scholarly journals Excellent Microwave Absorption Properties Derived from the Synthesis of Hollow Fe3o4@Reduced Graphite Oxide (RGO) Nanocomposites

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 141 ◽  
Author(s):  
Guangzhen Cui ◽  
Yanli Lu ◽  
Wei Zhou ◽  
Xuliang Lv ◽  
Jiangnan Hu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Microwave Absorption ◽  
Reflection Loss ◽  
Graphite Oxide ◽  
Photoelectron Spectroscopy ◽  
Impedance Matching ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Reduced Graphite Oxide

Magnetic nanoparticles, such as Fe3O4 and Co3O4, play a vital role in the research on advanced microwave absorbing materials, even if problems such as high density and narrow band impedance matching are still unsolved. Herein, the study of lightweight hollow Fe3O4@reduced graphite oxide (RGO) nanocomposites synthesized via the solvothermal method is presented. The microstructure and crystal morphology of the materials were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. Single crystalline hollow Fe3O4 spheres were grown onto RGO flakes, leading to the formation of heterojunction, which further influenced the microwave absorption properties. The latter were evaluated by standard microwave characterization in the frequency range of 2–18 GHz. It was found that, for a specific [email protected] g RGO composite, the minimum reflection loss can reach −41.89 dB at 6.7 GHz, while the reflection loss was less than −10 dB from 3.4 GHz to 13.6 GHz for a nanocomposite sample thickness in the range of 1–4 mm. The combination of these two materials thus proved to give remarkable microwave absorption properties, owing to enhanced magnetic losses and favorable impedance matching conditions.

Prepared and Microwave-Absorption Properties Investigation of χ-C-Fe-Si/SiC Coated Fe Nanocapsules

2009 ◽  
Vol 79-82 ◽  
pp. 743-746 ◽  
Author(s):  
Gui Mei Shi ◽  
Jin Hu Zhang ◽  
Shu Lian ◽  
Ge Song ◽  
Jin Bing Zhang
Keyword(s):  
Electron Microscopy ◽  
Reflection Loss ◽  
Photoelectron Spectroscopy ◽  
Network Analyzer ◽  
Absorber Thickness ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Transmission Electron

-C-Fe-Si/SiC coated Fe nanocapsules were prepared by arc evaporating the mixture of Fe and SiC powders in He and H2 atmosphere, and their microstructure, surface compositions and electromagnetic(EM) properties(2–18GHz) were investigated by means of high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and network analyzer, respectively. The reflection loss R of less than –20 dB was obtained in the frequency range of 3.13–13.6 GHz with an absorber thickness of 2.0–5.5 mm. An optimal reflection loss of–37.2 dB was reached at 5.6GHz with an absorber thickness of 4.5mm. The microwave absorptive mechanisms of -C-Fe-Si/SiC coated Fe nanocapsules absorbent were discussed.

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.

Coprecipitation Synthesis of Fe-doped ZnO Powders with Enhanced Microwave Absorption Properties

NANO ◽  
2016 ◽  
Vol 11 (12) ◽  
pp. 1650136 ◽  
Author(s):  
Ruiwen Shu ◽  
Xin Wang ◽  
Yingying Yang ◽  
Xiayu Tang ◽  
Xian Zhou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Crystal Lattice ◽  
Microwave Absorption ◽  
Reflection Loss ◽  
Ferromagnetic Behavior ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Zno Powders ◽  
Doped Zno

In this work, the Fe-doped ZnO powders have been synthesized by a facile chemical coprecipitation method. The structure, morphology and magnetic properties of the as-prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The results showed that the Fe ions were well incorporated into the crystal lattice of ZnO and had a valence state of [Formula: see text]. The magnetization curves indicated the Fe-doped ZnO presented the ferromagnetic behavior at room temperature. Moreover, the electromagnetic (EM) parameters and microwave absorption properties of Fe-doped ZnO/paraffin wax in the frequency range of 2–18[Formula: see text]GHz were explored. The minimum reflection loss reached [Formula: see text] dB at 6.6 GHz, and the reflection loss less than [Formula: see text] dB was 4.0 GHz (from 11.0[Formula: see text]GHz to 15.0[Formula: see text]GHz) with a thickness of only 2.5 mm. Significantly, the enhanced microwave absorption of the as-prepared powders could be achieved by doping with Fe[Formula: see text] ions or varying the thickness of the absorbers. The mechanism of microwave absorption were attributed to the good impedance matching, the dielectric loss resulted from the crystal lattice defects and the magnetic loss originated from the natural resonance. It is believed that the Fe-doped ZnO powders could be used as potential microwave absorbers.

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.

