scholarly journals Enhanced Microwave Absorption and Electromagnetic Properties of Si-Modified rGO@Fe3O4/PVDF-co-HFP Composites

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 933 ◽  
Author(s):  
Yuexuan Li ◽  
Yugang Duan ◽  
Chengmeng Wang
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
High Efficiency ◽  
Vinylidene Fluoride ◽  
Synergistic Effects ◽  
Electromagnetic Properties ◽  
Absorption Mechanism ◽  
Simple Method ◽  
Absorption Frequency ◽  
Enhanced Absorption

Graphene has been regarded as one of the most promising two-dimensional nanomaterials. Even so, graphene was still faced with several key issues such as impedance mismatching and narrow bandwidth, which have hindered the practical applications of graphene-based nanocomposites in the field of microwave absorption materials. Herein, a series of Si-modified rGO@Fe3O4 composites were investigated and fabricated by a simple method. On one hand, the degree of defects in graphene carbon could be tuned by different silane coupling reagents, which were beneficial to enhancing the dielectric loss. On the other hand, the spherical Fe3O4 nanoparticles provided the magnetic loss resonance, which contributed to controlling the impedance matching. Subsequently, the electromagnetic absorption (EMA) properties of Si-modified rGO@Fe3O4 composites with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) were investigated in this work. As a result, the Si(2)-rGO@Fe3O4/PVDF-co-HFP composite exhibited the excellent EMA performance in the range of 2–18 GHz. The maximum reflection loss (RLmax) reached −32.1 dB at 3.68 GHz at the thickness of 7 mm and the effective absorption frequency bandwidth for reflection loss (RL) below −10 dB was 4.8 GHz at the thickness of 2 mm. Furthermore, the enhanced absorption mechanism revealed that the high-efficiency absorption performance of Si(2)-rGO@Fe3O4/PVDF-co-HFP composite was attributed to the interference absorption (quarter-wave matching model) and the synergistic effects between Si(2)-rGO@Fe3O4 and PVDF-co-HFP. This work provides a potential strategy for the fabrication of the high-performance EMA materials.

scholarly journals Electromagnetic Properties Performance of MWCNTs/Polyester Composites in X-band

2018 ◽  
Vol 150 ◽  
pp. 06014 ◽  
Author(s):  
Y. S. Lee ◽  
F. H. Wee ◽  
K. Y. You ◽  
C. Y. Lee ◽  
Y. Y. Lee ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
Weight Ratio ◽  
Electromagnetic Properties ◽  
Band Frequency ◽  
Microwave Absorbing Materials ◽  
X Band ◽  
Line Theory ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this paper presents nano-composites based on polyester (PE) matrix with multi-walled carbon nanotubes (MWCNTs) as fillers have been developed for microwave absorbing materials. The MWCNTs/PE composite samples were fabricated with different weight ratio of MWCNTs (3 wt%, 5 wt%, and 10 wt%). The electromagnetic properties of different MWCNTs/PE composite have been determined by using rectangular waveguide technique and Agilent material measurement software. Moreover, the reflection loss (microwave absorption) of MWCNTs/PE composite have been calculated based on the basis of transmission line theory. The performance of electromagnetic properties and microwave absorption of MWCNTs/PE composite were analyzed in X-band frequency. The dielectric loss properties of the composite are increse with increasing in MWCNTs weight ratio. The microwave absorption results show that such 3 wt% MWCNTs/PE composites sample with 4 mm thickness has achieved less than -10 dB values (< 90 % microwave absorption) of reflection loss.

