Broadband Electromagnetic Wave Absorption Research Articles

The hollow cubic octahedral structure of Fe3O4 with excellent electromagnetic wave absorption capacity

The unique nanostructure combined with high dielectric and magnetic losses is essential for electromagnetic wave (EMW) attenuation in microwave-absorbing materials (MAM). In this paper, using cubic octahedral Cu2O as a template, we synthesized hollow cubic octahedral Fe(OH)3 at first. After annealing at 450 °C, the hollow cubic octahedral structure Fe3O4 could be obtained. When the filling ratio was 40 %, the minimum reflection loss (RLmin) reached -66.08 dB, and the maximum effective absorption bandwidth (EAB) was 5.38 GHz at a thickness of 1.84 mm, exhibiting improved EMW properties compared with previous works. The hollow cubic octahedral structure of Fe3O4 enhances EMW absorption characteristics, which is attributed to abundant dipole polarization, interface polarization, and good conduction loss. These results indicate that Fe3O4 with the hollow cubic octahedral structure can be used as potential candidates for efficient and broadband EMW absorbers.

Broadband electromagnetic wave absorption properties of RGO cement-based composite

In this study, a cement-based composite was prepared using reduced graphene oxide (RGO) as a raw material via an ethanol liquid-phase mixing pre-dispersion process. The microstructure of cement-based composites with varying RGO contents was discussed, and a systematic investigation was conducted into the electromagnetic wave absorption (EWA) performance of RGO-cement composites within the frequency range of 2–18 GHz. The results indicate that the RGO content significantly impacts its wave absorption performance. Notably, at an RGO content of 3.0 wt%, the wave absorption performance experiences substantial enhancement. For instance, the minimum reflection loss (RLmin) of −48.33 dB at 8.9 GHz with a coating thickness of 2.6 mm is achieved, while an effective absorption bandwidth (EAB) of 5.02 GHz is attained with a thickness of only 1.6 mm, covering nearly the entire Ku-band. The incorporation of high specific surface area RGO into cement materials results in abundant interface polarization losses and additional electromagnetic wave transmission paths, effectively boosting the EWA performance. Consequently, these materials exhibit significant potential for applications in the field of electromagnetic wave shielding.

Construction of 1D heterogeneous PPy@FeCo@PPy nanotubes with broadband and strong electromagnetic wave absorption

Developing nanomaterials with efficient electromagnetic wave absorption to eliminate increasingly serious electromagnetic pollution is of great significance. The peculiar electromagnetic characteristics of one-dimensional dielectric-magnetic heterostructures bring a promising strategy for designing high-efficiency absorber. Herein, a hierarchical PPy@FeCo@PPy nanotube was fabricated through a process of oxidative polymerization and electroless plating. In the product, the FeCo nanoparticles are encapsulate in the middle of the polypyrrole (PPy) dual conductive layers, which facilitates the deep construction of heterointerfaces and simultaneously prevents magnetic agglomeration. Furthermore, the hollow structure and suitable dielectric-magnetic component optimize impedance matching. Profiting from the reasonable structural design and the strong synergistic loss mechanism of dielectric-magnetic, the coaxial multi-shell PPy@FeCo@PPy nanotube exhibits prominent electromagnetic wave absorption performance, with a minimum reflection loss of −50.5 dB and the effective absorption bandwidth of 5.7 GHz at 2.0 mm. This work offers a gentle strategy for preparing ideal microwave absorbers by constructing dielectric-magnetic heterogeneous interfaces.

