Intense nonlinear dielectric and magnetic resonances of core–shell Ni@graphene composites and their improved microwave absorption properties

2021 ◽  
Vol 9 (14) ◽  
pp. 4910-4920
Author(s):  
Ying Liu ◽  
Xiaoyu Zhang ◽  
Xin Chen ◽  
Yanxia Wu ◽  
Caili Zhang ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Core Shell ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Band Frequency ◽  
Nonlinear Dielectric ◽  
Magnetic Resonances ◽  
Ku Band

Core/shell Ni@graphene composites are prepared by an in situ CVD process using PMMA precursors. The composites exhibit intense nonlinear dielectric and magnetic resonances at Ku-band frequency range, which are benefit to the absorption of microwave.

Enhanced Microwave Absorption Properties of FeCo@TiO2 Core-Shell Nanoparticles

2018 ◽  
Vol 15 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Abdolrasoul Gharaati ◽  
Majid Ebrahimzadeh
Keyword(s):  
Tio2 Nanoparticles ◽  
Microwave Absorption ◽  
Core Shell ◽  
Frequency Range ◽  
Absorption Properties ◽  
Shell Nanoparticles ◽  
Microwave Absorption Properties ◽  
Band Frequency ◽  
Microwave Absorbing ◽  
Core Shell Nanoparticles

Background: Microwave absorbing nanocomposite is a kind of material that attenuates the reflection of microwave radiation in the gigahertz frequency range. These materials consist of dielectric and transition nanoparticles tend to exhibit attractive microwave absorption properties due to their high permittivity and permeability loss factors. Method: The FeCo nanoparticles were prepared from the reduction of iron and cobalt ions with hydrazine. Then, the FeCo@TiO2 core-shell nanoparticles synthesized by co-precipitation method and their microwave absorbing performance are investigated. The phase composition, morphology and coercivity properties of the nanoparticles were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The composites of FeCo@TiO2 nanoparticles with the ratio of 30 vol.% and paraffin wax (70 vol.%) in different thicknesses were prepared. The microwave absorption properties of these composites were investigated in the frequency range of 2-18 GHz using the vector network analyzer. Results: These nanocomposites exhibit the excellent microwave absorption characteristics (reflection loss<-20dB) in the bored band frequency range of 6-16 GHz with different absorber thicknesses of 1- 2.2 mm. The maximum absorption capability of -47.76 dB was obtained at the frequency of 7.92 GHz with the thickness of 1.8 mm. Based on this study, it can be argued that the FeCo@TiO2 nanoparticles can be used for the bored band and thin microwave absorbers.

scholarly journals Preparation and Characterization of CuFe2O4 Nanoparticles by the Sol-Gel Method and Investigation of Its Microwave Absorption Properties at Ku-Band Frequency Using Silicone Rubber

Proceedings ◽  
2018 ◽  
Vol 2 (17) ◽  
pp. 1155 ◽  
Author(s):  
Reza Peymanfar ◽  
Farzaneh Azadi ◽  
Yousef Yassi
Keyword(s):  
Microwave Absorption ◽  
Silicone Rubber ◽  
Electromagnetic Waves ◽  
Sol Gel ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Band Frequency ◽  
Gel Method ◽  
Sol Gel Method ◽  
Ku Band

Recently, using microwave devices that emit electromagnetic waves and enhance the convenience of life have increased; however, they can be harmful to the environment. In this study, CuFe2O4 nanoparticles were prepared through the conventional sol-gel procedure and then were characterized by X-ray powder diffraction (XRD), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and vector network analyzer (VNA) using S parameters. Results illustrated that pure crystal structure of magnetic nanoparticles has been synthesized by the sol-gel method with magnetic saturation (Ms) of 22 emu/g. Finally, CuFe2O4 nanoparticles were composited by silicone rubber to investigate its microwave absorption properties. Results showed that the CuFe2O4/silicone rubber nanocomposite absorbed more than 94.87% of the microwave irradiation at ku-band frequency with 1.7 mm thickness and the maximum reflection loss was −60.38 dB at 16.1 GHz. Magnetic and dielectric properties of the CuFe2O4 nanoparticles and silicone rubber polymeric matrix in the nanocomposite demonstrated desirable microwave absorption properties.

scholarly journals Synthesis and Microwave Absorption Properties of Core-Shell Structured Co3O4-PANI Nanocomposites

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Hongyan Xu ◽  
Zhenyin Hai ◽  
Jiangtao Diwu ◽  
Qiang Zhang ◽  
Libo Gao ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
In Situ Polymerization ◽  
Low Cost ◽  
Core Shell ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
The Core ◽  
High Efficient

The core-shell structured Co3O4-PANI nanocomposites have been successfully prepared using an in situ polymerization method, while the core Co3O4 nanoparticles were synthesized by carbon-assisted method using degreasing cotton as a template. The obtained samples were characterized by XRD, TEM, FTIR, and XPS. The results indicated that the amorphous PANI was well covered on the surface of the spinel Co3O4 and the Co3O4-PANI with core-shell structure was formed with particle size of about 100 nm. The interfacial interaction of the core-shell nanocomposite greatly enhances the microwave absorption properties. The maximum reflection loss of Co3O4-PANI is up to −45.8 dB at 11.7 GHz with a thickness of 2.5 mm and the adsorption bandwidth with the reflection loss below −10 dB reaches 14.1 GHz ranging from 3.9 to 18 GHz when the thickness is between 2 and 5.5 mm. Therefore, the facilely synthesized and low-cost Co3O4-PANI nanocomposite with superior microwave absorption properties can be a promising nanomaterial for high efficient microwave absorption.

Microwave Absorption Properties of Fe3O4-Graphene Nanohybrids

2017 ◽  
Vol 268 ◽  
pp. 297-301 ◽  
Author(s):  
Yau Thim Ng ◽  
Wei Kong ◽  
Sivanesan Appadu ◽  
Ing Kong
Keyword(s):  
Microwave Absorption ◽  
Magnetic Loss ◽  
Impedance Matching ◽  
Low Frequency ◽  
Electromagnetic Properties ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
In Situ Deposition

Magnetite (Fe3O4)-graphene nanohybrids having three different weight ratios of magnetite to graphene were synthesized by a facile in-situ deposition method. The combination of dielectric properties of graphene and magnetic properties of magnetite makes the nanohybrids an ideal choice of material for microwave absorption applications. In regards to that, the electromagnetic properties and microwave absorbing characteristics were investigated in a frequency range of 1-18 GHz. The reflection loss (RL) reaches a minimum of-40.44 dB at 6.84 GHz with a thickness of 7 mm for the sample containing 73 wt·% of Fe3O4. The bandwidth corresponding to the RL below-10 dB is 7.05 GHz. The as-prepared Fe3O4-graphene nanohybrids showed good microwave absorption ability in the low frequency band (C-band) which can be ascribed to improved impedance matching characteristics, enhanced interfacial polarizations as well as the magnetic loss contributions. Moreover, the frequency related to minimum RL could be tuned by varying the weight ratios of magnetite to graphene.

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