scholarly journals Microwave Absorption Properties of Fe3O4 Particles Coated with Al via Rotating Magnetic Field Method

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 621
Author(s):  
Ivan Shorstkii ◽  
Maxim Sosnin
Keyword(s):  
Magnetic Field ◽  
Microwave Absorption ◽  
Magnetic Loss ◽  
Field Method ◽  
Wide Frequency Range ◽  
Rotating Magnetic Field ◽  
Absorption Properties ◽  
Magnetic Composites ◽  
Microwave Absorption Properties ◽  
Al Nanoparticles

Soft magnetic composites (SMCs) of Fe3O4 particles coated with Al nanoparticles were prepared using the rotating magnetic field method, and the microwave absorption properties and microstructures of these composites were investigated. The results show that a well-distributed Al nanoparticles coating layer was formed on the surface of the Fe3O4 particles upon mechanical friction and rotating magnetic field distribution. Scanning electron microscopy SEM and X-ray diffraction XRD studies show that the rotating magnetic field method can produce a uniform coating of the aluminium layer on the Fe3O4 particles. Compared with common composites from Fe3O4 particles, SMCs of Fe3O4(Al) particles have stronger magnetic loss behaviour and weaker dielectric loss ability, as well as good reflection characteristics over a wide frequency range. The minimum reflection loss (RL) is −16.2 dB at 12.0 GHz for a corresponding thickness of 5 mm obtained for SMCs of Fe3O4(Al) particles. The presented rotating magnetic field method used in the Fe3O4 particles coating process with Al nanoparticles has great potential in composite materials synthesis with different morphology and areas of application.

scholarly journals Microwave Absorption Properties of Magnetite Particles Extracted from Nickel Slag

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2162
Author(s):  
Pengze Yan ◽  
Yongqian Shen ◽  
Xueyan Du ◽  
Junkai Chong
Keyword(s):  
Electron Microscopy ◽  
Ball Milling ◽  
Microwave Absorption ◽  
Photoelectron Spectroscopy ◽  
Magnetic Loss ◽  
Interfacial Polarization ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Transmission Electron

The utilization of nickel slag has attracted much attention due to its high-content of valuable elements. As a part of these efforts, this work focuses on whether magnetite crystals, obtained from nickel slag via molten oxidation, magnetic separation, and ball-milling can be used as a microwave absorber. The composition, morphology, microstructure, magnetic properties, and microwave absorption performance were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and vector network analysis (VNA). The results reveal that the magnetite crystals exhibit excellent microwave absorption properties because of the synergistic action between dielectric loss and magnetic loss. The minimum reflection loss (RL) of the particles obtained after 6 h ball-milling reaches −34.0 dB at 16.72 GHz with thickness of 5 mm. The effective frequency bandwidth (RL ≤ −10 dB) is 4.8–5.4 GHz and 15.9–17.6 GHz. Interfacial polarization of the particles could play a crucial role in improving absorbing properties because several components contained in the particles can dissipate electromagnetic wave effectively. The current study could show great potential in the preparation of magnetite crystals and utilization of nickel slag.

Fabrication and Microwave Characteristics of Fe3O4/C Composites

2012 ◽  
Vol 430-432 ◽  
pp. 146-149 ◽  
Author(s):  
Wen Wang ◽  
Cheng Guo Wang ◽  
Yu Guo
Keyword(s):  
Microwave Absorption ◽  
Magnetic Loss ◽  
Carbon Matrix ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Heat Treated ◽  
Different Temperatures ◽  
Microwave Characteristics

Fe3O4/C composites were prepared by using Fe and polyacrylonitrile (PAN) as precursors, and then heat-treated at temperatures of 600,700 and 800 °C, respectively. The phase composition of the composites at different temperatures was analyzed by X-ray diffraction, and Fe reacted with O from PAN to form Fe3O4, which contributed to the improvement of magnetic loss of the carbon matrix. Electromagnetic and microwave absorption properties of the composites were investigated. The results show that the values of real and imaginary part of permittivity were all increased as the temperature increasing, and also the microwave absorption capability was improved.

