ACS Applied Polymer Materials
·
2024
·
IF 4.4
Zhendong Ma,Jianshuo Zheng,Chenyue Wang,Pengli Lei,Qiu Zhuang,Weijin Li,Aming Xie
Dielectric loss and magnetic loss are two necessary factors in electromagnetic wave absorption, but there are few works that can study magnetic factors alone because of the limitations of the material itself. This work achieved the transformation from a nonmagnetic polymer (PFc-1) to a superparamagnetic polymer (PFc-3) by introducing alkyne units to regulate the valence state of iron atoms in the ferrocene unit. It also accomplished the transition of wave-absorbing properties from nonexistent to present. The extremely low dielectric loss of the polymer itself also provides a good background for studying magnetic losses. After characterization, the maximum reflection loss of PFc-3 under the action of exchange resonance reaches −31.7 dB. Through density functional theory (DFT) calculations, we can speculate on the specific mechanism of exchange resonance in PFc-3: under the influence of specific external sources, the single-electron energy level structure of Fe changes. The frequency jumps, creating a resonance. This work opens up a perspective for the application of magnetic regulation in the field of electromagnetic absorption.
研究领域:
材料科学
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电磁学
·
计算化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Bo Wei,Congyu Zhou,Zhengjun Yao,Linling Xu,Zhejia Li,Li Wan,Jinsen Hou,Jintang Zhou
Due to the excessively high electrical conductivity and single dielectric properties of the graphene material, when used as a wave absorbing material, the imbalance of impedance matching causes strong reflection effects, resulting in poor wave absorbing performance. In this research, we partially reduced graphene oxide (GO) and loaded magnetic quantum dots (MQDs) through a one-step pyrolysis method, and a novel composite material of three MQDs (Fe, Fe 3 O 4 , Fe 3 C) embedded partially reduced graphene oxide (P-rGO) was prepared and the influence of pyrolysis temperature on its electromagnetic performance was systematically studied. The research found that ethylene glycol selectively reduced the C O functional group of the GO component and enhanced its dielectric properties; the loading of MQDs for a single carbon material increased the magnetic loss mechanism and improved the impedance matching and attenuation capabilities. In addition, the flaky structure of GO and the ultra-small nanostructure of MQDs suppress the eddy current effect and promote the occurrence of exchange resonance between magnetic particles. The prepared four sets of samples exhibit excellent absorbing properties in the 2–18 GHz frequency band. Among them, the samples prepared by pyrolysis at 800 °C can obtain 5.59 GHz broadband electromagnetic wave absorption at an ultra-thin thickness of 1.7 mm. The special quantum size effect and enhanced electromagnetic wave attenuation capabilities are the main reasons for the high-efficiency microwave absorption of MQDs/P-rGO composite materials.
研究领域:
材料科学
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电磁学
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Yongpeng Wang,Yingyuan Zhang,Jianan Tao,Wei Sun,Mengzhu Liu,Xuejun Cui,Haibo Zhang,Zhenhua Jiang
High-performance electromagnetic (EM) wave absorption property could be achieved by architecture design of nanomaterials . Herein, two layer hybrid Co 0.2 Fe 2.8 O 4 /carbon nanofibers with porous three-dimensional (3D) hierarchical structure were synthesized successfully through facile electrospinning, carbonization and mild chemical treatment. The Co 0.2 Fe 2.8 O 4 particles grew along the carbon nanofibers , forming the enhanced heterogeneous interfaces and high specific areas. As expected, the EM wave absorbent showed an excellent absorbing capability. The composites achieved a maximum reflection loss (RL) of −43.45 dB at 11.1 GHz with thickness of 3.0 mm. More importantly, the effective bandwidth (RL ≤ −10dB) was 5.85 GHz, covering 30% of the entire measured bandwidth. The absorption intensity and bandwidth were superior to other typical CoFe-based composites. The intrinsic mechanism of the absorption revealed that the polarization losses, magnetic losses, magnetic natural resonance and exchanged resonance losses contributed to the high-performance microwave absorption. Moreover, good impedance matching and complex transmission paths that generated from unique porous network also played an important role. This study is expected to guide future exploration on designing and synthesizing high performance EM wave absorbents.
研究领域:
材料科学
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电磁学
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纳米技术
·
复合材料
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产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2021
·Vol. 9
·期 7
·2474-2482
·
IF 7.393
Jiyong Fang,Peng Li,Yidong Liu,Yonggang Min
Two kinds of magnetic particle and cotton-based carbon composite absorbers (PCMT/Co and CMT/Co) were synthesized based on a chemical component and morphology design principle. As confirmed by scanning electron microscopy, CMT/Co has a microtube-like structure, while PCMT/Co has a hierarchically porous microtube-like structure. Co metal particles which are encapsulated in the tubular-structure and the carbon matrix were used to improve the electromagnetic matching condition and bring magnetic loss ability. The porous and hollow structure can reduce the material's density and bring more interfaces. Therefore, through the Debye dipolar relaxation and interfacial polarization-induced dielectric loss together with the exchange resonance-induced magnetic loss, electromagnetic waves can be rapidly attenuated inside PCMT/Co and CMT/Co. At a matching thickness of 1.4 mm, PCMT/Co shows a reflection loss (RL) of −36.8 dB and an effective attenuation bandwidth (EABW, RL < −10 dB) of 6.7 GHz, while CMT/Co achieves a minimum RL value of −31.2 dB and EABW of 5.5 GHz. Considering the preparation procedure and the raw material source, PCMT/Co and CMT/Co may become promising candidates in the field of EMW absorption due to their thin matching thickness, wider bandwidth absorption, low cost and ease of synthesis.
研究领域:
材料科学
·
电磁学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
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