Electromagnetic Wave Absorption Research Articles

Construction of enhanced multi-polarization and high performance electromagnetic wave absorption by self-growing ZnFe2O4 on Cu9S5

Construction of enhanced multi-polarization and high performance electromagnetic wave absorption by self-growing ZnFe2O4 on Cu9S5

Multi-interfaced FeCoNi@C/carbon cloth composites for eliminating electromagnetic wave pollution

To tackle the increasing electromagnetic pollution, new and efficient electromagnetic wave absorption (EWA) and shielding (EWS) materials are urgently needed. Multi-component synergism and complex microstructure design are effective measures to improve the EWA and EWS properties. However, how to implement the above designs still faces huge challenges. Herein, multi-interface carbon-coated FeCoNi nanoneedles grown on carbon cloth (FeCoNi@C/CC) were synthesized by a combination of hydrothermal process and chemical vapor deposition (CVD) technology with the concept of “green synthesis”. Using acetylene as the carbon source and atmosphere, the FeCoNi ternary hydroxide can be transformed into a multiple magnetic component (Fe3O4, Ni, and Co metals) by simple annealing. Simultaneously, a uniform carbon layer is formed on the surface, resulting in a composite system with a variety of heterogeneous interfaces and loss mechanisms. Additionally, the dielectric and magnetic loss capacities can be effectively adjusted by changing the temperature of CVD. The optimized FeCoNi@C/CC as filler exhibits remarkable EWA performance with a minimum reflection loss of −69.3 ​dB at a thickness of 1.82 ​mm and a maximum effective absorption bandwidth of 6.80 ​GHz. Moreover, the composites as an integrated component also show a fascinating electromagnetic interference shielding efficiency of 42.2 ​dB. This work provides a guide for the structural design of high-performance electromagnetic protection materials with multi-heterogeneous interfaces.

Tailored Magnetic Spatial Confinement with Enhanced Polarization and Magnetic Response for Electromagnetic Wave Absorption.

For materials with coexisting phases, the transition from a random to an ordered distribution of materials often generates new mechanisms. Although the magnetic confinement effect has improved the electromagnetic (EM) performance, the transition from random to ordered magnetic confinement positions remains a synthetic challenge, and the underlying mechanisms are still unclear. Herein, precise control of magnetic nanoparticles is achieved through a spatial confinement growth strategy, preparing five different modalities of magnetic confined carbon fiber materials, effectively inhibiting magnetic agglomeration. Systematic studies have shown that the magnetic confinement network can refine CoNi NPs size and enhance strong magnetic coupling interactions. Compared to CoNi@HCNFs on the hollow carbon fibers (HCNFs) outer surface, HCNFs@CoNi constructed on the inner surface induce stronger spatial charge polarization relaxation at the interface and exhibit stronger magnetic coupling interactions at the inner surface due to the high-density magnetic coupling units at the micro/nanoscale, thereby respectively enhancing dielectric and magnetic losses. Remarkably, they achieve a minimum reflection loss (RLmin) of -64.54dB and an absorption bandwidth of 5.60GHz at a thickness of 1.77mm. This work reveals the microscale mechanism of magnetic confinement-induced different polarization relaxation and magnetic response, providing a new strategy for designing magnetic materials.

Effect of MXene content on the electromagnetic wave absorption performance of MXene-based composites

Effect of MXene content on the electromagnetic wave absorption performance of MXene-based composites

A novel mullite anti-gyroid/SiC gyroid ceramic metastructure based on digital light processing 3D printing with enhanced electromagnetic wave absorption and mechanical properties

A novel mullite anti-gyroid/SiC gyroid ceramic metastructure based on digital light processing 3D printing with enhanced electromagnetic wave absorption and mechanical properties

Multi-scale design of MWCNT/glass fiber/balsa wood composite multilayer stealth structure with wide broadband absorption and excellent mechanical properties

