scholarly journals Microstructural Design of Necklace-Like Fe3O4/Multiwall Carbon Nanotube (MWCNT) Composites with Enhanced Microwave Absorption Performance

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4783
Author(s):  
Mu Zhang ◽  
Sinan Song ◽  
Yamin Liu ◽  
Zaoxia Hou ◽  
Wenyi Tang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Microwave Absorption ◽  
Impedance Matching ◽  
Interfacial Polarization ◽  
Carbon Matrix ◽  
Thermal Method ◽  
Multiwall Carbon Nanotube ◽  
Matrix Composites ◽  
Experimental Parameters ◽  
Absorption Performance

In order to manufacture microwave absorbers with strong attenuation abilities and that are light weight, in this paper, ferromagnetic carbon matrix composites were prepared by the composite of carbon nanotubes with adjustable dielectric constant and Fe3O4. Fe3O4/MWCNT composites with well-designed necklace-like structure and controllable size in the range of 100–400 nm have been successfully achieved by a simple solvent thermal method. A series of samples were prepared by changing experimental parameters. The microwave absorption characteristics of these samples were studied from the dielectric constant and magnetic permeability in two aspects. The electromagnetic absorption properties of the composites show obvious differences with different microsphere sizes, different microsphere density and different proportion of additives. When the solvothermal time is 15 h and the microsphere size is 400 nm, the reflection loss reaches −38 dB. The interfacial polarization caused by the unique structural design and good impedance matching produce composites that possess excellent electromagnetic loss ability.

scholarly journals Tuning Dielectric Loss of SiO2@CNTs for Electromagnetic Wave Absorption

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2636
Author(s):  
Fenghui Cao ◽  
Jia Xu ◽  
Xinci Zhang ◽  
Bei Li ◽  
Xiao Zhang ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
High Performance ◽  
Low Cost ◽  
Impedance Matching ◽  
3D Structure ◽  
Carbon Matrix ◽  
Current Approach ◽  
Matrix Composites ◽  
Simple Method ◽  
Absorption Performance

We developed a simple method to fabricate SiO2-sphere-supported N-doped CNTs (NCNTs) for electromagnetic wave (EMW) absorption. EMW absorption was tuned by adsorption of the organic agent on the precursor of the catalysts. The experimental results show that the conductivity loss and polarization loss of the sample are improved. Meanwhile, the impedance matching characteristics can also be adjusted. When the matching thickness was only 1.5 mm, the optimal 3D structure shows excellent EMW absorption performance, which is better than most magnetic carbon matrix composites. Our current approach opens up an effective way to develop low-cost, high-performance EMW absorbers.

scholarly journals High-efficiency and ultra-thin electromagnetic wave absorption xAl2O3-(1-x)Sr0.85Gd0.15TiO3 ceramics in X-band

2020 ◽  
Author(s):  
Hui Xie ◽  
Chaoqun Yang ◽  
Yingying Zhou ◽  
Zhaowen Ren ◽  
Ping Liu
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
High Efficiency ◽  
Impedance Matching ◽  
Frequency Dispersion ◽  
Interfacial Polarization ◽  
Peak Frequency ◽  
Microwave Absorbing Materials ◽  
Absorption Performance ◽  
Microwave Absorption Performance

Abstract xAl2O3-(1-x)Sr0.85Gd0.15TiO3(x=0.2, 0.3, 0.4, 0.5) ceramics were fabricated by hot-press sintering. Their morphology, phase composition, conductivity, dielectric properties as well as microwave absorption performance were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), multifunction digital four-probe meter and vector network analysis, respectively. The microwave absorption of as-prepared xAl2O3-(1-x)Sr0.85Gd0.15TiO3 ceramics demonstrates excellent microwave absorbability. It is unexpectedly found that with a thickness of only 0.346 mm, xAl2O3-(1-x)Sr0.85Gd0.15TiO3 (x=0.2) ceramic exhibits an absorption bandwidth of 3.7 GHz (8.7-12.4 GHz), being consequential to reflection loss less than -10 dB (over 90% of microwave absorption). It is as well discovered that the minimum reflection loss and absorption peak frequency of xAl2O3-(1-x)Sr0.85Gd0.15TiO3 (x=0.3) with a thickness of 0.436 mm were -45.43 dB and 11.3 GHz, respectively. The prominent microwave absorption performance of the ceramic with such a thin thickness can be attributed to strong interfacial polarization, dielectric frequency dispersion, and good electromagnetic impedance matching. It indicates that the xAl2O3-(1-x)Sr0.85Gd0.15TiO3 ceramics with appropriate Al2O3 mass fraction and thickness showing good potential for effective microwave absorbing materials.

