Preparation and Investigation of Co-Dispersed MWCNT Buckypaper for the Microwave Absorption

2013 ◽  
Vol 479-480 ◽  
pp. 20-24 ◽  
Author(s):  
Lakshmanan Saravanan ◽  
Jih Hsin Liu ◽  
Hsin Yuan Miao ◽  
Li Chih Wang
Keyword(s):  
Microwave Absorption ◽  
Cobalt Nanoparticles ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Filtration Method ◽  
X Ray ◽  
Multi Walled Carbon Nanotube ◽  
Co Nanoparticles

The paper deals with the preparation of cobalt nanoparticles dispersed multi walled carbon nanotube buckypaper by the dispersion and filtration method to study the electromagnetic (microwave) absorption properties. From the X-ray diffraction the crystallite size of the cobalt nanoparticles of 33.04 nm was calculated. FESEM image clearly indicates the presence of cobalt nanoparticles in the buckypaper. Microwave-absorbing properties were investigated in terms of measuring the transmission coefficient (S21) with MWCNT-buckypaper as the absorber using microstrip line in a frequency range of 2–20 GHz. Compared to the pure buckypaper the absorption peak of the Co-CNT composites move to the lower frequency by dispersing the Co nanoparticles into the MWCNT-BP.

MICROWAVE ABSORPTION BEHAVIOR OF MESOPOROUS TRANSITION METAL OXIDE TEMPLATED FROM SBA-15 AND KIT-6

2014 ◽  
Vol 28 (10) ◽  
pp. 1450037 ◽  
Author(s):  
HONGJING WU ◽  
LIUDING WANG ◽  
YIMING WANG
Keyword(s):  
Electron Microscope ◽  
Microwave Absorption ◽  
Absorption Characteristic ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Hard Template ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Transmission Electron

In this paper, we have synthesized meso-oxides (i.e., Co 3 O 4 and NiO ) by using mesoporous silica as hard template. The microstructures and chemical compositions of the corresponding meso-oxides were characterized by the Transmission electron microscope-selected area electron diffusion (TEM-SAED), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), respectively. And, their electromagnetic and microwave absorption properties were investigated in the frequency range of 2–18 GHz. The results indicate that meso-oxide templated from KIT-6 (i.e., meso-K– Co / Ni ) exhibit a dual absorption characteristic compared with those using SBA-15 as hard template. This phenomenon suggests that meso-oxides templated from SBA-15 and KIT-6 can exhibit different microwave absorption behaviors due to their respective microstructures.

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.

Synthesis, Characterization, and Microwave Absorption Properties of SrFe12O19 Ferrites and FeNi3 Nanoplatelets Composites

2010 ◽  
Vol 148-149 ◽  
pp. 893-896 ◽  
Author(s):  
Ze Yang Zhang ◽  
Xiang Xuan Liu ◽  
You Peng Wu
Keyword(s):  
Electron Microscopy ◽  
Microwave Absorption ◽  
Composite Coatings ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Filling Fraction ◽  
Microwave Absorption Properties ◽  
Phase Reduction ◽  
Transmission Electron

M-typical SrFe12O19 ferrites and FeNi3 nanoplatelets were successfully prepared by the sol-gel method and solution phase reduction method, respectively. The crystalline and morphology of particles were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The composite coatings with SrFe12O19 ferrites and FeNi3 nanoplatelets in polyvinylchloride matrix were prepared. The microwave absorption properties of these coatings were investigated in 2-18GHz frequency range. The results showed that the M-typical SrFe12O19 ferrites and FeNi3 nanoplatelets were obtained and they presented irregular sheet shapes. With the increase of the coating thickness, the absorbing peak value moves to the lower frequency. The absorbing peak values of the wave increase along with the increasing of the content of FeNi3 nanoplatelets filling fraction. When 40% SrFe12O19 ferrites is doped with 20% mass fraction FeNi3 nanoplatelets to prepare composite with 1.5mm thickness, the maximum reflection loss is -24.8 dB at 7.9GHz and the -10 dB bandwidth reaches 3.2GHz.

Magnetization and Microwave Absorption Properties of La0.67 Sr0.33 MnO3 with Different Particle Size

2011 ◽  
Vol 374-377 ◽  
pp. 1541-1544 ◽  
Author(s):  
Yu Lan Cheng ◽  
Ping Xia ◽  
Ke Xiang Wei ◽  
Quan Bai
Keyword(s):  
Particle Size ◽  
Sinter Temperature ◽  
Microwave Absorption ◽  
Reflection Loss ◽  
Sol Gel ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Measured Frequency Range ◽  
Maximum Reflection Loss

La 0.67 Sr 0.33 MnO 3 particles with different particle size have been prepared by sol-gel method. The structure, magnetization and microwave absorption properties have been investigated. The results show that the particle size can be controlled by sinter temperature. The peaks of the maximum reflection loss (RL) move to higher frequency regions with increasing particle size. The value of the maximum RL is -32 dB at 10.2GHz with a particle size of 58.5nm. The bandwidth with a RL exceeding -8dB reached 1.6GHz in the whole measured frequency range, suggesting that La 0.67 Sr 0.33 MnO 3 particles are promising for application as a wideband and strong absorption building microwave absorber.

