Facial Synthesis of Zn-Doped Fe3O4 with Enhanced Electromagnetic Wave Absorption Performance in S and C Bands

In this study, Zn-doped Fe3O4 nanoparticles were successfully synthesized by a facile solvothermal method in the presence of sodium dodecyl sulfate (SDS). The morphology, magnetic properties and electromagnetic wave absorbing properties of these materials were characterized. Results showed that Zn[Formula: see text] played a significant role in the formation of Zn-doped Fe3O4. With the protection of SDS, highly dispersed Fe3O4 nanoparticles were obtained. The nanoparticle size decreased after Zn[Formula: see text] doping, and the dispersity deteriorated with increasing Zn[Formula: see text] doping concentration. Zn-doped Fe3O4 exhibited excellent electromagnetic wave absorbing property, which resulted in magnetic loss and dielectric loss at an appropriate doping concentration. The minimum reflection loss (RL) was approximately [Formula: see text][Formula: see text]dB at 16.9[Formula: see text]GHz. As the coating layer thickness increased to 4.0[Formula: see text]mm, the bandwidth was approximately 5.0[Formula: see text]GHz corresponding to RL below [Formula: see text][Formula: see text]dB, which nearly covered the entire S band (2–4[Formula: see text]GHz) and C band (4–8[Formula: see text]GHz). The peak frequency of RL and the number of peaks matched the quarter-wave thickness criteria. It was believed that the Zn-doped Fe3O4 could be a potential electromagnetic wave absorbing material in S and C bands.

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The Electromagnetic Wave Absorption Performance and Mechanical Properties of Cement-Based Composite Material Mixed with Functional Aggregates with High Fe2O3 and SiC

Revue des composites et des matériaux avancés ◽

10.18280/rcma.310409 ◽

2021 ◽

Vol 31 (4) ◽

pp. 249-255

Author(s):

Zuoqun Zhang ◽

Chaoshan Yang ◽

Hua Cheng ◽

Xiaohan Huang ◽

Yuhao Zhu

Keyword(s):

Composite Material ◽

Electromagnetic Wave ◽

Electromagnetic Waves ◽

Building Materials ◽

Magnetic Loss ◽

Frequency Range ◽

Electromagnetic Wave Absorption ◽

Wave Absorption ◽

Test Board ◽

Absorption Performance

Now there’re many researches on the electromagnetic radiation protection function of the cement-based electromagnetic wave absorbing materials, such materials have been widely used in various types of buildings. This paper proposed an idea for preparing a cement-based composite material by mixing functional aggregates with high content of Fe2O3 and SiC, that is, adding Fe3O4 powder and nano-SiC of different contents in the clay, and then sintering at 1190℃; the prepared aggregates showed obvious magnetic loss and dielectric loss to electromagnetic waves, and the numerical tube pressure could reach 16.83MPa. The double-layer reflectivity test board made of functional aggregates showed excellent electromagnetic wave absorption performance, its reflection loss was less than -10dB in the frequency range of 8~18GHz (corresponding to energy absorption greater than 90% EM), and its maximum RL reached -12.13dB. In addition, the compressive strength of the cement-based composite material at the age of 28 days reached 50.1 MPa, which can meet the strength requirements of building materials.

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Fabrication of Electrospun Ni0.5Zn0.5Fe2O4 Nanofibers Using Polyvinyl Pyrrolidone Precursors and Electromagnetic Wave Absorption Performance Improvement

Polymers ◽

10.3390/polym13234247 ◽

2021 ◽

Vol 13 (23) ◽

pp. 4247

Author(s):

Kyeong-Han Na ◽

Kyong-Pil Jang ◽

Sung-Wook Kim ◽

Won-Youl Choi

Keyword(s):