In unmanned aircraft applications, electromagnetic wave (EMW) absorbers suffer from defects in narrow absorption bands and poor mechanical properties. To solve the problems, a lightweight multilayer stealth structure with wide broadband absorption performance and excellent mechanical properties was designed and prepared by adjusting microscopically the number of multi-walled carbon nanotubes (MWCNT) and modulating macroscopically the thickness-matching relationship of the structure to promote the absorption of EMW synergistically. Under the MWCNT of 30 wt% and the depletion layer with the thickness of 0.2 mm, the effective absorption bandwidth (EAB) covers the entire Ku-band while maintaining a minimum reflection loss (RL) of −15 dB. Besides, the radar cross-sectional area attenuation is as high as 23.1 dBm2, as well as the mechanical properties of the radar absorbing structures (RAS) were improved significantly due to the reducing structural density from balsa wood and the enhancement effect of glass fiber mats (GFM). The study constructed balsa-based RAS with excellent EMW absorbing and mechanical properties from both micro-nano scale and macro-structure, providing a research route for designing high-performance and lightweight stealth structures.

Hydrophobic Alumina Coatings for Magnesium Substrates with Advancing Electromagnetic Wave Absorption Capability

Hydrophobic Alumina Coatings for Magnesium Substrates with Advancing Electromagnetic Wave Absorption Capability

Investigation of the impact of non-magnetic Si element addition and heat treatment on the electromagnetic wave absorption properties of medium entropy FeCoNiSi alloy particles

Based on chemical liquid phase reduction and high temperature annealing, the effects of non-magnetic Si element addition and heat treatment regime on the microstructure, magnetic properties, and electromagnetic wave absorption properties of medium entropy alloy particles FeCoNiSi were studied. The results show that the prepared Fe1Co0.8Ni1Six alloy particles have a spherical structure, and with the increase of Si content, the particle size continuously decreases, with the average particle size decreasing from 150 to 200 nm to 20-50 nm. After high temperature annealing, the alloy particles undergo some agglomeration and growth. The as-prepared Fe1Co0.8Ni1Six alloy particles exhibit an amorphous state, and crystallization occurs during high temperature annealing, but the increase in Si element content has a certain inhibitory effect on the crystallization of the alloy particles. With the increase of Si element content and annealing temperature, the specific saturation magnetization intensity of the material shows a decreasing trend, while the residual magnetism and coercivity show an increasing trend. With the increase of Si element content, the real and imaginary parts of the permeability change alternately in different frequency ranges. The magnetic loss mechanism for the three alloy particles was eddy current loss in the frequency ranges of 10-14GHz and 16.5-18GHz. With the increase of Si element content, the magnetic loss shows an increasing trend, and the impedance matching shows a decreasing trend. The Fe1Co0.8Ni1Si0.5 alloy particle sample has the maximum reflection loss |RLmax| of 28.2 dB at thickness of 2.3 mm, and the Fe1Co0.8Ni1Si0.7 alloy particle sample has an effective absorption bandwidth of 1.7GHz at thickness of 1.9 mm. Eddy current loss was the main magnetic loss mechanism for Fe1Co0.8Ni1Si0.6 alloy particles under 400 °C and 600 °C annealing conditions, and for Fe1Co0.8Ni1Si0.7 alloy particles under 600 °C annealing conditions. With the increase of annealing temperature, the fluctuation of dielectric loss with frequency decreases in the low frequency range, and increases in the high frequency range, while annealing reduces the fluctuation of magnetic loss with frequency. Under 400 °C annealing conditions, the attenuation constant of the three alloy particles was lower than that of the unannealed alloy particles, and under 600 °C annealing conditions, the attenuation constant of Fe1Co0.8Ni1Si0.5 alloy particles in the frequency range of 6-15GHz was higher than that of unannealed and 400 °C annealed alloy particles, and that of Fe1Co0.8Ni1Si0.6 alloy particles in the frequency range of 7-14GHz was higher than that of unannealed and 400 °C annealed alloy particles. High temperature annealing was not able to effectively improve the impedance matching performance of Fe1Co0.8Ni1Six alloy particles. The maximum reflection loss |RLmax| of Fe1Co0.8Ni1Si0.6 alloy particles under 600 °C annealing conditions was 37.8 dB.

