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1.
Chunyang Xu Kaicheng Luo Yiqian Du Huibin Zhang Xiaowei Lv Hualiang Lv Ruixuan Zhang Chang Zhang Jincang Zhang Renchao Che 《Advanced functional materials》2023,33(47):2307529
The fabrication of nanometer-sized magnetic heterostructures with controlled magnetic components and specific interfaces holds great significance in the field of electromagnetic (EM) wave absorption. However, the process of achieving these structures still poses significant challenges. Here, abundant magnetic heterostructures are successfully fabricated by utilizing the surface energy anisotropy differences of the nonasymmetric hammer-shaped interface to support the nucleation and growth of magnetic heterostructure components while effectively inhibiting their aggregation. Through a confined growth strategy via in situ growth of FeOOH and sequentially precise thermal treatments, dispersion of the heterostructures is achieved at the nanometer scale, while also observing a high degree of chemical stability due to occurrence of a charge-compensation effect at the interface. Consequently, a series of magnetic heterostructures are obtained via phase translations of FeOOH precursors. The nanometer-sized heterostructures demonstrate multilevel interfacial polarization effects. Furthermore, the hierarchical core–shell structure of the heterostructures promotes anisotropic polarization absorption. As a result, the multiple interfaces and nanometer-sized Fe/Fe3O4@SiO2@Fe-2 heterostructures demonstrate improved EM wave attenuation performance. Remarkably, they achieve an absorption bandwidth of 9 GHz at a thickness of 1.8 mm. A novel avenue is introduced here for investigating the intricate relationship between structure and properties in magnetic heterostructures. 相似文献
2.
Rational manipulation of multimetal hybrid materials (HMs) with tunable substitution or phases is evolving as an effective strategy to meet the controllable electromagnetic (EM) properties and EM wave (EMW) absorption. Herein, a new thermodynamic and kinetic cocontrol strategy is proposed to construct Zn/Co bimetal HMs with tuning ion and phase hybridization for synergistic effect on EM properties for the first time. Auxiliary chelating agent triethanolamine (TEA) dominates the phase separation by stepwise Zn/Co deposition in metal–organic frameworks, then the pyrolysis process under gradient temperature give rise to controllable ion hybridization products due to thermal motion. Benefiting from the tunable collaboration between defects polarization and interfacial polarization, the 700 °C HMs exhibit ultrahigh EM parameters and EMW absorption, of which products with no TEA deliver the effective absorbing bandwidth of 4.80 GHz (1.6 mm) and minimum reflection loss of −45.85 dB. The results indicated that synergistic effect of ion and phase hybridization can improve the defects induced “polarization centers” and coherent interfaces induced interfacial polarization. Furthermore, the comprehensive research and deep understanding on respective contribution of hybridization forms provide a precise inspiration in developing bimetal and even multimetal ferrite with tunable hybridization structure. 相似文献
3.
Yan Cheng Huanqin Zhao Hualiang Lv Tengfei Shi Guangbin Ji Yanglong Hou 《Advanced Electronic Materials》2020,6(1)
Currently, a versatile route is urgently required to achieve excellent electromagnetic wave (EMW) absorption and shielding functions simultaneously. A lightweight, flexible and sustainable 3D framework aerogel is designed to reach this goal, which is assembled by unique “1D‐1D” combination, nanoscale carbon nanotubes (CNTs) grown on microscale carbon fiber. EM absorption requires appropriate conductivity of filler to acquire moderate permittivity. On the contrary, EM shielding requires great conductivity to reflect most of the incident EMW. Based on this design concept, the change of electric conductivity of as‐obtained samples through in situ regulation of the growth state of CNTs is successfully controlled. When the CNTs are short and curly, the optimized conductivity favors excellent microwave absorption with wide absorption bandwidth of 5.08 GHz at only 1.6 mm. When the CNTs are long and straight, the increased conductivity is clearly boosted with 29.8 dB EM shielding effectiveness. This elaborate architecture and controlled CNT growth allow the designed 3D framework aerogel to be applied in both EM wave absorption and shielding. This conductivity tunable route gives inspiration for fabricating other efficient EM absorption and shielding devices. 相似文献
