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.

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.

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 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.

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.

Synthesis and Microwave-Absorbing Properties of Al2O3 Coated Polyhedral Fe Nanocapsules Prepared by Arc-Discharge Method

2011 ◽  
Vol 299-300 ◽  
pp. 739-742 ◽  
Author(s):  
Gui Mei Shi ◽  
Jin Bing Zhang ◽  
Da Wei Yu ◽  
Long Shan Chen
Keyword(s):  
Photoelectron Spectroscopy ◽  
Arc Discharge ◽  
Electromagnetic Properties ◽  
Al Alloy ◽  
Network Analyzer ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Transmission Electron ◽  
Discharge Method

Al2O3coated polyhedral Fe nanocapsules were prepared by arc-discharging a Fe-Al(8at%Al) alloy. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy, and network analyzer were employed to investigate the microstructures, compositions and electromagnetic properties (2-18GHz). The reflection loss R(dB) of the nanocapsules reaches to -50.5dB at 7.9GHz with a 3mm thickness, and EM absorption properties(RL<-20dB) in the 5.2~16.1GHz range with thickness range of 1.67-4.7mm. The excellent Microwave-absorption properties of as-prepared nanocapsules are ascribed to shape anisotropy and core/shell structure.

Preparation of graphene/Fe3O4/Ni electromagnetic microwave absorbing nano-composite materials

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940055 ◽  
Author(s):  
Yu-Wei Huang ◽  
Yu-Jiang Wang ◽  
Shi-Cheng Wei ◽  
Yi Liang ◽  
Wei Huang ◽  
...  
Keyword(s):  
Composite Materials ◽  
Photoelectron Spectroscopy ◽  
Network Analyzer ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Nano Composite ◽  
X Ray ◽  
Microwave Absorbing Properties ◽  
One Step ◽  
Microwave Absorbing

Graphene/Fe3O4/Ni nano-composite materials were prepared by one-step hydrothermal method from RGO, FeCl3 ⋅ 6H2O and purity Ni. The structure and electromagnetic microwave absorbing properties were investigated systematically by field emission scanning electron microscope (FESEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS) and vector network analyzer (VNA). The reflectance was simulated based on the electromagnetic parameters to evaluate the absorption properties of the sample. The results show that Fe3O4 and Ni are on the surface of graphene evenly, the composites exhibit excellent microwave absorption properties, reflection loss and broad effective absorption bandwidth are −16.38 dB and 3.60 GHz, as the paraffin wax is 40% and the matching thickness is 2.00–3.50 mm.

Enhanced Microwave Absorption Properties of Metal Organic Framework (MOF)-Derived Carbonaceous ZnO Incorporated Reduced Graphene Oxide Composites

NANO ◽  
2019 ◽  
Vol 14 (01) ◽  
pp. 1950005 ◽  
Author(s):  
Zhongfei Liu ◽  
Jiangtao Yuan ◽  
Hui Zhang ◽  
Kuangwei Xiong ◽  
Shaowei Jin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Metal Organic Framework ◽  
X Ray Diffraction ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Transmission Electron ◽  
Reduced Graphene ◽  
Metal Organic ◽  
Oxide Composites

In this paper, the MOFs-derived carbonaceous ZnO and RGO (carbonaceous ZnO/RGO) composites have been prepared by the wet chemical method and carbonization process. The as-prepared products are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), Raman spectra, thermogravimetric (TG) analysis and X-ray photoelectron spectroscopy (XPS). The electromagnetic parameters of carbonaceous ZnO/RGO composites are investigated by the vector network analyzer. The results exhibit carbonaceous ZnO/RGO composites have a maximum absorption of [Formula: see text][Formula: see text]dB at 6[Formula: see text]GHz with thickness of 3.5[Formula: see text]mm and the effective absorption (below [Formula: see text][Formula: see text]dB) bandwidth is up to 1.92[Formula: see text]GHz (from 5.28 to 7.2[Formula: see text]GHz). Thus, the carbonaceous ZnO/RGO composites have great potential in the field of electromagnetic wave absorption.

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 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 of Ce1−xPdxO2−δ Solid Solution in Molten Nitrate

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 640
Author(s):  
Hideaki Sasaki ◽  
Keisuke Sakamoto ◽  
Masami Mori ◽  
Tatsuaki Sakamoto
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Solid Solutions ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Ionic States

CeO2-based solid solutions in which Pd partially substitutes for Ce attract considerable attention, owing to their high catalytic performances. In this study, the solid solution (Ce1−xPdxO2−δ) with a high Pd content (x ~ 0.2) was synthesized through co-precipitation under oxidative conditions using molten nitrate, and its structure and thermal decomposition were examined. The characteristics of the solid solution, such as the change in a lattice constant, inhibition of sintering, and ionic states, were examined using X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), transmission electron microscopy (TEM)−EDS, and X-ray photoelectron spectroscopy (XPS). The synthesis method proposed in this study appears suitable for the easy preparation of CeO2 solid solutions with a high Pd content.

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