Gradient structured MoS2@MXene/MXene/aramid nanofiber composite film with excellent electromagnetic interference shielding performance

Developing high-performance electromagnetic interference (EMI) shielding materials with robust microwave attenuation capabilities and structural stability remains a formidable challenge to enhance their practical adaptability in everyday scenarios. In this study, we have successfully fabricated a gradient structured MXene-based composite film tailored for high-performance EMI shielding. Initially, a hybrid MoS2@MXene material featuring heterointerfaces is synthesized, which exhibits exceptional electromagnetic wave (EMW) absorption capabilities. Subsequently, a gradient structured multi-layer film is engineered using a layer-by-layer casting approach, gradually increasing the MXene content in the MoS2@MXene/MXene/aramid nanofiber composite. This composite film is purposefully designed to employ an “absorb-reflect-reabsorb” EMI shielding mechanism, resulting in reduced reflection power. The resultant composite film achieves an impressive EMI SE of 50.9 dB, coupled with remarkable structural stability persisting through 500 folding cycles. This study presents a viable and potent strategy for developing flexible, absorption-dominant EMI shielding materials.

Serial Nitrogen-Doped Metal/Carbon Composites Derived from Organic Salts for Superior Electromagnetic Wave Absorption and Supercapacitor Electrode.

The present study provides a facile one-pot pyrolysis strategy to prepare serial nitrogen-doped (N-doped) metal/carbon composites derived from six types of metal ethylenediaminetetraacetic acid (EDTA-M, M = Co, Cu, Mn, Fe, Mg, and Ca). N-doped Co/C composite integrated carbonaceous with magnetic components to attain dielectric-magnetic double loss mechanisms. The minimum reflection loss and effective absorption bandwidth reached -57.6 dB at 1.75 mm and 4.64 GHz at 1.52 mm, respectively. The electromagnetic simulation further confirms that the dissipation ability increases with the improvement of carbonization temperature. Results show that altering the metal species of precursors can significantly improve the electrochemical performance of the composites using the identical strategy. N-doped Cu/C composite performed a maximum specific capacitance of 2383.3 F g-1 at 0.5 A g-1 -1, and maintained 86.3% cycling stability at 20 A g-1 after 5000 cycles. The energy density of a symmetrical two-electrode configuration achieved 350.13 Wh kg-1 at a power density of 4000.04 W kg-1. Density functional theory calculations indicate that nitrogen dopants cause faster ion transport and stronger adsorption capacity. Moreover, the bifunctionality of other composites types are also systematically characterized.

A Two-Layer Graphene Nonwoven Fabric for Effective Electromagnetic Interference Shielding.

Rapid advancements and proliferation of electronic devices in the past decades have significantly intensified electromagnetic interference (EMI) issues, driving the demand for more effective shielding materials. Herein, we introduce a novel two-layer graphene nonwoven fabric (2-gNWF) that shows excellent EMI shielding properties. The 2-gNWF fabric comprises a porous fibrous upper layer and a dense conductive film-like lower layer, specifically designed to enhance EMI shielding through the combined mechanisms of reflection, multiple internal reflections, and absorption of electromagnetic waves. The 2-gNWF exhibits a remarkable EMI shielding effectiveness (SE) of 80 dB while maintaining an impressively low density of 0.039 g/cm3, surpassing the performance of many existing graphene-based materials. The excellent EMI shielding performance of 2-gNWF is attributed to the multiple interactions of incident electromagnetic waves with its highly conductive network and porous structure, leading to efficient energy dissipation. The combination of high EMI SE and low density makes 2-gNWF ideal for applications that require lightweight yet effective shielding properties, demonstrating the significant potential for advanced EMI shielding applications.