Synthesis of holey reduced graphene oxide covered in the FeCo@SiO2 and their enhanced electromagnetic absorption properties

2018 ◽  
Vol 53 (14) ◽  
pp. 1973-1983 ◽  
Author(s):  
Suping Li ◽  
Ying Huang ◽  
Na Zhang ◽  
Meng Zong
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Reflection Loss ◽  
Photoelectron Spectroscopy ◽  
Absorption Properties ◽  
Absorption Bandwidth ◽  
X Ray ◽  
Oxide Composite ◽  
Reduced Graphene

The FeCo@SiO2/holey reduced graphene oxide composite was successfully prepared by combining liquid-phase reduction reaction in argon atmosphere with high-temperature calcination. The FeCo@SiO2/holey reduced graphene oxide composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, vibrating sample magnetometer, Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy and scanning electron microscopy analysis and exhibit excellent electromagnetic wave absorption properties. The maximum reflection loss of FeCo@SiO2/holey reduced graphene oxide composite reaches –46.28 dB at 16.16 GHz with the thickness of 1.5 mm and the absorption bandwidth with the reflection loss below –10 dB was up to 3.92 GHz (from 14.08 GHz to 18 GHz) with the thickness of 1.5 mm. The absorption bandwidth with RL below –10 dB is up to 12.64 GHz. It is believed that the FeCo@SiO2/holey reduced graphene oxide composite can serve as an excellent microwave absorber.

scholarly journals Synthesis and Microwave Absorption Properties of Sulfur-Free Expanded Graphite/Fe3O4 Composites

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3044
Author(s):  
Jian Sun ◽  
Lijie Li ◽  
Rui Yu ◽  
Xianlong Ma ◽  
Shaohua Jin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Microwave Absorption ◽  
Large Scale ◽  
Expanded Graphite ◽  
Raw Material ◽  
Precipitation Method ◽  
Absorption Properties ◽  
One Pot ◽  
Microwave Absorption Properties ◽  
X Ray

In this study, sulfur-free expanded graphite (EG) was obtained by using flake graphite as the raw material, and EG/Fe3O4 composites with excellent microwave absorption properties were prepared by a facile one-pot co-precipitation method. The structure and properties of as-prepared EG/Fe3O4 were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Raman, X-ray photoelectron spectrometry (XPS), thermogravimetric (TG), and vibrating sample magnetometry (VSM) characterizations. The Fe3O4 intercalated between the layers of expanded graphite forms a sandwich-like structure which is superparamagnetic and porous. When applied as a microwave absorber, the reflection loss (RL) of EG/Fe3O4 reaches −40.39 dB with a thickness of 3.0 mm (10 wt% loading), and the effective absorption bandwidth (EAB < −10 dB) with RL exceeding −10 dB is 4.76–17.66 GHz with the absorber thickness of 1.5–4.0 mm. Considering its non-toxicity, easy operation, low cost, suitability for large-scale industrial production, and excellent microwave absorbing performance, EG/Fe3O4 is expected to be a promising candidate for industrialized electromagnetic absorbing materials.

Prepared and Microwave-Absorption Properties of SiC Coated Ni Nanocapsules

2011 ◽  
Vol 217-218 ◽  
pp. 152-157 ◽  
Author(s):  
Gui Mei Shi ◽  
Jin Bing Zhang ◽  
Shu Lian ◽  
Long Shan Chen
Keyword(s):  
Reflection Loss ◽  
Photoelectron Spectroscopy ◽  
Shell Structure ◽  
Core Shell ◽  
Absorber Thickness ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Core Shell Structure

SiC coated Ni nanocapsules were prepared by arc evaporating the mixture of Ni and SiC powders in Ar and H2 atmosphere. HRTEM shows the as-prepared nanoparticles form in a core¬¬¬-shell structure, with the size of nanoparticles in range of 20-50nm and the thickness of the shell 2-6nm. X-Ray and X-ray photoelectron spectroscopy show core consist of Ni, while the shell consists of SiC. The core-shell structure can prevent Ni nanoparticles from oxidation and agglomeration. The electromagnetic characters were measured by Agilent 8722ES microwave network analyzer in the band of 2-18GHz. The reflection loss R(dB) of less than –20 dB was obtained in the frequency range of 3.8-11.1GHz with absorber thickness of 2.5–5mm, An optimal reflection loss of –33.4dB was reached at 7.4GHz with an absorber thickness of 3.5mm.In addition, the optimal RL obviously shifts to the lower-frequency range with increasing thickness of the layer.

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, 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.

The synergistic effects of carbon coating and micropore structure on the microwave absorption properties of Co/CoO nanoparticles

2016 ◽  
Vol 18 (44) ◽  
pp. 30507-30514 ◽  
Author(s):  
Xiubo Xie ◽  
Yu Pang ◽  
Hiroaki Kikuchi ◽  
Tong Liu
Keyword(s):  
Microwave Absorption ◽  
Vapor Deposition ◽  
Carbon Coating ◽  
Synergistic Effects ◽  
Impedance Matching ◽  
Chemical Vapor ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Micropore Structure ◽  
Coo Nanoparticles

Microporous Co/CoO/C nanoparticles prepared by combining chemical dealloying and chemical vapor deposition methods exhibited high microwave absorption properties due to the synergistic effects of the carbon coating and the micropore structure on the impedance matching of the absorber.

Sign in / Sign up

Export Citation Format

Share Document