FACILE SYNTHESIS AND MICROWAVE ABSORPTION PROPERTIES OF α-MnO2 NANORODS

2012 ◽  
Vol 05 (04) ◽  
pp. 1250043 ◽  
Author(s):  
HONGTAO GUAN ◽  
GANG CHEN ◽  
JING ZHU ◽  
YUDE WANG
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
Chemical Precipitation ◽  
Electromagnetic Properties ◽  
Precipitation Method ◽  
Electronic Microscopy ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
5 Ghz ◽  
Peak Value

A low-temperature water-bathing chemical precipitation method was developed to synthesize α- MnO2 nanorods. The morphological and crystalline structures were investigated by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and X-ray diffraction (XRD) spectra. The electromagnetic properties and microwave absorption properties were examined in the frequency range 2–18 GHz. The results show that the as-synthesized product is α- MnO2 nanorod with diameters of 30 nm and lengths up to 1–2 μm. The dielectric permittivity has a trend of decreasing its real and increasing its imaginary parts with the frequency. The magnetic permeability is about 1.0–1.2 and 0–0.1 for its real and imaginary parts at the whole frequency. With the increase of sample thickness, the reflection loss peak value shifts to lower frequency band. With a thickness of 3 mm, an absorption peak value of -25 dB was achieved. And its effective absorption bandwidth in which the reflection loss is lower than -10 dB is as high as 5 GHz.

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.

MXene–modulated 3D crosslinking network of hierarchical flower–like MOF derivatives towards ultra–efficient microwave absorption property

2021 ◽  
Author(s):  
Hui-Ya Wang ◽  
Xiaobo Sun ◽  
Guang-Sheng Wang
Keyword(s):  
Microwave Absorption ◽  
High Efficiency ◽  
Microwave Absorption Property ◽  
Electromagnetic Properties ◽  
Absorption Property ◽  
Portable Electronics ◽  
Increasing Demand

Lightweight and high–efficiency microwave absorption materials with tunable electromagnetic properties still remain challenging to meet the increasing demand for portable electronics. In this work, MOF derivatives/MXene crosslinking networks were successfully...

scholarly journals Investigation of the Broadband Microwave Absorption of Citric Acid Coated Fe3O4/PVDF Composite Using Finite Element Method

2019 ◽  
Vol 9 (18) ◽  
pp. 3877 ◽  
Author(s):  
Lawal Lanre Adebayo ◽  
Hassan Soleimani ◽  
Noorhana Yahya ◽  
Zulkifly Abbas ◽  
Ayinla Tobi Ridwan ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Citric Acid ◽  
Microwave Absorption ◽  
Fe3o4 Nanoparticles ◽  
Electromagnetic Properties ◽  
Frequency Range ◽  
Band Frequency ◽  
Enhanced Absorption ◽  
Element Method

Magnetite (Fe3O4) have been thoroughly investigated as microwave absorbing material due to its excellent electromagnetic properties (permittivity and permeability) and favorable saturation magnetization. However, large density and impedance mismatch are some of the limiting factors that hinder its microwave absorption performance (MAP). Herein, Fe3O4 nanoparticles prepared by facile co-precipitation method have been coated with citric acid and embedded in a polyvinylidene fluoride (PVDF) matrix. The coated Fe3O4 nanoparticles were characterized by X-ray diffraction spectrometer (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). COMSOL Multiphysics based on the finite element method was used to simulate the rectangular waveguide at X-band and Ku-band frequency range in three-dimensional geometry. The citric acid coated Fe3O4/PVDF composite with 40 wt.% filler loading displayed good microwave absorption ability over the studied frequency range (8.2–18 GHz). A minimum reflection loss of −47.3 dB occurs at 17.9 GHz with 2.5 mm absorber thickness. The composite of citric acid coated Fe3O4 and PVDF was thus verified as a potential absorptive material with improved MAP. These enhanced absorption coefficients can be ascribed to favorable impedance match and moderate attenuation.