Multifunctional MXene/rGO aerogels loaded with Co/MnO nanocomposites for enhanced electromagnetic wave absorption, thermal insulation and pressure sensing

Multifunctional MXene/rGO aerogels loaded with Co/MnO nanocomposites for enhanced electromagnetic wave absorption, thermal insulation and pressure sensing

Synergistic Layered Design of Aerogel Nanocomposite of Graphene Nanoribbon/MXene with Tunable Absorption Dominated Electromagnetic Interference Shielding.

Electromagnetic pollution presents growing challenges due to the rapid expansion of portable electronic and communication systems, necessitating lightweight materials with superior shielding capabilities. While prior studies focused on enhancing electromagnetic interference (EMI) shielding effectiveness (SE), less attention is given to absorption-dominant shielding mechanisms, which mitigate secondary pollution. By leveraging material science and engineering design, a layered structure is developed comprising rGOnR/MXene-PDMS nanocomposite and a MXene film, demonstrating exceptional EMI shielding and ultra-high electromagnetic wave absorption. The 3D interconnected network of the nanocomposite, with lower conductivity (10-3-10-2 S/cm), facilitates a tuned impedance matching layer with effective dielectric permittivity, and high attenuation capability through conduction loss, polarization loss at heterogeneous interfaces, and multiple scattering and reflections. Additionally, the higher conductivity MXene layer exhibits superior SE, reflecting passed electromagnetic waves back to the nanocomposite for further attenuation due to a π/2 phase shift between incident and back-surface reflected electromagnetic waves. The synergistic effect of the layered structures markedly enhances total SE to 54.1 dB over the Ku-band at a 2.5 mm thickness. Furthermore, the study investigates the impact of hybridized layered structure on reducing the minimum required thickness to achieve a peak absorption (A) power of 0.88 at a 2.5 mm thickness.

In-Plane heterogeneous Structure-Boosted interfacial polarization in graphene for wide-band and wide-temperature microwave absorption

Theoretically, the strong permittivity dispersion characteristic of materials is essential for achieving broadband electromagnetic wave (EMW) absorption, which can be realized via amplified interfacial polarization effects between a dielectric phase and a lossy phase, such as by increasing the accumulated charge density in their interface area. Herein, we propose a novel strategy to boost interfacial polarization based on heterogeneous structure design in in-plane graphene (Gr) since the in-plane conductivity of Gr is significantly higher than its out-of-plane conductivity. To this end, Gr is grown on Si3N4 nanowires skeleton using chemical vapor deposition (CVD). Subsequently, Gr is controllably etched by Ni nanoparticles, and then, open graphite nanosteps are formed, which help construct in-plane heterogeneous interfaces between Gr and a dielectric phase. Such interfaces also help improve the impedance matching performance by disrupting the long-range conductive network of CVD-grown Gr. Notably, an effective absorption bandwidth of 8.48 GHz is achieved with a thickness of 2.85 mm, which is significantly wider than the EAB (5 GHz) of the out-of-plane heterogeneous structure. In addition, the in-plane heterogeneous structure also endows the EMW absorption material with excellent high-temperature insensitivity, realizing full-frequency absorption in the X-band in the 298–873 K range. This strategy to boost interfacial polarization via novel in-plane heterogeneous structure construction in Gr provides an alternative approach to explore the potential of Gr-based hybrids with planified structures to achieve wide-band and wide-temperature EMW absorption.

