Achieving super-broad effective absorption bandwidth with low filler loading for graphene aerogels/raspberry-like CoFe2O4 clusters by N doping

In this study, we have successfully synthesized porous CoO–Co@RGO composites using GO and Co-based metal-organic frameworks (MOFs) as precursors. Due to particular structures and advantageous characteristics, the synthesized porous CoO–Co@RGO composites exhibit outstanding electromagnetic (EM) wave absorbing properties with a filler loading of 10[Formula: see text]wt.% in wax matrix. The maximum reflection loss (RL) of the prepared porous CoO–Co@RGO was [Formula: see text][Formula: see text]dB with 2.1[Formula: see text]mm thickness, and the effective absorption bandwidth as wide as 6.24[Formula: see text]GHz (11.76–18[Formula: see text]GHz), which covers the full Ku-band. Remarkably, the achieved all values of[Formula: see text]RL were under [Formula: see text][Formula: see text]dB with 1.0–5.0[Formula: see text]mm thickness, the corresponding to bandwidth range can be tuned to 13.84[Formula: see text]GHz (4.16–18[Formula: see text]GHz). The superior absorbing performance is attributed to suitable magnetic loss, high dielectric loss and large attenuation mainly caused by conduction loss and polarization relaxation.

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Electromagnetic and microwave absorption properties of iron pentacarbonyl pyrolysis-synthesized carbonyl iron fibers

RSC Advances ◽

10.1039/d0ra00222d ◽

2020 ◽

Vol 10 (40) ◽

pp. 23702-23711

Author(s):

Chaoqun Ge ◽

Liuying Wang ◽

Gu Liu ◽

Kejun Xu ◽

Long Wang ◽

...

Keyword(s):

Microwave Absorption ◽

Carbonyl Iron ◽

Iron Pentacarbonyl ◽

Absorption Properties ◽

Microwave Absorption Properties ◽

Absorption Bandwidth ◽

Effective Absorption

Carbonyl iron fibers synthesized at 300 °C exhibit a minimum RL of −58.1 dB and an effective absorption bandwidth of 5.66 GHz.

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The Effect of Solvothermal Conditions on the Properties of Three-Dimensional N-Doped Graphene Aerogels

Nanomaterials ◽

10.3390/nano9030350 ◽

2019 ◽

Vol 9 (3) ◽

pp. 350 ◽

Cited By ~ 5

Author(s):

Alina Pruna ◽

Alfonso Cárcel ◽

Adolfo Benedito ◽

Enrique Giménez

Keyword(s):

Ring Opening ◽

Operating Temperature ◽

Three Dimensional ◽

Low Density ◽

Epoxy Ring ◽

Graphene Aerogels ◽

N Doping ◽

Epoxy Ring Opening ◽

Doped Graphene ◽

Solvothermal Conditions

Low-density three-dimensional (3D) N-doped graphene aerogels by a one-step solvothermal method in the presence of ethylenediamine (EDA) are reported. The gelation, formation, and properties of the aerogels were studied with solvothermal conditions, namely, operating temperature, time, graphene oxide (GO) concentration, and the GO/EDA w/w ratio. Two ranges of solvothermal conditions are employed: one involving an operating temperature below 100 °C and a conventional chemical reduction of GO with EDA at atmospheric pressure and a second one employing a higher temperature range up to 165 and a high pressure reduction with EDA. The results show that both solvothermal approaches allow for the fabrication of homogeneous N-doped 3D graphene aerogels with density values close to 10 mg cm−3. The measurements indicated that low values of GO concentration, temperature, and EDA are optimum for obtaining low-density 3D aerogels. N doping is improved with an EDA amount in lower temperature conditions. The N doping mechanism below 100 °C is dominated by the epoxy ring opening while at temperatures up to 165 °C both epoxy ring opening and amidation take place. The CO2 adsorption properties are strongly controlled by the nitrogen configuration, namely, pyridinic nitrogen in terms of its density.

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Hollow porous Fe2O3 microspheres wrapped by reduced graphene oxides with high-performance microwave absorption

Journal of Materials Chemistry C ◽

10.1039/c9tc03691a ◽

2019 ◽

Vol 7 (36) ◽

pp. 11167-11176 ◽

Cited By ~ 18

Author(s):

Lei Wang ◽

Jie Zhang ◽

Min Wang ◽

Renchao Che

Keyword(s):

Microwave Absorption ◽

Reflection Loss ◽

High Performance ◽

Graphene Oxides ◽

Absorption Bandwidth ◽

Effective Absorption ◽

Reduced Graphene ◽

Reduced Graphene Oxides

Hollow porous Fe2O3 microspheres wrapped by thin RGO sheets exhibited high-performance microwave absorption with a reflection loss value of −48.1 dB and an effective absorption bandwidth cover of 5.28 GHz.