Electromagnetic Properties of Nanometer SiC/CNTs Composite

2009 ◽  
Vol 79-82 ◽  
pp. 349-352 ◽  
Author(s):  
Jian Xun Yao ◽  
Liu Ying Wang ◽  
Gu Liu ◽  
Shao Chun Hua
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
Complex Permittivity ◽  
Mass Fraction ◽  
Low Frequency ◽  
Electromagnetic Properties ◽  
Transmission Line Theory ◽  
Microwave Absorption Properties ◽  
Line Theory ◽  
Maximum Reflection Loss

Both the complex permittivity and permeability of nanometer SiC and nanometer SiC/CNTs composite were investigated by Hewlett-Packard 8510B Network Analyzer. The results show that the complex permittivity of nanometer SiC/CNTs composite is much higher than that of nanometer SiC. Reflection curves of nanometer SiC and nanometer SiC/CNTs composite calculated with electromagnetic wave transmission-line theory show that the addition of CNTs at 6 wt%, 12 wt% and 18 wt% in nanometer SiC absorber can improve its microwave absorption properties strongly. There is a relationship between the mass fraction of CNTs and microwave absorption ability. With increase of the mass fraction of CNTs, its microwave absorption ability firstly increased then decreased. From the simulation, it was found that nanometer SiC with 12 wt% CNTs gave the optimum microwave absorption. The corresponding frequency of maximum reflection loss value of nanometer SiC/CNTs composite gradually moves to the low frequency range with increase of thickness. The maximum reflection loss value of nanometer SiC/CNTs composite (CNTs content is 12 wt%) was -25.74dB at the corresponding frequency of 11.60 GHz with a bandwidth under -5 dB (68% absorption) is 7.16 GHz when the thickness is 2.0 mm.

Heterogeneous iron–nickel compound/RGO composites with tunable microwave absorption frequency and ultralow filler loading

2020 ◽  
Vol 22 (16) ◽  
pp. 8639-8646 ◽  
Author(s):  
Miaomiao Zhang ◽  
Zhiyang Jiang ◽  
Haoxu Si ◽  
Xuefeng Zhang ◽  
Caixia Liu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Microwave Absorption ◽  
High Efficiency ◽  
Filler Loading ◽  
Nickel Compound ◽  
Absorption Frequency ◽  
Reduced Graphene ◽  
Iron Nickel ◽  
Oxide Composites ◽  
Tunable Absorption

Heterogeneous iron–nickel compound/reduced graphene oxide composites were fabricated to obtain lightweight and high-efficiency microwave absorption materials with tunable absorption frequency.

scholarly journals Facile Synthesis of GNPs@NixSy@MoS2 Composites with Hierarchical Structures for Microwave Absorption

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1403 ◽  
Author(s):  
Wenfeng Zhu ◽  
Li Zhang ◽  
Weidong Zhang ◽  
Fan Zhang ◽  
Zhao Li ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Microwave Absorption ◽  
Reflection Loss ◽  
Skin Effect ◽  
Hydrothermal Reaction ◽  
Synergistic Effects ◽  
Hierarchical Structures ◽  
Dielectric Losses ◽  
Facile Synthesis ◽  
Molar Ratios

Graphene-based powder absorbers have been used to attain excellent microwave absorption. However, it is not clear if inferior microwave absorption by pure graphene materials can be attributed to impedance mismatching or inadequate attenuation capability. In this comparative study, we focus on these aspects. Graphene nanoplatelets (GNPs) multi-component composites (GNPs@NixSy@MoS2) were prepared by hydrothermal reaction with different S and Mo molar ratios. The morphologies, phase crystals, elemental composition, and magnetic properties of the composites were also analyzed. In addition, microwave absorption of the as-prepared samples was investigated and it revealed that the impedance mismatching could be responsible for inferior microwave absorption; higher conductivity can lead to skin effect that inhibits the further incidence of microwaves into the absorbers. Furthermore, the optimum reflection loss (RL) of GNPs@NixSy@MoS2-2 can reach −43.3 dB at a thickness of 2.2 mm and the corresponding bandwidth with effective attenuation (RL < −10 dB) of up to 3.6 GHz (from 7.0 to 10.6 GHz). Compared with the GNPs, the enhanced microwave absorption can be assigned to the synergistic effects of conductive and dielectric losses.

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