scholarly journals An Easy Method of Synthesis CoxOy@C Composite with Enhanced Microwave Absorption Performance

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 902
Author(s):  
Wenli Bao ◽  
Cong Chen ◽  
Zhenjun Si
Keyword(s):  
Microwave Absorption ◽  
Impedance Matching ◽  
Interfacial Polarization ◽  
Magnetic Composite ◽  
Easy Method ◽  
Electromagnetic Absorption ◽  
Absorption Performance ◽  
Matched Impedance ◽  
Microwave Absorption Performance ◽  
Minimum Reflection Loss

Design of interface-controllable magnetic composite towards the wideband microwave absorber is greatly significance, however, it still remains challenging. Herein, we designed a spherical-like hybrids, using the Co3O4 and amorphous carbon as the core and shell, respectively. Then, the existed Co3O4 core could be totally reduced by the carbon shell, thus in CoxOy core (composed by Co and Co3O4). Of particular note, the ratios of Co and Co3O4 can be linearly tuned, suggesting the controlled interfaces, which greatly influences the interface loss behavior and electromagnetic absorption performance. The results revealed that the minimum reflection loss value (RLmin) of −39.4 dB could be achieved for the optimal CoxOy@C sample under a thin thickness of 1.4 mm. More importantly, the frequency region with RL < −10 dB was estimated to be 4.3 GHz, ranging from 13.7 to 18.0 GHz. The superior wideband microwave absorption performance was primarily attributed to the multiple interfacial polarization and matched impedance matching ability.

Efficient microwave traps with markedly enhanced interfacial polarization and impedance matching enabled by dual-shelled, dual-cavity magnetic@dielectric hollow nanospheres

2020 ◽  
Vol 8 (46) ◽  
pp. 16489-16497
Author(s):  
Jiasong Hua ◽  
Wenjun Ma ◽  
Xiaoyun Liu ◽  
Qixin Zhuang ◽  
Zeyang Wu ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
Impedance Matching ◽  
Interfacial Polarization ◽  
Hollow Nanospheres ◽  
Absorption Performance ◽  
Microwave Absorption Performance ◽  
Magnetic Dielectric ◽  
Minimum Reflection Loss

Dual-shelled, dual-cavity Fe3O4@TiO2 hollow nanospheres exhibit an outstanding microwave absorption performance with a minimum reflection loss of −60.17 dB.

scholarly journals Effect of Reaction Time on Microwave Absorption Properties of Fe3O4 Hollow Spheres Synthesized via Ostwald Ripening

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2921 ◽  
Author(s):  
Wei Huang ◽  
Yujiang Wang ◽  
Shicheng Wei ◽  
Bo Wang ◽  
Yi Liang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Microwave Absorption ◽  
Ostwald Ripening ◽  
Impedance Matching ◽  
Hollow Spheres ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Magnetic Structures ◽  
Absorption Performance ◽  
Microwave Absorption Performance

Hollow magnetic structures have great potential to be used in the microwave absorbing field. Herein, Fe3O4 hollow spheres with different levels of hollowness were synthesized by the hydrothermal method under Ostwald ripening effect. In addition to their microstructures, the microwave absorption properties of such spheres were investigated. The results show that the grain size and hollowness of Fe3O4 hollow spheres both increase as the reaction time increases. With increasing hollowness, the attenuation ability of electromagnetic wave of Fe3O4 spheres increases first and then decreases, finally increases sharply after the spheres break down. Samples with strong attenuation ability can achieve good impedance matching, which it does preferentially as the absorber thickness increases. Fe3O4 hollow spheres show the best microwave absorption performance when the reaction time is 24 h. The minimum reflection loss (RL (min)) can reach −40 dB, while the thickness is only 3.2 mm.

Synthesis and Excellent Microwave Absorption Properties of ZnO/Fe3O4/MWCNTs Composites

NANO ◽  
2016 ◽  
Vol 11 (12) ◽  
pp. 1650139 ◽  
Author(s):  
Lei Wang ◽  
Honglong Xing ◽  
Zhenfeng Liu ◽  
Ziyao Shen ◽  
Xiang Sun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Microwave Absorption ◽  
Photoelectron Spectroscopy ◽  
Wave Attenuation ◽  
Impedance Matching ◽  
Interfacial Polarization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zno Nanocrystals ◽  
Transmission Electron