Ferrite doped sucrose-derived porous carbon composites inspired by Pharaoh's Serpent for broadband electromagnetic wave absorption

This paper presents a straightforward and intriguing approach for designing wide bandwidth, lightweight, and tunable electromagnetic wave (EMW) absorbing materials. Drawing inspiration from the "Pharaoh's Snake", biomass carbon source and sucrose were used to fabricate Fe/Fe3O4@porous carbon (PC) composite materials through combustion experiments. Subsequently, high-temperature calcination was applied to enhance the microwave absorbing properties of the materials. The as-prepared composites demonstrate an impressive 6.62 GHz effective bandwidth and an excellent absorption ability of −51.54 dB at a matched thickness of 2.2 mm. Moreover, by tuning the content of magnetic particles and controlling the thickness of the composite material, comprehensive coverage across C, X, and Ku bands can be achieved. The outstanding performance suggests that the synthesized Fe/Fe3O4@PC porous materials hold significant potential for applications in electromagnetic wave absorption. It opens up a novel, straightforward, and cost-effective approach to acquiring broadband absorbing materials.

Material extrusion 3D printing of large-scale SiC honeycomb metastructure for ultra-broadband and high temperature electromagnetic wave absorption

Electromagnetic (EM) wave absorbing materials have been widely used in various equipment to reduce the interference caused by EM waves. However, current EM wave absorbing materials are limited by narrow absorption bandwidth under high temperatures due to a lack of structural design. Herein, SiC ceramic and large-scale SiC honeycomb metastructure were monolithically fabricated by material extrusion 3D printing. The real permittivity and imaginary permittivity of as-obtained SiC ceramic approached 10 and 2.3 within the frequency of 2–18 GHz. After optimized structure design, the as-obtained SiC honeycomb metastructure exhibited broadband EM performance of −10 dB effective bandwidth from 4.85 to 39.49 GHz (34.64 GHz) when the incident angle was 60° at room temperature. Moreover, the as-obtained SiC honeycomb structure had a stable broadband −10 dB effective bandwidth of above 35 GHz when the incident angle is 60° even after in-situ 1000 °C and ex-situ 1600 °C erosion in the air atmosphere. Broadband EM wave absorption under oblique incident wave was also achieved from 30° to 60° both in transverse electric (TE) polarization and transverse magnetic (TM) polarization. This novel strategy unravels the potential of additive manufacturing of high-performance EM wave absorbers for high temperature environment applications.

Broadband microwave absorption for thin FeSiCr/rGO composites

A series of FeSiCr/reduced graphene oxide composites (FeSiCr/rGO) are successfully prepared by ball milling as a lightweight broadband electromagnetic wave absorbers. The microstructure and absorption properties of the FeSiCr and FeSiCr/rGO composites were compared in detail. The results show that the milled FeSiCr/rGO composite for 1 h can achieve a minimum reflection loss (RLmin) of −15.2 dB at 3.64 GHz with the thickness of 2.0 mm. Whereas, at the thickness of 1 mm, the effective bandwidth is 9.8 GHz when the value of the RL below −5dB. The FeSiCr/rGO composites show better microwave absorption thanks to the improved impedance matching. Furthermore, the peak of RL for FeSiCr/rGO composites, is entirely within the C-band and Ku-band, with a thickness ranging from 1 mm to 2 mm. Overall, this thin and lightweight FeSiCr/rGO composites can meet the requirement of strong and broadband absorber.

Lightweight broadband electromagnetic wave absorption achieved by a like-clustered CNTs spheres modified SiC nanowires