Microstructure evolution and excellent electromagnetic wave absorption performance of SiBCN fibers

In this work, SiBCN fibers with excellent electromagnetic wave (EMW) absorption performance were fabricated using electrospinning technology, followed by curing, pyrolysis, and heat treatment. Microstructure evolution and EMW absorption performance of SiBCN fibers after heat treatment at 1200–1600 °C were investigated. After heat treatment at 1200 °C, the conductive turbostratic C was precipitated from amorphous SiBCN fibers, resulting in minimum reflection loss (RLmin) reaching −63 dB and efficient absorption bandwidth (EAB) reaching 5.2 GHz. While turbostratic C and nano-SiC grains were simultaneously precipitated from SiBCN fibers heat treated at 1400 °C, and the RLmin reached −67 dB. The excellent EMW absorption performance of SiBCN fibers was mainly attributed to the synergistic effect of conductive loss, dipole polarization, and interfacial polarization. This work can guide the fabrication of high-performance EMW-absorbing ceramic fibers.

Constructing crystalline/amorphous heterojunction in FeCo@C nanoboxes for enhanced electromagnetic wave absorption

The advanced electromagnetic applications urgently require high performance absorbers with sophisticated structural and compositional design. An effective strategy is to construct a three-dimensional hollow structure, with enhanced electromagnetic wave dissipation capacity over a wide effective absorption bandwidth. However, a major challenge remains due to a single loss mechanism system derived from the conventional hollow nanobox structure, which seriously causes impedance mismatch and lack of polarization centers. Herein, we innovatively construct novel hollow structure FeCo@C (CMFC) with crystalline/amorphous heterojunction FeCo/C particles by cation exchange method, thereby achieving enhanced electromagnetic wave absorption. The CMFC achieves Ku-band effective absorption with a reflection loss of −50.57 dB and effective absorption bandwidth of 5.35 GHz at 1.8 mm. The CMFC exhibits excellent microwave absorption performance due to the presence of crystalline/amorphous FeCo/C heterojunction, which is attributed to the balanced dielectric loss and optimized impedance matching characteristics. CST simulations demonstrate that the CMFC has a radar scattering interface reduction value as high as 26.12 dBm (Wu et al., 2023) [2] at a scattering angle of 0°. This work provides new ideas for the rational design of hollow nanostructures with heterojunction particles for efficient microwave absorption.

SiC whisker/AgNWs/TPU composite film with asymmetric structure for low‐reflection electromagnetic interference shielding

AbstractThe design and preparation of lightweight and flexible electromagnetic interference (EMI) shielding composites with high efficiency and low reflection are critical to the electronic field. First, silver nanowires (AgNWs) were vacuum filtered on the electrospun thermoplastic polyurethane (TPU) fibrous film. Then, by combining the adhesive with the electrospun silicon carbide nanowhisker (SiCnw) @TPU composite fibrous film, the asymmetric EMI shielding composite films with high electromagnetic shielding efficiency (EMI SE) and low incident power were obtained. The lower AgNWs‐TPU layer provides the primary EMI SE, and the upper SiCnw@TPU fibrous film is used for electromagnetic wave absorption. This unique asymmetric structure, the synergistic effect of SiCnw's particular absorbing function and the excellent conductivity of the AgNWs layer make the film show high overall SE (SET = 55.18 dB). In order to improve the absorption effect of the composite film, the number of layers of SiCnw@TPU was adjusted, resulting in a final reflection coefficient value as low as 0.55. This work proposes a new strategy for developing EMI shielding composite films with high efficiency and low reflection, serving as a reference.