Electromagnetic Wave ◽

Return Loss ◽

Magnetic Loss ◽

Average Diameter ◽

Electromagnetic Properties ◽

X Ray Diffraction ◽

Loss Mechanism ◽

X Ray ◽

Line Theory ◽

Absorption Performance

Ni0.5Zn0.5Fe2O4 nanofibers with an average diameter of 133.56 ± 12.73 nm were fabricated by electrospinning and calcination. According to our thermogravimetric—differential thermal analysis and X-ray diffraction results, the calcination temperature was 650 °C. The microstructure, crystal structure, and chemical composition of the nanofibers were observed using field-emission scanning electron, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Commercial particle samples and samples containing 10 wt% and 20 wt% nanofibers were fabricated, and the electromagnetic properties were analyzed with a vector network analyzer and a 7.00 mm coaxial waveguide. Regardless of the nanofiber content, Ni0.5Zn0.5Fe2O4 was dominantly affected by the magnetic loss mechanism. Calculation of the return loss based on the transmission line theory confirmed that the electromagnetic wave return loss was improved up to −59.66 dB at 2.75 GHz as the nanofiber content increased. The absorber of mixed compositions with Ni0.5Zn0.5Fe2O4 nanofibers showed better microwave absorption performance. It will be able to enhance the performance of commercial electromagnetic wave absorbers of various types such as paints and panels.

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Electromagnetic Wave Absorption and Mechanical Properties of CNTs@GN@Fe3O4/PU Multilayer Composite Foam

Materials ◽

10.3390/ma14237244 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7244

Author(s):

Chunfu Gao ◽

Xinsheng He ◽

Fengchao Ye ◽

Shuxin Wang ◽

Guang Zhang

Keyword(s):

Carbon Nanotubes ◽

Electromagnetic Wave ◽

Carbon Nanomaterials ◽

Magnetic Loss ◽

Effective Bandwidth ◽

Electromagnetic Wave Absorption ◽

Wave Absorption ◽

Field Of Vision ◽

Layer Composite ◽

Absorbing Material

With the development of intelligent communications and stealth technology in the military field, electromagnetic wave pollution cannot be ignored, and absorbing materials have entered people’s field of vision and gradually become a research hotspot. The ideal absorbing material should have the characteristics of “strong, wide, thin, and light”, but a single absorbing material often cannot meet the above conditions. At present, absorbing metal powder combined with two-dimensional carbon nanomaterials (such as carbon nanotubes, graphene, etc.) has became a trend. This article focus on a three-layer composite of Fe3O4, Carbon nanotubes@ Fe3O4, Carbon nanotubes@Graphene nano-platelets@ Fe3O4, which was synthesized by solvothermal method. The results show that the electromagnetic wave absorption performance of the three-layer foam at a thickness of 3.0 mm is more excellent. The minimum of RL can reach −67.0 dB, and the effective bandwidth is above 5.0 GHz. All this is due to the synergy of dielectric and magnetic loss between Fe3O4, CNTs, and GN, the increase of interface polarization and the path of electromagnetic wave reflection and scattering by three-layer foam.

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Core–Shell Structural Barium Ferrite/Polypyrrole Nanocomposites with Enhanced Microwave Absorption Properties

Journal of Nanoelectronics and Optoelectronics ◽

10.1166/jno.2020.2856 ◽

2020 ◽

Vol 15 (11) ◽

pp. 1312-1320

Author(s):

Kai Sun ◽

Gang Li ◽

Yan-Hua Lei ◽

Xin-Feng Wu ◽

Wei-Guo Zhang ◽

...

Keyword(s):

Electromagnetic Wave ◽

Microwave Absorption ◽

Barium Ferrite ◽

Wave Attenuation ◽

Magnetic Loss ◽

Impedance Matching ◽

Oxidative Polymerization ◽

Electromagnetic Properties ◽

Core Shell ◽

Absorption Performance

In this paper, core–shell structural barium ferrite/polypyrrole (BF/PPy) nanocomposites were prepared by a facile in-situ chemical oxidative polymerization method, and their electromagnetic properties were systematically studied. It was demonstrated that the nanocomposites with 15 mol% BF possessed the best electromagnetic wave absorption performance, and a reflection loss of -57.13 dB was achieved at 3.98 mm. Further study revealed that the optimized impedance matching and large attenuation constant were conducive to a good absorption performance. Meanwhile, the combined action of dielectric loss and magnetic loss was responsible for the electromagnetic wave attenuation. This study provides a supplementary approach to microwave absorption materials with a desirable absorption performance.

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