Developing lightweight, broadband, and highly absorptive electromagnetic (EM) wave absorption materials by effectively utilizing the agglomeration effect of one-dimensional nanowires is challenging. In this work, a SiCnws/CNTs aerogel with a like-clustered CNTs sphere-modified SiCnws structure was prepared via simple freeze-drying and heat treatment techniques, where the CNTs content was controlled to adjust the quantity and volume of the CNTs spheres. This allows for effective regulation of the impedance matching characteristics and dielectric loss capability. Specifically, the SiCnws/CNTs aerogel exhibited remarkable dissipation of EM waves through the enhancement of the interface and dipole polarization, achieved by significantly increasing the presence of multiple interfaces and defects. Moreover, the aerogel structure induces conduction loss and amplifies multiple reflections and scattering, facilitating efficient dissipation of EM wave energy across multiple levels. The minimum reflection loss (RLmin) of the SiCnws/CNTs aerogel (SN-3 sample) achieves −43.4 dB at 11.2 GHz with a matching thickness of 2.6 mm. Its effective absorption bandwidth (EAB) spans from the C band to the Ku band (7.4–18 GHz) at thicknesses ranging from 2.1 to 4.4 mm. Additionally, when the matching thickness is 3.4 mm, the broadened EAB extends up to 9.8 GHz (covering the whole X and Ku bands). Furthermore, CST simulations clearly demonstrate a remarkable suppression of the incident EM wave by the samples under real-world conditions, with a substantial reduction of 42.5 dBm2 in the RCS. Considering this, SiCnws/CNTs aerogel materials pave the way for new opportunities in lightweight, broadband, and high-absorption materials.

Symmetric sandwich microcellular (SSM) structure design for multifunctional carbon nanotubes/polymethylmethacrylate composites foam with broadband electromagnetic wave absorption

The ingenious acquisition of lightweight, thin thickness and wide absorption bandwidth electromagnetic wave absorbing (EMWA) materials remains a significant challenge, the architecture design of the absorber is critical. In this study, symmetric sandwich microcellular (SSM) structures made of polymethylmethacrylate (PMMA) and carbon nanotubes (CNTs)/PMMA are developed, and their EMWA behavior is detailed investigated. The optimal effective absorbing bandwidth reaches 3.00 GHz and optimal specific reflection loss value achieves -48.53 dB·g/cm3 over the X-band at 2.5 mm for resulting composite foam with 6 wt.% of CNTs loading, showing a distinct improvement of EMWA performance comparing with normal single-layered sample. The dramatic improved performances mainly ascribe to the better impedance matching and multiple relaxation polarization behaviors derived from SSM structure. Such SSM structure effectively blocks heat conduction, resulting in a lower thermal conductivity (0.092 W/mK), which empowers the material to fulfill dual microwave-infrared stealth meanwhile, it is expected to be a EMWA absorber with the characteristics of “lightweight, multifunction and comprehensiveness”.

Strong Magnetic–Dielectric Synergistic Gradient Metamaterials for Boosting Superior Multispectral Ultra‐Broadband Absorption with Low‐Frequency Compatibility

AbstractThe construction of 3D porous structures and metamaterials (MMs) is the most promising approaches to achieve broadband electromagnetic wave (EMW) absorption. However, it is still a huge challenge to achieve multispectral ultra‐broadband EMW absorption properties compatible with low‐frequency band (L‐ and S‐band) due to its ultralong wavelength and strong bypass capability. Herein, magnetic–dielectric synergistic gradient MMs (MDSGM) consisting of oriented flaky carbonyl iron (FCI) film and periodical RGO/CNT/CNF aerogel (GTFA) array are demonstrated. Benefiting from the synergistic effect of strong magnetic–dielectric loss, structural loss, and excellent impedance matching, MDSGM harvests an exciting multispectral ultra‐broadband EMW absorption performance with a remarkable effective absorption bandwidth covering the whole measured frequency of 1–40, 50–110 GHz, and 0.1–2.0 THz for the first time. The minimum RL (RLmin) reaches −40.24 dB and average RL is up to −19.3 dB (98.8% EMW being absorbed) in microwave band. Moreover, this multispectral ultra‐broadband EMW absorption property is less affected by the incident angle. This work pioneered realization of multispectral ultra‐broadband EMW absorption compatible with low‐frequency, which provides a great thrust for the development of stealth technology in the upcoming smart era.