scholarly journals Preparation and Microwave Absorption Properties of C@Fe3O4 Magnetic Composite Microspheres

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2404
Author(s):  
Youqiang Shi ◽  
Yanan Yin ◽  
Yi Zhang ◽  
Yue Hu ◽  
Weifeng Liu
Keyword(s):  
Microwave Absorption ◽  
Magnetic Loss ◽  
Magnetic Microspheres ◽  
Effective Bandwidth ◽  
Magnetic Composite ◽  
Absorption Properties ◽  
Particle Size Range ◽  
Carboxyl Content ◽  
Microwave Absorption Properties ◽  
Fe3o4 Microspheres

In this work, C@Fe3O4 magnetic microspheres were designed and prepared by a novel strategy, and the microwave absorption properties of the materials were investigated. Four kinds of monodisperse P(MAA/St) microspheres with different carboxyl content were synthesized via facile dispersion polymerization. The Fe3O4 nanoparticles were grown on the surface of P(MAA/St) to obtain P(MAA/St)@Fe3O4 microspheres. Using P(MAA/St)@Fe3O4 as the precursors, after vacuum carbonization, C@Fe3O4 were obtained. It was observed that the carboxyl content on the microspheres’ surface increased with the increasing of MAA, which made the magnetic content and maximum specific saturation magnetization of P(MAA/St)@Fe3O4 and C@Fe3O4 increase. The obtained four kinds of C@Fe3O4 microspheres had a particle size range of 4–6 μm. The microwave absorption properties indicated that the magnetic content made a difference to the microwave absorption properties of C@Fe3O4 magnetic microspheres. The microwave absorption properties of materials were determined by controlling dielectric loss, magnetic loss and impedance matching. C@Fe3O4 microspheres exhibited excellent microwave absorption properties. The maximum reflection loss could reach −45.6 dB at 12.8 GHz with 3 mm in thickness. The effective bandwidth was 5.9 GHz with RL < −10 dB. Therefore, C@Fe3O4 microspheres were lightweight and efficient microwave absorption materials.

Preparation and Electromagnetic Wave Absorption Properties of Core-Shell Ni/TiO2 Microspheres

2014 ◽  
Vol 602-603 ◽  
pp. 762-766
Author(s):  
Biao Zhao ◽  
Bing Bing Fan ◽  
Hao Chen ◽  
Xiao Xuan Pian ◽  
Bin Bin Wang ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Microwave Absorption ◽  
Magnetic Loss ◽  
Core Shell ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Electromagnetic Wave Absorption ◽  
X Ray ◽  
Wave Absorption ◽  
Chloride Hexahydrate

The composite microspheres with Ni cores and amorphous TiO2 shells (Ni@TiO2) were synthesized by a one-pot solvothermal method at 180°C for 15 h, which used nickel chloride hexahydrate as Ni source andtetrabutyl orthotitanate as Ti source. The Ni/TiO2 core/shell composites were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX). A possible formation mechanism of core-shell Ni/TiO2 was proposed. Furthermore, the microwave absorption properties of these microspheres were investigated in terms of complex permittivity and permeability. The minimum reflection loss is-29.5 dB at 14.4 GHz for a layer of 4.0 mm thickness. Such phenomenon is attributed to the synergy effect between magnetic loss of Ni core and dielectric loss of amorphous TiO2 shell. The enhanced microwave absorption properties are also believed to be due to the unique coreshell structure. All results indicate that these Ni@TiO2 microspheres may be attractive candidate materials for electromagnetic wave absorption applications.