Graphene-based tunable broadband metamaterial absorber for terahertz waves

In order to overcome the limitations exhibited by traditional absorbers in electromagnetic wave absorption, such as the extremely narrow absorption bandwidth and uncontrollable absorption results, this paper proposes a novel tunable broadband metamaterial absorber based on graphene. Compared to other terahertz absorbers, the absorber designed in this study exhibits simpler structural design, compact form, thin thickness, efficient absorption performance, and a broader bandwidth. This absorber adopts a three-layer structure, including a patterned monolayer graphene metasurface, a dielectric layer, and a metal substrate. The structure of this patterned graphene consists of four triangular graphene resonators, achieving both high absorption efficiency and maintaining an exceptionally wide absorption bandwidth. The simulation results indicate that at a Fermi energy level Ef of 0.45 eV, the absorber achieves a broadband absorption rate of over 90 % in the 3.287 THz to 5.247 THz frequency range under normal terahertz wave incidence conditions. By analyzing different quantities of the triangular graphene structure on the top of the absorber, we found that the wide absorption bandwidth of the absorber is mainly attributed to the structural coupling of the top-layer graphene in the absorber. Furthermore, through the study of electric field amplitude and current distribution, we stumbled upon that when terahertz waves are incident on the absorber, due to the structural coupling between the graphene layers, electric resonance and magnetic resonance occur within the absorber, resulting in the absorption effect. Finally, through the study of geometric parameters, different polarization angles and oblique incidence angles of the incident waves, as well as different Fermi energy levels of graphene, we discovered that by adjusting the Fermi energy level of graphene, the bandwidth and absorption performance of the absorber can be flexibly tuned. In addition, this absorber exhibits wide-angle absorption characteristics and polarization-insensitive properties, providing potential application prospects in fields such as terahertz thermal imaging and stealth technology.

In situ encapsulation of heterostructures induced microscopic factors to enhance polarization loss of transition metal sulfides microwave absorbers

With the rapid development of modern electronic devices, electromagnetic wave pollution has become increasingly severe. In the field of materials science research, developing superior microwave absorbers holds immense importance. Light-weight carbon nanotube composites are developed for their unique electronic structure and excellent mechanical properties for wide applications in electronics, communication devices, and other specific parts, considering ideal candidates for the preparation of new types of electromagnetic wave absorption materials. This study focuses on embedding Fe7S8/FeS2 heterostructures into nitrogen doped carbon nanotubes through in-situ packaging to optimize interface engineering and improve the electromagnetic wave absorption efficiency of the material. Through pyrolysis and sulfidation processes, we successfully synthesized Fe7S8/FeS2 heterostructures in situ encapsulated within N-doped carbon nanotubes (NCNTs). Fe7S8/FeS2/NCNT shows microwave absorbing ability with a strong absorption (−36.83 dB at 14.08 GHz with a small thickness of 1.6 mm) and a broad effective absorption bandwidth (5.14 GHz). The excellent microwave absorption capability is mainly attributed to the efficient conductive network of NCNTs and the synergistic effect of Fe7S8/FeS2 heterostructures. This not only confirms the potential of transition metal sulfides/NCNTs composites in microwave attenuation applications, but also provides new strategies for the design and development of future microwave absorbers.

A Perspective of Fabrication and Applications of MXene–Metal Hybrids

Abstract2D materials with ultrathin structure, high specific areas, and excellent mechanical properties provide potentials to enhance the electrical, mechanical, and chemical properties of metals. In particular, MXene with different compositions, abundant surface terminations, high electrical conductivity has good affinity with some metals such as Al, Li, Na as well as can be uniformly dispersed in the metals. Moreover, the above unique features enable the MXene–metal hybrids with diversified functions. In this review, the current advanced studies in the topic of MXene–metal hybrids are summarized. The properties of MXenes such as mechanical properties, electrical conductivity, wettability, and surface properties of MXenes are first reviewed. Subsequently, different synthetic approaches including physical, metallurgy, electrochemical, and wet‐chemical routes are screened. By harnessing the above unique features, MXene could enhance the electrical, mechanical, and chemical properties of the hybrids, and their application such as energy storage devices, anticorrosion coating, functional structural materials, electromagnetic wave absorption are highlighted. Finally, an outlook on the in‐operando characterization techniques is provided to clarify the strengthening mechanism of MXenes in metals, tailoration of interface between MXenes and metals, and urgent need for industrial‐scale manufacture of MXene–metal hybrids.