A simple co-doping strategy to synthesis of Ni@B/N carbon nanotubes with broadband and low-frequency electromagnetic wave absorption

Development of magnetic composites with rational microstructural design to achieve excellent electromagnetic wave (EMW) absorption in the low-frequency range is necessary and still challenging. Herein, the B/N carbon nanotubes loaded with Ni nanoparticles were successfully synthesized through a homogeneous precursor pyrolysis route. The homogeneity of the micro-magnetic field in the composite architecture is improved by the co-doping of B and N in carbon nanotubes due to the polarization effect, which would enhance the impedance matching and EMW absorption. The Ni@B/N carbon nanotubes exhibit a minimum reflection loss (RLmin) of −56.9 dB at 8.24 GHz with a maximum bandwidth of 7.12 GHz ranging almost all S and C bands (from 3.44 to 10.56 GHz) suggesting that the composite architecture effectively enhances low-frequency EMW absorption properties. The combination of impedance matching and interfacial polarization resulting from the homogeneous Ni nanoparticles and co-doping of B and N in carbon lattice structure is responsible for the enhanced low-frequency EMW absorption properties. This simple co-doping synthesis strategy provides a new design strategy for the preparation of broadband and low-frequency EMW absorbers.

Mechanical metamaterials as broadband electromagnetic wave absorbers: investigating relationships between geometrical parameters and electromagnetic response.

The utilization of low-density and robust mechanical metamaterials rises as a promising solution for multifunctional electromagnetic wave absorbers due to their structured porous structures, which facilitates impedance matching and structural absorption. However, the various geometrical parameters involved in constructing these metamaterials affect their electromagnetic response, necessitating a comprehensive understanding of underlying absorbing mechanisms. Through experimentally validated numerical analysis, this study delves into the influence of geometrical factors on the electromagnetic response of representative low-density, high strength mechanical metamaterials, namely octet-truss and octet-foam. By juxtaposing electromagnetic response under varying volume fractions, cell lengths, and multilayer configurations of octet-truss and octet-foam, distinct absorption mechanisms emerge as geometrical parameters evolve. These mechanisms encompass diminished reflection owing to porous structures, effective medium approximations within subwavelength limits, and transmission-driven or reflection-driven phenomena originating from the interplay of open- and closed-cell structures. Through analyses on these mechanical metamaterials, we demonstrate the viability of employing them as tunable yet scalable structures that are lightweight, robust, and broadband electromagnetic wave absorption.

Robust and flexible composite aerogel films with porous multilayered structures toward broadband electromagnetic wave absorption

Robust composite aerogel films exhibit superior electromagnetic wave absorption performance, owing to multilayered heterostructures assisted by MXene and Ni nanochains.

Preparation of CIP@TiO2 composite with broadband electromagnetic wave absorption properties

Preparation of CIP@TiO2 composite with broadband electromagnetic wave absorption properties

3D-printed stepped structure based on graphene-FeSiAl composites for broadband and wide-angle electromagnetic wave absorption

The design and preparation of absorbers with ultra-wide bandwidth and wide-angle absorption characteristics are crucial technologies for addressing electromagnetic (EM) pollution. In this paper, a stepped structure absorber was fabricated of graphene (GR)-FeSiAl/polylactic acid (PLA) composite by 3D printing technology. The absorber contains four layers, the bottom layer being a slab with periodic square holes, and the upper layer is a periodic distribution of three cubes with equal thickness and gradient changes in side length. It is shown that the stepped structure achieves a minimum reflection loss (RLmin) of −36.01 dB, with an effective absorption bandwidth (EAB, corresponding to the bandwidth of RL < −10 dB) of 12.75 GHz. These results were obtained when the unit cell had a side length of 22.5 mm, the slab thickness was 1.5 mm, and the cube had a thickness and edge length difference of 2.5 mm and 4.0 mm, respectively. Furthermore, the value of EAB is greater than 10 GHz for both transverse electric (TE) polarization and transverse magnetic (TM) polarization when the incident angle changes from 0° to 50°. The broadband and efficient EM wave (EMW) absorption characteristics of this absorber can be attributed to integration of excellent impedance matching and the multi-scale loss mechanisms.