Prepared and Microwave-Absorption Properties of BN Coated Ni Nanocapsules

2010 ◽  
Vol 663-665 ◽  
pp. 1252-1255 ◽  
Author(s):  
Gui Mei Shi ◽  
Shu Lian ◽  
Ge Song ◽  
Jin Bing Zhang
Keyword(s):  
Reflection Loss ◽  
Electromagnetic Properties ◽  
Mechanochemical Reaction ◽  
Network Analyzer ◽  
Absorber Thickness ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Transmission Electron

BN coated Ni nanocapsules were prepared by arc evaporating Ni-B amorphous alloy powders synthesized by a mechanochemical reaction, and their microstructure, surface component as well as electromagnetic properties (2-18 GHz) were investigated by means of high-resolution transmission electron microscopy, X-ray diffraction , photoluminescence spectra (PL) and a network analyzer, respectively. The reflection loss R (dB) of the nanocapsules less than -20 dB was obtained in the frequency range of 4.3-18 GHz for an absorber thickness of 1.4-6 mm. An optimal reflection loss of -32.0 dB was reached at 13 GHz with an absorber thickness of 2 mm. The microwave absorptive mechanisms of BN-coated Ni nanocapsule absorbent were discussed.

Magnetic and Microwave Absorption Properties of Magnetite-Durian Shell Nanocomposite Sheet in Gigahertz Range

2018 ◽  
Vol 775 ◽  
pp. 217-223
Author(s):  
Afraha Baiti Arif ◽  
Rose Farahiyan Munawar ◽  
Qumrul Ahsan ◽  
Maisarah Abu
Keyword(s):  
Microwave Absorption ◽  
Electromagnetic Interference ◽  
Filler Content ◽  
Spherical Shape ◽  
Constant Thickness ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Weight Percentage ◽  
Durio Zibethinus

In this paper, a novel microwave absorber of thin, light weight, flexible, green and low cost magnetic nanocomposite sheet that can work in high frequency range is fabricated. The vast and increasing numbers in electronic and telecommunication devices has create electromagnetic interference (EMI) in which may lead to application disturbance. Therefore, electromagnetic (EM) wave absorber with the ability of high absorption rate is strongly demanded. Here, durian shell (Durio zibethinus Murray) embedded magnetite (Fe3O4) nanocomposite sheets were prepared via pulping and lumen loading technique. The nanocomposite sheets were fabricated by varying the weight percentage of the filler content (2-10 wt% of Fe3O4) at constant thickness and varying the thickness of the sheets (0.1-1.0 mm) at constant filler content. FESEM micrograph shows that the Fe3O4 nanoparticles are in cubical and spherical shape with the 20–50 nm of size range. The microwave absorption properties of the sheets were tested by a vector network analyze (VNA) in the frequency range of 4-18 GHz. The samples were also tested using vibrating sample magnetometer (VSM) in order to study the magnetic properties. The absorption or maximum reflection loss (RL) of the samples increases continually and the increase of both filler content and sample thickness has led to the shift of dip to lower frequency region.

Single-Layer and Double-Layer Microwave Absorbers Based on Graphene Nanosheets/Epoxy Resin Composite

NANO ◽  
2017 ◽  
Vol 12 (07) ◽  
pp. 1750089 ◽  
Author(s):  
Dandan Min ◽  
Wancheng Zhou ◽  
Yuchang Qing ◽  
Fa Luo ◽  
Dongmei Zhu
Keyword(s):  
Absorption Band ◽  
Epoxy Resin ◽  
Microwave Absorption ◽  
Double Layer ◽  
Graphene Nanosheets ◽  
Resin Composite ◽  
Single Layer ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties

Graphene nanosheets/epoxy resin (GN/EP) composites with enhanced microwave absorption properties were prepared. The influence of GNs content on the electromagnetic and microwave-absorbing properties of single-layer GN/EP composites was investigated in the frequency range of 2–18[Formula: see text]GHz. A novel double-layer microwave absorber by combining absorbers with different contents of graphene was designed to achieve absorbers with wide absorption band and optimal microwave absorption. The calculated microwave absorption properties indicated that broader absorption band was obtained by the double-layer GN/EP composites. Reflection loss (RL) values below [Formula: see text]5[Formula: see text]dB can be obtained in the frequency range of 4.4–18[Formula: see text]GHz by the double-layer GN/EP composites at thickness of 3.9[Formula: see text]mm.

A Comparable Study on the Microwave Absorption Properties of Al/Fe/Co Doped OMC/Paraffin Wax Composites

NANO ◽  
2016 ◽  
Vol 11 (02) ◽  
pp. 1650014 ◽  
Author(s):  
Yanyan Ren ◽  
Hongfeng Li ◽  
Guanglei Wu ◽  
Le Yang ◽  
Chenhui Zheng ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Impedance Matching ◽  
Paraffin Wax ◽  
Frequency Range ◽  
Great Role ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Broadband Absorption ◽  
Ordered Mesoporous ◽  
Co Doped

Al/Fe/Co doped ordered mesoporous carbon (OMC) composites have been synthesized by a facile method, and the influence of dopant on the electromagnetic (EM) and microwave absorption properties was investigated in the frequency range of 2–18[Formula: see text]GHz. Compared with Fe/Co–OMC composites, the Al–OMC nanocomposite played a great role in adjusting values and frequency dependence of complex permittivity, which gives rise to significant improved microwave absorption and reduced thickness of the corresponding paraffin wax composites. Reflection loss (RL) values less than [Formula: see text]5[Formula: see text]dB and [Formula: see text]10[Formula: see text]dB were obtained in the frequency range of 9.2–18[Formula: see text]GHz and 10.7–14.7[Formula: see text]GHz with a single thickness of 2.00[Formula: see text]mm, respectively. Such enhanced EM wave absorption property of the Al–OMC/paraffin wax composite was ascribed to its superior impedance matching characteristic. Thin thickness, broadband absorption microwave absorbers with Al doped OMC nanocomposites were obtained.

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