ZnO nanocrystals were introduced into Fe3O4/MWCNTs composites to improve the impedance matching and electromagnetic (EM) wave attenuation of the system. The as-synthesized ZnO/Fe3O4/MWCNTs composites were characterized by X-ray diffraction, vibrating sample magnetometer, field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy. SEM and TEM images showed that Fe3O4 microspheres 100–200[Formula: see text]nm in size connected MWCNTs. Analysis of EM parameters revealed that the impedance matching of the ZnO/Fe3O4/MWCNTs composites was considerably improved after ZnO nanocrystals were introduced. The ZnO/Fe3O4/MWCNTs composites exhibited a highly efficient microwave absorption (MA) capacity within the tested frequency range of 2–18[Formula: see text]GHz. The optimal reflection loss of EM waves was [Formula: see text][Formula: see text]dB at 6.08[Formula: see text]GHz with an absorber thickness of 3.5[Formula: see text]mm. The excellent MA properties of the composites could be attributed to the improved impedance matching, interfacial polarization, and combined effects of dielectric and magnetic losses.

Constructing Ni12P5/Ni2P Heterostructures to Boost Interfacial Polarization for Enhanced Microwave Absorption Performance

2020 ◽  
Vol 12 (46) ◽  
pp. 52208-52220 ◽  
Author(s):  
Lei-Lei Liang ◽  
Ge Song ◽  
Zhuo Liu ◽  
Jing-Peng Chen ◽  
Li-Jing Xie ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Interfacial Polarization ◽  
Absorption Performance ◽  
Microwave Absorption Performance

scholarly journals A New Broadband and Strong Absorption Performance FeCO3/RGO Microwave Absorption Nanocomposites

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2206 ◽  
Author(s):  
Wei Huang ◽  
Shicheng Wei ◽  
Yujiang Wang ◽  
Bo Wang ◽  
Yi Liang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Microwave Absorption ◽  
Solvothermal Method ◽  
Impedance Matching ◽  
Effective Bandwidth ◽  
Broad Absorption ◽  
Promising Candidate ◽  
Reduced Graphene ◽  
Absorption Performance

A novel composite of FeCO3 nanoparticles, which are wrapped with reduced graphene oxide (RGO), is fabricated using a facile one-spot solvothermal method. The composite consists of a substrate of RGO and FeCO3 nanoparticles that are embedded in the RGO layers. The experimental results for the FeCO3/RGO composite reveal a minimum refection loss (−44.5 dB) at 11.9 GHz when the thickness reaches 2.4 mm. The effective bandwidth is 7.9 GHz between 10.1 and 18 GHz when the refection loss was below −10 dB. Compared to GO and RGO, this type of composite shows better microwave absorption thanks to improved impedance matching. Overall, this thin and lightweight FeCO3/RGO composite is a promising candidate for absorbers that require both strong and broad absorption.

scholarly journals Solvent-Free Synthesis of Ultrafine Tungsten Carbide Nanoparticles-Decorated Carbon Nanosheets for Microwave Absorption

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yunlong Lian ◽  
Binhua Han ◽  
Dawei Liu ◽  
Yahui Wang ◽  
Honghong Zhao ◽  
...  
Keyword(s):  
Tungsten Carbide ◽  
Microwave Absorption ◽  
Impedance Matching ◽  
Weight Ratio ◽  
Solvent Free ◽  
Carbon Composites ◽  
Carbon Nanosheets ◽  
Solid Mixture ◽  
Absorption Performance ◽  
Microwave Absorption Performance

AbstractCarbides/carbon composites are emerging as a new kind of binary dielectric systems with good microwave absorption performance. Herein, we obtain a series of tungsten carbide/carbon composites through a simple solvent-free strategy, where the solid mixture of dicyandiamide (DCA) and ammonium metatungstate (AM) is employed as the precursor. Ultrafine cubic WC1−x nanoparticles (3–4 nm) are in situ generated and uniformly dispersed on carbon nanosheets. This configuration overcomes some disadvantages of conventional carbides/carbon composites and is greatly helpful for electromagnetic dissipation. It is found that the weight ratio of DCA to AM can regulate chemical composition of these composites, while less impact on the average size of WC1−x nanoparticles. With the increase in carbon nanosheets, the relative complex permittivity and dielectric loss ability are constantly enhanced through conductive loss and polarization relaxation. The different dielectric properties endow these composites with distinguishable attenuation ability and impedance matching. When DCA/AM weight ratio is 6.0, the optimized composite can produce good microwave absorption performance, whose strongest reflection loss intensity reaches up to − 55.6 dB at 17.5 GHz and qualified absorption bandwidth covers 3.6–18.0 GHz by manipulating the thickness from 1.0 to 5.0 mm. Such a performance is superior to many conventional carbides/carbon composites.

Sign in / Sign up

Export Citation Format

Share Document