Achieving broadband electromagnetic absorption at a wide temperature range up to 1273 K by metamaterial design on polymer-derived SiC-BN@CNT ceramic composites

High-temperature broadband electromagnetic wave (EMW) absorption has emerged as a forefront challenge of EMW functional materials for harsh environment applications such as aerodynamically heated parts of stealth aircraft and aero engines. Herein, an innovative strategy for broadband absorption at high temperatures is proposed by combining the microstructural design of the EMW absorption phase in the polymer-derived SiC with a periodic structure design. The metamaterial was designed on SiC-BN@CNT ceramic composites with the shape of a frustum pyramid. The experimental results reveal that SiC-BN@CNT metamaterials exhibit excellent absorption performance even under a high-temperature environment of 1273 K, in which the effective absorption bandwidth (EAB) (below −10 dB) can achieve 15.52 GHz, almost covering the whole S, C, X, and Ku bands. Moreover, the CST simulation results show that the SiC-BN@CNT metamaterials have an impressive EAB of 34.62 GHz and the average absorption intensity is remarkably high with a value of 21.07 dB (<99 % absorption) in the frequency range of 2–40 GHz. The exciting EMW attenuation capability is ascribed to favorable impedance matching, enhanced conduction loss abilities, and multiple polarization loss at high temperatures. This work provides valuable insights for the development of broadband-absorbing material in high-temperature harsh environments.

Broadband electromagnetic wave absorption performance of CuS-biomass carbon composites derived from moss

The absorption performance of broadband electromagnetic waves is of utmost importance in safeguarding diverse electronic equipment against electromagnetic wave pollution, necessitating materials with low density, thin thickness, and cost-effectiveness to be employed. This study presents the successful synthesis of biomass-derived carbon (BC) composites via the hydrothermal method, utilizing moss coated with flower-like CuS. The CuS was uniformly dispersed on BC matrix, contribute to dipole polarization relaxation. The formation of heterogeneous interfaces between CuS and the BC phase resulted in significant polarization loss. Additionally, the wrinkled BC and flower like CuS constructed by nanosheets boosted scattering of electromagnetic wave due to its large specific surface area, which can provide additional channels for charge transfer and avail dissipation of electromagnetic wave energy. With an efficient absorption bandwidth (EAB) that encompasses the whole X band, the electromagnetic waves absorption (EMA) performance of CuS/BC composites was able to reach a minimum reflection loss of − 28.8 dB.

Carbonization of Ni@SiC@C nanoparticles reinforced PAN nanofibers for adjustable impedance matching

Achieving a broad bandwidth and efficient absorption of electromagnetic wave absorption materials remains a significant challenge, especially when considering electromagnetic pollution protection. One-dimensional carbon nanofibers with a three-dimensional network structure have been extensively studied to address this need. However, the high permittivity of carbon nanofibers results in a strong impedance mismatch with free space. In this work, we successfully dispersed double-shell Ni@SiC@C nanoparticles into one-dimensional carbon nanofibers (Ni@SiC@C CNFs) using electrospinning and heat treatment. We extensively explored the effect of carbonization temperature on the impedance matching and magnetic-dielectric loss for electromagnetic wave. The presence of rich interfaces from the double-shell nanoparticles and defects from N-doping optimizes the impedance matching of the composites. The exceptional electromagnetic wave absorption properties of the Ni@SiC@C CNFs are attributed to the synergistic effect between the three-dimensional conductive network, the interface electronic engineering induced by the sensibly loaded double-shell nanoparticles, and the multiple reflections, especially at a carbonization temperature of 600 ℃. The achieved minimum reflection loss value has been measured at an outstanding −53.27 dB, coupled with a remarkable absorption bandwidth that spans from 2.53 GHz to 18.00 GHz (15.47 GHz) across various thicknesses. These findings underscore the potential of the meticulously engineered Ni@SiC@C CNFs as highly promising candidates for efficient and broadband electromagnetic wave absorption applications.