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2D materials and their composites with electromagnetic properties are becoming increasingly popular. Obtaining insight into the nature of electromagnetic (EM) response manipulation is imperative to guide scientific research and technological exploitation at such a critical time. From this perspective, the dielectric genes of 2D material hybrids have been highlighted based on the recent literature. This endows an unlimited possibility of manipulating the EM response, even at elevated temperatures. The definitions and criteria of dielectric genes toward 2D material hybrids and composites are systematically clarified and summarized. The dielectric gene categories are successfully discriminated, including the conduction networks, intrinsic defects, impurity defects, and interfaces in the composite, and their temperature evolution is revealed in detail. More importantly, tuning strategies for microwave absorption, electromagnetic shielding effectiveness, and expanded electromagnetic functions are thoroughly discussed. Finally, significant predictions are provided for multispectral electromagnetic functions, and future applications of multifunctional exploration are anticipated. Dielectric genes will open an unexpected horizon for advanced functional materials in the coming 5G/6G age, providing a significant boost to promoting environmental electromagnetic protection, electromagnetic devices, and next-generation smart devices. 相似文献
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Qiang Song Fang Ye Luo Kong Qingliang Shen Liyuan Han Lei Feng Gaojie Yu Yuanan Pan Hejun Li 《Advanced functional materials》2020,30(31)
Searching for advanced microwave absorption (MA) nanomaterials is one of the most feasible ways to address the increasing electromagnetic pollution in both military and civil fields. To this end, graphene and MXene have won the widespread attention as the main representatives due to their remarkable structures and properties. The common features such as the large aspect ratio, active chemical surface, and varieties of synthesis processes endow graphene and MXene with unique superiorities for developing high‐efficiency MA structures, in particular lightweight assemblies and various hybrids. Meanwhile, the structural and performance differences (such as different conductivities) between them result in distinctive techniques in the design, fabrication, and application of their MA materials. Herein, the research progress in graphene‐ and MXene‐based MA materials is reviewed, with a special focus on advances in general strategies. Moreover, through the comparison between graphene‐ and MXene‐based MA materials, their respective advantages in achieving high‐performance MA are presented. Furthermore, the future challenge, research orientation, and prospect for these MA materials are also highlighted and discussed. 相似文献
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为精确计算太赫兹波大气传输吸收衰减,需建立太赫兹波传播路径模型,而后获取沿传播路径的相关变化大气参量,并通过国际电联(ITU)标准计算分段的吸收衰减值,最终进行累加计算得出总的大气衰减量值。受限于气象观测设备及手段,沿传播路径完整的大气参量难以获取。由于地球重力场产生的大气折射效应,电磁波在大气层中传播时其路径呈现曲线弯曲传播。基于区域大气再分析资料集基础数据转化的太赫兹波大气传输衰减精确计算方法,通过ITU标准这个桥梁,在气象数据和大气传输衰减间建立关联关系,最终运用在飞行器太赫兹波地面探测类工程技术上,以预估太赫兹波通信链路的大气吸收衰减值。 相似文献
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Ruiwen Shu Gengyuan Zhang Chao Zhang Yue Wu Jiabin Zhang 《Advanced Electronic Materials》2021,7(2):2001001
Heteroatom nitrogen doping is considered an effective strategy to enhance the electromagnetic wave (EMW) absorption capacity of reduced graphene oxide (RGO). Herein, nitrogen-doped RGO aerogels (NGAs) are synthesized via hydrothermal self-assembly followed by lyophilization processes. Results of micromorphology analysis show that the as-prepared NGAs display unique 3D porous and netlike structure. Moreover, the effects of nitrogen doping and filler contents on EMW absorption properties of NGAs are studied. The as-synthesized NGA with nitrogen content of 9.41 at% and a bulk density of 8.7 mg cm–3 presents the integrated optimal EMW absorption performance. Specifically, the minimum reflection loss of –56.4 dB is achieved and maximum absorption bandwidth of 6.8 GHz is reached, covering the whole Ku band. In addition, the possible EMW absorption mechanisms of obtained NGAs are proposed. Therefore, the as-synthesized NGAs can be exploited as promising high-efficiency and lightweight EMW absorbers. 相似文献
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羰基铁粉作为常见的电磁波吸收涂料,其形貌和含量对电磁波吸收性能有极大影响。为掌握羰基铁粉吸波涂料的介电常数、磁导率等参数随频率的变化规律,制备并测试了不同配比的微米级片状羰基铁粉同轴环样品。测试结果表明:羰基铁粉的最佳质量分数为60%~80%,样品厚度为2 mm、2.5 mm时,反射损耗-10 dB以下的有效吸收频宽分别为7.36 GHz、2.4 GHz,最大反射损耗值分别为-19.612 dB、-27.707 dB。样品厚度增加,最大吸收频率移向低频端。 相似文献
