scholarly journals 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

2020 ◽  
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.

scholarly journals Enabling highly efficient and broadband electromagnetic wave absorption by tuning impedance match in high-entropy transition metal diborides (HE TMB2)

2021 ◽  
Author(s):  
Weiming Zhang ◽  
Fu-Zhi Dai ◽  
Huimin Xiang ◽  
Biao Zhao ◽  
Xiaohui Wang ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Transition Metal ◽  
Impedance Match ◽  
Magnetic Losses ◽  
High Entropy ◽  
Wave Absorption ◽  
Highly Efficient ◽  
Absorbing Materials ◽  
Metal Diborides ◽  
Transition Metal Diborides

AbstractThe advance in communication technology has triggered worldwide concern on electromagnetic wave pollution. To cope with this challenge, exploring high-performance electromagnetic (EM) wave absorbing materials with dielectric and magnetic losses coupling is urgently required. Of the EM wave absorbers, transition metal diborides (TMB2) possess excellent dielectric loss capability. However, akin to other single dielectric materials, poor impedance match leads to inferior performance. High-entropy engineering is expected to be effective in tailoring the balance between dielectric and magnetic losses through compositional design. Herein, three HE TMB2 powders with nominal equimolar TM including HE TMB2-1 (TM = Zr, Hf, Nb, Ta), HE TMB2-2 (TM = Ti, Zr, Hf, Nb, Ta), and HE TMB2-3 (TM = Cr, Zr, Hf, Nb, Ta) have been designed and prepared by one-step boro/carbothermal reduction. As a result of synergistic effects of strong attenuation capability and impedance match, HE TMB2-1 shows much improved performance with the optimal minimum reflection loss (RLmin) of −59.6 dB (8.48 GHz, 2.68 mm) and effective absorption bandwidth (EAB) of 7.6 GHz (2.3 mm). Most impressively, incorporating Cr in HE TMB2-3 greatly improves the impedance match over 1–18 GHz, thus achieving the RLmin of −56.2 dB (8.48 GHz, 2.63 mm) and the EAB of 11.0 GHz (2.2 mm), which is superior to most other EM wave absorbing materials. This work reveals that constructing high-entropy compounds, especially by incorporating magnetic elements, is effectual in tailoring the impedance match for highly conductive compounds, i.e., tuning electrical conductivity and boosting magnetic loss to realize highly efficient and broadband EM wave absorption with dielectric and magnetic coupling in single-phase materials.

scholarly journals One-step hydrothermal synthesis of Ni–Fe–P/graphene nanosheet composites with excellent electromagnetic wave absorption properties

RSC Advances ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 5570-5581 ◽  
Author(s):  
Shuo Zhao ◽  
Chunyu Wang ◽  
Ting Su ◽  
Bo Zhong
Keyword(s):  
Electromagnetic Wave ◽  
Excellent Performance ◽  
Absorption Properties ◽  
Graphene Nanosheet ◽  
Absorption Bandwidth ◽  
Electromagnetic Wave Absorption ◽  
Wave Absorption ◽  
One Step ◽  
5 Ghz ◽  
Minimum Reflection Loss

Ni–Fe–P nanoparticle/graphene nanosheet composites synthesized by a one-step hydrothermal method have excellent performance in the field of electromagnetic wave absorption, with a minimum reflection loss of −50.5 dB and a maximum effective absorption bandwidth of 5 GHz.

scholarly journals Enhanced electromagnetic wave absorption property of binary ZnO/NiCo2O4 composites

2021 ◽  
Author(s):  
Bin Du ◽  
Mei Cai ◽  
Xuan Wang ◽  
Junjie Qian ◽  
Chao He ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Dielectric Properties ◽  
Hydrothermal Reaction ◽  
Absorption Property ◽  
Absorption Properties ◽  
Promising Candidate ◽  
Electromagnetic Wave Absorption ◽  
Wave Absorption ◽  
Absorbing Materials ◽  
Minimum Reflection Loss

AbstractNowadays, metal oxide-based electromagnetic wave absorbing materials have aroused widely attentions in the application of telecommunication and electronics due to their selectable mechanical and outstanding dielectric properties. Herein, the binary ZnO/NiCo2O4 nanoparticles were successfully synthesized via hydrothermal reaction and the electromagnetic wave absorption properties of the composites were investigated in detail. As a result, benefiting from the dielectric loss, the as-obtained ZnO/NiCo2O4-7 samples possessed a minimum reflection loss value of −33.49 dB at 18.0 GHz with the thickness of 4.99 mm. This work indicates that ZnO/NiCo2O4 composites have the promising candidate applications in electromagnetic wave absorption materials in the future.

Millimeter-wave absorption properties of BaTiO3/Co3O4 composite powders controlled by high-frequency resonances of permittivity and permeability

2018 ◽  
Vol 6 (47) ◽  
pp. 12965-12975 ◽  
Author(s):  
Wei Tian ◽  
Ruoyang Ma ◽  
Jian Gu ◽  
Zongrong Wang ◽  
Ning Ma ◽  
...  
Keyword(s):  
Millimeter Wave ◽  
High Frequency ◽  
Composite Powders ◽  
Absorption Properties ◽  
Wave Absorption ◽  
Wave Resonance ◽  
Permittivity And Permeability ◽  
5 Ghz

Millimeter-wave resonance of permittivity–permeability-contributed double absorption peaks in BaTiO3/Co3O4, exhibiting RL of ∼−40 dB and a bandwidth of 5 GHz around 35 GHz.

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

RSC Advances ◽  
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.

scholarly journals Spawns Structure of Rod-Like ZnO Wrapped in Cellulose Nanofibers for Electromagnetic Wave Absorption

2017 ◽  
Vol 2017 ◽  
pp. 1-6
Author(s):  
Bitao Fan ◽  
Qiufang Yao ◽  
Chao Wang ◽  
Ye Xiong ◽  
Qingfeng Sun ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Reflection Loss ◽  
Cellulose Nanofibers ◽  
Absorption Properties ◽  
Composite Aerogel ◽  
Electromagnetic Wave Absorption ◽  
Wave Absorption ◽  
One Step ◽  
Absorption Performance ◽  
Minimum Reflection Loss

Spawns structure of rod-like ZnO wrapped in the cellulose nanofibers was successfully fabricated through a facile one-step hydrothermal method, and their electromagnetic wave absorption properties were investigated. The structure and properties of the composite aerogel were characterized. The enlarged morphology images showed that the as-prepared cellulose nanofiber/ZnO samples were spawns structure of rod-like ZnO wrapped in the cellulose nanofibers. The composite aerogel in a wax matrix exhibited excellent electromagnetic wave absorption performance over 2–18 GHz. The widest absorption bandwidth of 30 wt% contained with reflection loss values less than −10 dB was up to 12 GHz (6–18 GHz) at the thickness of 5.5 mm and the minimum reflection loss value reached −26.32 dB at 15.2 GHz when the thickness of the absorber was 3 mm.

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