MOFs derived multi-scale lamellar network for broadband electromagnetic wave absorber

Developing an efficient EM wave absorbing material that can broadband absorb EM waves in a wide thickness range is a significant challenge. Herein, we report a multi-scale heterogeneous Co/C composite foam with a three-dimensional (3D) lamellar network to address this challenge. The internal structure of melamine foam (MF) is engineered via carboxymethyl cellulose (CMC) in-situ lamella formation to guarantee excellent impedance matching. Meanwhile, the CMC lamellar network extends the EM wave transmission path. The MOF-derived particles grow uniformly in the lamellar network, covering channels of EM wave transmission, which significantly enriches the EM wave loss mechanism and enhances attenuation capability. Benefiting from the synergistic effect of the 3D lamellar network and multi-scale heterogeneous carbon source, an EM absorber strikes a balance between impedance matching and absorption efficiency. As a result, Co/C@MC delivers an effective absorption bandwidth (EAB) that is more than 8 GHz in the whole range of thicknesses from 3.5 to 8 mm, Ni/C@MC exhibits an EAB of 8.5 GHz at 3.3 mm and Fe/C@MC shows the optimal reflection loss of −76.9 dB at 2.5 mm. This work provides a lamellar network/regional enhancement unit strategy for preparing ultra-efficient broadband EM wave absorbing materials.

3D printed composites achieve broadband electromagnetic wave absorption by introducing carbon black/carbonyl iron powder porous hollow microspheres

In this paper, carbon black (CB) and carbonyl iron powder (CIP) were successfully combined by solvent evaporation method to prepare CB-CIP porous hollow microspheres and used as reinforcement to prepare electromagnetic wave absorbing composites by 3D printing method. The effects of CB addition on the structure of the composite microspheres and the wave absorption performance were investigated. It is shown that the surfaces of hollow microspheres have many heterogeneous interfaces and pore defects, which can significantly enhance the polarization loss capability. The CB and CIP particles on the surfaces of hollow microspheres are intertwined, which makes the magnetic loss and dielectric loss form a synergistic absorption effect and enhance the microwave absorption capacity of the composite. The maximum reflection loss of sample CB/PLA-3 reaches –47.34 dB at a thickness of 2.5 mm, and the EAB is 4.56 GHz. The EAB reaches a maximum of 5.20 GHz at a thickness of 2 mm. The RCS simulation results of CB/PLA-3 at 11 GHz show that most of the RCS values of the samples are below −20 dBm2 in the range of –90° < Theta < 90°, indicating that the CB/PLA-3 samples has the capability of wide-angle microwave absorption. This paper provides an effective method for the design and preparation of broadband efficient absorbing materials.

Ultra-broadband and wide-angle microwave absorber based on resistive films with a 3D configuration

This paper introduces a broadband electromagnetic wave absorber with characteristics of polarization-independence and wide-angle stability based on resistive films with a three-dimensional (3D) configuration. The absorber consists of a 3D dielectric substrate array covered by a resistive film, which not only broadens the operation frequency band but also improves the absorption with large incidence angles. Simulated results indicate that the absorber achieves wideband absorption with over 90% absorptivity in the frequency range of 5.7–41.8[Formula: see text]GHz, corresponding to a relative absorption bandwidth of 152%. Due to the high symmetry of the structure, the absorber is insensitive to polarization angles. Moreover, the presented design maintains wave absorption greater than 90% when incidence angle reaches 70∘ due to its 3D structure that ensures high absorption for wide incidence angles. The mechanism of this structure is investigated through surface current and power consumption distribution, while optimization parameters are analyzed for achieving the desired bandwidth. This absorber has the advantages of wide-band absorption and excellent stability under oblique incidence angles, making it potentially useful in applications such as electromagnetic shielding and energy harvesting.