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Yajie Liu Xin Sun Zhiming Song Xiaofang Liu Ronghai Yu 《Advanced Electronic Materials》2021,7(3):2000970
Soft magnetic micro/nanostructures are highly desirable for pursuing excellent magnetic properties and electromagnetic wave (EMW) absorption performance. However, their magnetic loss at high frequency is usually very low due to the sharp drop of permeability, and thus results in a heavy loading in matrix and a large layer thickness, which are not conductive to the development of ultralight and ultrathin EMW absorbers. Here, an ultralight and ultrathin EMW absorber based on a parallel Ni wire array are reported, and an orientation-enhanced strategy to improve EMW absorption performance is proposed. Combining with the finite element simulation, it is found that the parallel orientation of Ni wires with a capacitor-like structure enhances the interfacial polarization, thereby improving dielectric loss. The strong shape anisotropy caused by orientation increases magnetic loss by enhancing magnetic resonances, which further improves impedance matching. The parallel Ni wire array exhibits excellent EMW absorption and achieves the largest specific reflection loss (reflection loss/(thickness × loading)) among magnetic wire-based absorbers. 相似文献
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Jiahao Wang Lei Zhang Junfeng Yan Jiangni Yun Wu Zhao Kun Dai Huan Wang Yushan Sun 《Advanced functional materials》2024,34(37):2402419
MXene, a highly regarded material, has garnered significant attention within the electromagnetic wave (EMW) absorption field. However, the practical application of MXene is limited in harsh environments. Herein, a magic technique strategy of intercalation growth nucleation engineering is employed to prepare multifunctional MXene-based EMW absorption materials. By regularly introducing different metal ions between the layers of MXene, an ultrathin absorber can be achieved by annealing after reacting in specific positions. The synthesized MCFC-69-8 shows hydrophobicity properties and exhibits a large charge-transfer resistance of 18112 Ω cm2 with a low corrosion rate and corrosion rate, indicating a good anti-corrosion property. Through applying a series of mathematical methods, MCFC-69-8 shows 25% relaxation polarization loss and 75% conduction loss, and its relaxation time is linked with the specific type of relaxation polarization loss, resulting in an effective absorption bandwidth (EAB) of 4.9 GHz with an ultra-thin optimal matching thickness of 1.48 mm. Finally, an absorber is built using CST to attain an ultrabroad EAB covering 2–18 GHz. This engineering not only simplifies the intercalation process but also achieves a high-performance and anti-corrosion EMW absorber, providing a valuable perception for realizing thinner MXene-based EMW absorbers in the future. 相似文献
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Longjun Rao Lei Wang Chendi Yang Ruixuan Zhang Jincang Zhang Chongyun Liang Renchao Che 《Advanced functional materials》2023,33(16):2213258
The rational design of magnetic composites has great potential for electromagnetic (EM) absorption, particularly in the low-frequency range of 2–8 GHz. However, the scalable synthesis of such magnetic absorbers with both high magnetic content and good dispersity remains challenging. In this study, a confined diffusion strategy is proposed to fabricate functional magnetic-carbon hollow microspheres. Driven by the ferromagnetic enhanced Kirkendall diffusion effect, the in situ alloying of FeCo nanoparticles is tightly confined in carbon shells, effectively inhibiting magnetic agglomeration. Moreover, the core–shell FeCo–carbon nano-units further assemble into dispersive microscale magnetic-carbon Janus bulges on both the inner and outer surfaces of the hollow microsphere. The optimized hollow FeCo@C microspheres exhibit excellent low-frequency EM wave absorption performance: the minimum reflection loss (RLmin) is −35.9 dB, and the absorption bandwidth covers almost the entire C-band. Systematic investigation reveals that the large size of the magnetic-carbon integration, high–density confined magnetic units, and strong magnetic coupling are essential for enhancing the magnetic loss dissipation of low-frequency EM waves. This study provides a novel strategy for fabricating advanced EM wave absorbers and significant inspiration for investigating the magnetic attenuation mechanism at low frequency. 相似文献
13.