Microwave Absorption Properties of Fe3O4-Graphene Nanohybrids

2017 ◽  
Vol 268 ◽  
pp. 297-301 ◽  
Author(s):  
Yau Thim Ng ◽  
Wei Kong ◽  
Sivanesan Appadu ◽  
Ing Kong
Keyword(s):  
Microwave Absorption ◽  
Magnetic Loss ◽  
Impedance Matching ◽  
Low Frequency ◽  
Electromagnetic Properties ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
In Situ Deposition

Magnetite (Fe3O4)-graphene nanohybrids having three different weight ratios of magnetite to graphene were synthesized by a facile in-situ deposition method. The combination of dielectric properties of graphene and magnetic properties of magnetite makes the nanohybrids an ideal choice of material for microwave absorption applications. In regards to that, the electromagnetic properties and microwave absorbing characteristics were investigated in a frequency range of 1-18 GHz. The reflection loss (RL) reaches a minimum of-40.44 dB at 6.84 GHz with a thickness of 7 mm for the sample containing 73 wt·% of Fe3O4. The bandwidth corresponding to the RL below-10 dB is 7.05 GHz. The as-prepared Fe3O4-graphene nanohybrids showed good microwave absorption ability in the low frequency band (C-band) which can be ascribed to improved impedance matching characteristics, enhanced interfacial polarizations as well as the magnetic loss contributions. Moreover, the frequency related to minimum RL could be tuned by varying the weight ratios of magnetite to graphene.

Microwave Absorption Properties of Monovalent Doped La0.85Ag0.15MnO3 Manganites Prepared by Solid State Method

2021 ◽  
Vol 317 ◽  
pp. 22-27
Author(s):  
Nur Ain Athirah Che Apandi ◽  
Norazila Ibrahim ◽  
Zaiki Awang ◽  
Ra'ba'ah Syahidah Azis ◽  
Muhammad Syazwan Mustaffa ◽  
...  
Keyword(s):  
Solid State ◽  
Microwave Absorption ◽  
Reflection Loss ◽  
Magnetic Loss ◽  
Domain Wall Motion ◽  
Rhombohedral Structure ◽  
Absorption Properties ◽  
Solid State Method ◽  
Microwave Absorption Properties ◽  
State Method

The microwave absorption properties of La0.85Ag0.15MnO3 prepared by solid state method was investigated. Analysis of X-ray diffraction data using a refinement technique confirmed the rhombohedral structure of the samples. The microstructure of the sample characterised from field emission scanning electron microscope micrographs showed irregular grain shapes with grain sizes ranging from 800 to 1500 nm. M-H curves revealed the weak ferromagnetic properties of the sample at room temperature. The real and imaginary parts of permittivity and permeability as well as microwave reflection loss were measured by a vector network analyser in the 8–18 GHz frequency range. The La0.85Ag0.15MnO3 sample showed a minimum reflection loss of –57.2 dB at 16.41 GHz, with a –10dB bandwidth (corresponding to reflection loss below –10 dB, or 90% absorption) of 2.67 GHz. The microwave absorption of La­­­­0.85Ag0.15MnO3 mainly arises from the conduction loss and domain wall motion which contributed to dielectric loss and magnetic loss, respectively.

scholarly journals Influence of External Magnetic Field on the Microwave Absorption Properties of Carbonyl Iron and Polychloroprene Composites Film

2016 ◽  
Author(s):  
Haiyan Wang ◽  
Xueai Li
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Microwave Absorption ◽  
Reflection Loss ◽  
Carbonyl Iron ◽  
Magnetic Particles ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Line Theory ◽  
Composites Film

The carbonyl iron particles were dispersed in a polychloroprene rubber (CR) matrix under an external magnetic field for practical application as microwave absorption composites film. The film prepared under external magnetic field with a thickness of only 0.54 mm showed least reflection loss of -15.98 dB and the reflection loss value less than -10.0 dB over the frequency range of 11.4~14.8 GHz. In comparison with the microwave absorption properties of calculation by transmission line theory based on the tested relative complex permittivity and permeability and film prepared by general route without external magnetic field, the film made with external magnetic field exhibited more excellent microwave absorption properties, strongly depending on the increment of anisotropy and rearrangement of magnetic particles. The results indicated the composite film made under external magnetic field have excellent microwave absorption properties, which suggest that the composites thin film could be used as a thinner and lighter microwave absorber.

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