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.

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.

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, 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.

scholarly journals Facile preparation and excellent microwave absorption properties of an RGO/Co0.33Ni0.67 lightweight absorber

RSC Advances ◽  
2017 ◽  
Vol 7 (69) ◽  
pp. 43831-43838 ◽  
Author(s):  
Hai Pan ◽  
Mingzhen Xu ◽  
Qing Qi ◽  
Xiaobo Liu
Keyword(s):  
Microwave Absorption ◽  
Reduction Process ◽  
Thermal Reduction ◽  
Thermal Method ◽  
Absorption Properties ◽  
One Pot ◽  
Microwave Absorption Properties ◽  
Facile Preparation

A lightweight absorber with an ordered sandwich-like structure was fabricated using a simple one-pot solvent-thermal method and thermal reduction process.

Large-Scale Synthesis and Microwave Absorption Properties of CoFe2O4/ Co0.4Zn0.6Fe2O4 Hollow Nanospheres

2015 ◽  
Vol 645-646 ◽  
pp. 126-131
Author(s):  
Qing Guo Ren ◽  
Xiao Jing Qiao ◽  
Yan Li ◽  
Zhi Gang Sun ◽  
Xiao Dang Guo ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
Large Scale ◽  
Average Diameter ◽  
Hollow Nanospheres ◽  
Magnetic Studies ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Line Theory ◽  
Glycol Solution

Monodisperse CoFe2O4and Co0.4Zn0.6Fe2O4hollow nanospheres were synthesized in large scale by solvothermal method in ethylene glycol solution. The structure, shape and size of the samples were investigated by Fourier Transform infrared, X-ray powder diffraction and scanning electron microscopy. The results indicate that the products are spherical with an average diameter less than 200 nm. Magnetic studies revealed that the saturation magnetization of Co0.4Zn0.6Fe2O4is 78.6 emu/g, higher than the CoFe2O4, which is 69 emu/g, while the coercivity of the Co0.4Zn0.6Fe2O4is 184 Oe , obviously lower than that of CoFe2O4which is 832 Oe. The electromagnetic parameters were measured at 2-18 GHz using HP8722ES vector network analyzer and then the microwave absorption properties were calculated through the transmission line theory. As to the Co0.4Zn0.6Fe2O4, the absorption bandwidth with reflection loss below-10 dB is up to 3GHz, from 10GHz to 13GHz with a thickness of 2 mm. A maximum reflection loss-45.6 dB was found at 12.9 GHz for the CoFe2O4with a thickness of 1.8 mm. As a result, the as-prepared hollow nanospheres show good prospects of being applied in EM wave absorption materials.

One-Pot Synthesis of (NiFe2O4)x–(SrFe12O19)1−x Nanocomposites and Their Microwave Absorption Properties

2015 ◽  
Vol 15 (9) ◽  
pp. 6559-6567 ◽  
Author(s):  
Subhenjit Hazra ◽  
Barun Kumar Ghosh ◽  
Manoj Kumar Patra ◽  
Raj Kumar Jani ◽  
Sampat Raj Vadera ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Absorption Properties ◽  
One Pot ◽  
Microwave Absorption Properties ◽  
One Pot Synthesis
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