多层蜂窝结构因其优异的吸波性能和高强度结构近来受到广泛关注。 本文针对传统多层蜂窝界面处电磁不连续以及浸渍工艺自身精度低等问题,通过 3D 打印技术制备了一种具有宽频电磁波吸收能力的轻质三层梯度蜂窝结构。中层渐变壁厚蜂窝极大地减少了层与层之间的界面反射,该结构在 2. 92 GHz ~ 18 GHz 内实现反射损耗低于- 10 dB,-10 dB 相对吸波带宽为144%,且密度仅为0. 292 g / cm3。 仿真和实验证明了均匀壁厚蜂窝结构与渐变壁厚蜂窝结构的复合设计可以实现界面的电磁连续性,有效改善了阻抗匹配,并提升了电磁波损耗能力,实现了宽频吸收效果。 相似文献
14.
Longjun Rao Zhengwang Liu Lei Wang Wenbin You Chendi Yang Ruixuan Zhang Xuhui Xiong Liting Yang Huibin Zhang Jincang Zhang Hualiang Lv Renchao Che 《Advanced functional materials》2023,33(47):2306984
Dimensional engineering of appropriate structure is an effective approach to achieve high-performance electromagnetic (EM) wave absorption for magnetic materials. However, controllable modulation of the material configuration and a comprehensive understanding of the relationship between structure and loss mechanism remain challenging. Herein, magnetic CoNi pentagonal nanopagodas (PNPs) are ingeniously tailored using a competition orientation strategy, in which high-density PNPs with sharp corners/edges and hierarchical structure are rooted in situ on the surface of CoNi alloy microsphere. This unique configuration of PNPs originates from the orientation growth of CoNi fivefold twins, which can be effectively regulated by manipulating metal ratio and evolves into flake-, serrated thorn-, prismoid-, and blocks-like morphologies. Optimized CoNi microspheres with high-density PNPs exhibit a broad absorption bandwidth of 6.82 GHz at only 1.8 mm thickness. Cross-scale magnetic coupling networks strengthen magnetic loss ability, magnetocrystalline defects induce dielectric polarization enhancement, which are intuitively confirmed by Lorentz off-axis electron holography and geometric phase analysis. The underlying mechanism of enhanced magnetic interaction in sharp structure is clearly deciphered by micromagnetic simulation. This study provides methodological guidance for dimensional engineering in fabricating hierarchical magnetic structure and significant insights into the morphology-dependent loss mechanism for magnetic EM absorption materials. 相似文献
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基于激子基,采用密度矩阵理论研究了太赫兹场作用下半导体超晶格的子带间动力学过程及光吸收谱。在太赫兹场的驱动下,激子作布洛赫振荡。子带间极化的缓慢变化依赖于太赫兹频率,随着太赫兹频率的增加,子带间极化向下振荡,极化强度降低。以 和 两种超晶格为例进行研究,它们的光吸收谱出现了卫星峰结构,这是由于太赫兹场与万尼尔斯塔克阶梯激子作用的非线性效应产生的。但是就 与 超晶格相比而言,我们研究发现,n<0的激子态与n=0的激子态耦合作用较强使得光吸收谱吻合性较好,n＝0时的激子态吸收光谱出现红移,n>0的激子态光吸收谱中出现的边带效应不是很明显。 相似文献
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Skin effect and high density are the main reasons that restrict the search of lightweight and high-performance metal-based electromagnetic (EM) wave absorbing materials. Although nanostructured metal materials have been fabricated to solve above problems, poor dispersibility and chemical stability issues brought about by high surface energy due to existing nano-size effect. In this work, lightweight Ni foam with NiO/NiFe2O4 in situ growth composites are fabricated by a facile and universal route as an effective alternative to high-performance metal-based EM wave absorber. Impressively, it is found that the foam structure and NiO/NiFe2O4/Ni components can synergistically boost EM wave absorption capacity. In detail, impedance matching from foam structure and energy dissipation from interfacial polarization and defect induced polarization provided by NiO/NiFe2O4 mainly contributes to its ultra-broadband EM wave absorption performance. As a result, the as-prepared sample (0.06 g·cm−3) delivers a wide absorption bandwidth of 14.24 GHz and thin thickness of 0.6 mm, as well as, high specific effective absorption bandwidth of 19444.4 GHz·g−1·cm−2. This work sheds light on the novel view on the synergistic effect of structure and components on EM wave absorption behaviors and demonstrates a new pathway for preparation of lightweight and high-performance metal-based EM wave absorbers. 相似文献
18.
