(EAB)is 7.48 GHz from 8.48 to 15.96 GHz at the thickness of 2.4 mm.Due to the easy preparation and strong EM dissipation ability,HE MFe_(2)O_(4) are promising as a new type of EM absorption materials.

关键词： high-entropy ceramics(HECs) spinel-type ferrite electromagnetic(EM)wave absorption dielectric loss magnetic loss

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Anionic MOF derived Bimetallic Ni_(x)Co_(y)@Nano-porous carbon composites toward strong and efficient electromagnetic wave absorption

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Journal of Materiomics 2022年第4期8卷 852-862页

作者： Fan Zhang Yefu Chen Yujie Ren Qi Zheng Lianjun Wang Wan Jiang State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and EngineeringDonghua UniversityShanghai201620China Engineering Research Center of Advanced Glasses Manufacturing Technology Ministry of EducationDonghua UniversityShanghai201620China Institute of Functional Materials Donghua UniversityShanghai201620China

Metal-organic frameworks (MOFs) derived metallic nanoparticles embedded nano-porous carbon (NPC)composites have shown to be promising microwave absorbing materials. Although MOF precursors withdiverse compositions and morphologies have been extensively investigated, anionic MOFs are rarelyexplored for this utility. In addition to the metal sites and ligands on the MOF framework, the guestcounter-cations in the void provide supplementary parameters to tune the capability of microwaveabsorption. Herein, we applied an anionic NixCoy-MOF featuring N-rich ligands and hierarchical porousstructures as a precursor for microwave absorption. The obtained dielectric-magnetic Ni_(x)Co_(y)@NPCcomposites with rich N dopants and multiple hetero-interfaces promote the microwave attenuationcapability through enhanced dipole/interfacial relaxation. The synergistic effects of magnetic loss andconduction loss induced by metallic nanoparticles (NPs) and porous graphitic layers further facilitate themicrowave dissipation. More significantly, impedance matching can be effectively improved by tuningthe Co/Ni amount in the precursors to realize the modulation of electromagnetic parameters. Conse-quently, Ni@NPC exhibits the optimal electromagnetic wave (EMW) absorption with minimum reflectionloss of 66 dB at only 2 mm and broad effective absorption band covering 4.56 GHz at a thin thickness of2.07 mm, making this material promising absorber for EMW elimination.

关键词： Anionic MOFs MOF-Derived carbon composites N-rich ligands Dielectric loss magnetic loss Electromagnetic wave absorption

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Rational construction of graphene oxide with MOF- derived porous NiFe@C nanocubes for high-performance microwave attenuation

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Nano Research 2016年第12期9卷 3671-3682页

作者： Zhihong Yang Hualiang Lv Renbing WU College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 211100 China Department of Materials Science Fudan University Shanghai 200433 China

Exploring lightweight microwave attenuation materials with strong and tunable wideband microwave absorption is highly desirable but remains a significant challenge. Herein, three-dimensional （3D） porous hybrid composites consisting of NiFe nanoparticles embedded within carbon nanocubes decorated on graphene oxide （GO） sheets （NiFe@C nanocubes@GO） as high-performance microwave attenuation materials have been rationally synthesized. The 3D porous hybrid composites are fabricated by a simple method, which involves one-step pyrolysis of NiFe Prussian blue analogue nanocubes in the presence of GO sheets. Benefiting from the unique structural features that exhibit good magnetic and dielectric losses as well as a proper impedance match, the resulting NiFe@C nanocubes@GO composites show excellent microwave attenuation ability. With a minimum reflection loss （RL） of -51 dB at 7.7 GHz at a thickness of 2.8 mm and maximum percentage bandwidth of 38.6% for RL 〈 -10 dB at a thickness of 2.2 mm, the NiFe@C nanocubes@GO composites are superior to the previously reported state-of-the-art carbon-based microwave attenuation materials.

关键词： hybrid dielectric loss magnetic loss microwave attenuation

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