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Facile design of a ZnO nanorod–Ni core–shell composite with dual peaks to tune its microwave absorption properties

RSC Advances ◽

10.1039/c6ra28835a ◽

2017 ◽

Vol 7 (15) ◽

pp. 9294-9302 ◽

Cited By ~ 71

Author(s):

Jiushuai Deng ◽

Qibiao Wang ◽

Yuanyuan Zhou ◽

Biao Zhao ◽

Rui Zhang

Keyword(s):

Microwave Absorption ◽

Core Shell ◽

Zno Nanorod ◽

Absorption Bands ◽

Absorption Properties ◽

Microwave Absorption Properties ◽

Absorption Bandwidth ◽

Effective Absorption ◽

Shell Composite

The Ni/ZnO composites show two wide attractive absorption bands, which could broaden the effective absorption bandwidth.

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One-step synthesis and electromagnetic absorption properties of high entropy rare earth hexaborides (HE REB6) and high entropy rare earth hexaborides/borates (HE REB6/HE REBO3) composite powders

Journal of Advanced Ceramics ◽

10.1007/s40145-020-0417-2 ◽

2020 ◽

Cited By ~ 1

Author(s):

Weiming Zhang ◽

Biao Zhao ◽

Huimin Xiang ◽

Fu-Zhi Dai ◽

Shijiang Wu ◽

...

Keyword(s):

Rare Earth ◽

Magnetic Losses ◽

Composite Powders ◽

Absorption Properties ◽

Absorption Bandwidth ◽

High Entropy ◽

Wave Absorption ◽

Effective Absorption ◽

Absorbing Materials ◽

One Step

Abstract Considering the emergence of severe electromagnetic interference problems, it is vital to develop electromagnetic (EM) wave absorbing materials with high dielectric, magnetic loss and optimized impedance matching. However, realizing the synergistic dielectric and magnetic losses in a single phase material is still a challenge. Herein, high entropy (HE) rare earth hexaborides (REB6) powders with coupling of dielectric and magnetic losses were designed and successfully synthesized through a facial one-step boron carbide reduction method, and the effects of high entropy borates intermedia phases on the EM wave absorption properties were investigated. Five HE REB6 ceramics including (Ce0.2Y0.2Sm0.2Er0.2Yb0.2)B6, (Ce0.2Eu0.2Sm0.2Er0.2Yb0.2)B6, (Ce0.2Y0.2Eu0.2Er0.2Yb0.2)B6, (Ce0.2Y0.2Sm0.2 Eu0.2Yb0.2)B6, and (Nd0.2Y0.2Sm0.2Eu0.2 Yb0.2)B6 possess CsCl-type cubic crystal structure, and their theoretical densities range from 4.84 to 5.25 g/cm3. (Ce0.2Y0.2Sm0.2Er0.2 Yb0.2)B6 powders with the average particle size of 1.86 µm were found to possess the best EM wave absorption properties among these hexaborides. The RLmin value of (Ce0.2Y0.2Sm0.2Er0.2Yb0.2)B6 reaches −33.4 dB at 11.5 GHz at thickness of 2 mm; meanwhile, the optimized effective absorption bandwidth (EAB) is 3.9 GHz from 13.6 to 17.5 GHz with a thickness of 1.5 mm. The introduction of HE REBO3 (RE = Ce, Y, Sm, Eu, Er, Yb) as intermediate phase will give rise to the mismatching impedance, which will further lead to the reduction of reflection loss. Intriguingly, the HEREB6/HEREBO3 still possess wide effective absorption bandwidth of 4.1 GHz with the relative low thickness of 1.7 mm. Considering the better stability, low density, and good EM wave absorption properties, HE REB6 ceramics are promising as a new type of EM wave absorbing materials.

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Novel ceramic-based microwave absorbents derived from gangue

Journal of Materials Chemistry C ◽

10.1039/d0tc03633a ◽

2020 ◽

Vol 8 (40) ◽

pp. 14238-14245

Author(s):

Guomin Li ◽

Lutao Mao ◽

Baoshun Zhu ◽

Xin Chang ◽

Yake Wang ◽

...

Keyword(s):

Microwave Absorption ◽

Reflection Loss ◽

High Performance ◽

Absorption Bandwidth ◽

Effective Absorption

Compared with gangue, FeG700 exhibited high-performance microwave absorption with a reflection loss of −41.9 dB and an effective absorption bandwidth of 4.1 GHz.

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