Baojun Wang Wei Wei Fangzhi Huang Fenghua Liu Shikuo Li Hui Zhang 《Advanced functional materials》2024,34(45):2404484
Manipulating the electronic structure and geometric coordination environment of single metal atoms has been considered as promising approach for enhancing dipole polarization and enriching electromagnetic attenuation mechanisms. However, achieving precise control of the dielectric polarization response at atomic scale remains a huge challenge. Herein, a metal-acetate coordination complexes-assisted strategy is proposed to prepare spatially isolated cobalt (Co) atoms embedded in accordion-like nitrogen-doped carbon (NC) matrix. The interactions between metal atoms and NC matrix are carefully tailored through the successive evolution of dispersion states of Co species, ranging from individual atoms to atomic clusters to nanoparticles. Density functional theory reveals that the orbital hybridization between the d electrons of embedded Co atoms and p electrons of coordinated N atoms induces the electron redistribution at N sites, enabling enhanced electric dipole polarization and robust room temperature magnetism (a saturation magnetization of 0.108 emu g−1 at 300 K). Consequently, Co-SAs@NC exhibits optimal electromagnetic wave absorption properties with a minimum reflection loss of -54.4 dB and an effective absorption bandwidth of 8.4 GHz. This work demonstrates an efficient strategy for modulating electromagnetic response at atomic level and provides a novel insight into the d/p electrons orbital hybridization between single metal atoms and NC species. 相似文献
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Herein, transition metal chalcogenides of pristine cobalt sulfides are rationally designed to act as robust bifunctional photocatalysts for visible‐light‐driven water splitting for the first time. Through moderate solvothermal route, cobalt sulfides are synthesized in situ growth and observed by scanning electron microscope image analysis. Noteworthily, 3D hierarchical cobalt sulfides acting as bifunctional photocatalysts are implemented to catalyze the visible‐light‐driven oxygen evolution reaction and hydrogen evolution reaction. This efficient, earth‐abundant, and nonnoble water splitting catalyst for artificial photosynthesis is thoroughly analyzed by various spectroscopic techniques with the aim of investigating its photocatalytic mechanism under visible‐light illumination. The main catalyst of CoS‐2 exhibits considerable H2 evolution rate of 1196 µmol h?1 g?1 and O2 yield of 63.5%. The efficient activity is attributed to the effective electron transfer between the photosensitizer and catalyst, which is verified by transient absorption experiments. The effective electron transfer between the photosensitizer and catalyst during water oxidation is verified by the dramatic decline of [Ru(bpy)3]3+ concentration in the presence of the catalyst CoS‐2. At the same time, transient absorption experiments support a rapid electron transfers from 3EY* (excited photosensitizer eosin‐Y) to the catalyst CoS‐2 for efficient hydrogen evolution. 相似文献
20.
Xinci Zhang Bei Li Jia Xu Xiao Zhang Yanan Shi Chunling Zhu Xitian Zhang Yujin Chen 《Advanced functional materials》2023,33(7):2210456
Nanocarbons with single-metal atoms (M-SAs) have displayed considerable potential in various fields of application due to high free energy of M-SAs and strong metal-support interaction. However, the uniform dispersion of M-SAs within the whole carbon matrix still remains a great challenge. Herein, Ni-SAs are uniformly dispersed within hierarchically porous carbon nanoflowers (Ni-SA/HPCF) via a spatial confinement of Ni ions within the periodic pores in metal-organic frameworks (MOFs) with a subsequent carbonization process. The Ni-SA/HPCF with abundant mesopores and an ultrahigh surface area (1137.2 m2 g−1) exhibits unexpected electromagnetic wave (EMW) absorption property with a minimal reflection loss of –53.2 dB and an effective absorption bandwidth of 5.0 GHz, while the filler ratio in the matrix is merely 10 wt.%. Density functional theory calculations and experimental results reveal that the uniformly dispersed Ni-SAs break local symmetry of the electronic structure and increase electrical conductivity of host carbon matrix, thereby enhancing the EMW absorption properties. In addition, the unique 3D hierarchical porous morphology boosts the impedance matching property, which synergistically improves the EMW absorption performance of the Ni-SA/HPCF. This study provides an efficient approach to uniformly disperse M-SAs within hierarchically porous nanocarbons for EMW absorption and other potential applications. 相似文献