Electromagnetic Absorption Performance Research Articles

SiC particles/Ti3C2Tx aerogel with tunable electromagnetic absorption performance in Ku band

In response to the issues stemming from electromagnetic wave (EMW) radiation or pollution, there has been a growing emphasis on the research and development of novel electromagnetic wave absorbing materials. In this work, we synthesized an EMW absorbing aerogel composed of SiC particles and Ti3C2Tx, with the structure regulated by PVA. The aerogel features a well-organized 3D network comprising Ti3C2Tx nanosheets (NSs), SiC particles, and PVA wires. At a mass ratio of 1:1 for SiC particles to Ti3C2Tx, the aerogel, when combined with PVA, demonstrated a remarkable reflection loss of -54.5 dB in the Ku band and an effective absorption bandwidth (EAB) of 5.4 GHz at a thickness of 2.04 mm. Even at low densities of 8.8 mg cm−3, the aerogel demonstrated significant mechanical strength, supporting a load equivalent to 1000 times its weight. The superior absorption capabilities of the SiC particles/Ti3C2Tx aerogel can be ascribed to the multiple interface polarization between Ti3C2Tx and SiC particles, and the impedance matching improved by the presence of PVA. These findings underscore the exceptional EMW absorption properties of the SiC particles/Ti3C2Tx aerogel, particularly in the Ku band.

Enhancing electromagnetic properties in nickel hydroxide modified graphene composites via secondary reactions for improving multi-polarization electromagnetic absorption efficiency

Carbon-based materials exhibit excellent dielectric absorption properties, among which graphene has received particular attention in research of electromagnetic wave absorbing materials because of its high electrical conductivity and unique large-area, thin-layer two-dimensional structural features. However, the electromagnetic absorption performance of the material is hindered from further improvement due to its single component composition. It is influenced by the conductive network of graphene, making it challenging to achieve a balance in impedance matching and electromagnetic loss, thereby restricting its broader application. To address these challenges, we developed a series of nickel hydroxide-modified graphene composites. Through a structural composite design, we optimized overall impedance matching, introduced diverse loss mechanisms to enhance electromagnetic loss performance, and utilized a secondary reaction control method to precisely regulate the deposition of nickel hydroxide on the graphene surface, thereby achieving regulate of the composite material's electromagnetic parameters within a defined range. Under low sample filling ratios and a thin sample thickness of 1.8 mm, the effective absorption bandwidth reaches 6.5 GHz, demonstrating excellent electromagnetic absorption performance. This study provides a controllable design approach for modulating material electromagnetic parameters by influencing the reaction process. It also offers a design method for composites with an outstanding electromagnetic loss mechanism.

Preparation and electromagnetic waves absorption performance of hibiscus-like CuS/SiC NWs@PANI in the GHz band

With the increasing demand for electromagnetic (EM) waves absorbing materials in communication, military, and electronic devices, the exploration of lightweight, wideband, and highly absorptive materials in the GHz frequency range has become urgent. This article presents a successful synthesis of hibiscus-like copper sulfide (CuS)/silicon carbide nanowires (SiC NWs) @polyaniline (PANI) composite material using a combination of hydrothermal and in-situ polymerization techniques. With a filling amount of only 25 wt% of CuS/SiC NWs@PANI in the paraffin transmissive matrix, the material exhibits a minimum reflection loss (RLmin) of −31.6 dB at a thickness of 2.1 mm, while providing an effective absorption bandwidth (EAB) of 4.5 GHz. As the filling amount increases to 35 wt%, the RLmin drastically reduces to −41.38 dB at a thickness of 2.3 mm. The CuS particles exhibit a unique multi-layered asymmetric hibiscus-like structure, which greatly enhances the reflection of EM waves. The conductive polymer PANI, forming a coating layer at the interface with CuS and SiC NWs, effectively enhances the conductive loss. The collaborative interactions among the components in the ternary composite material significantly boost the EM waves absorption performance. This article offers valuable insights into the preparation and real-world application of absorbent materials with distinctive microstructures, thus opening up new avenues for the design of composite absorbing materials.

Heterointerface engineering in porous microspheres for magnetic-dielectric balance to boost electromagnetic wave absorption

Heterointerface engineering originated from structure design is a promising approach to develop high-performance electromagnetic (EM) absorption materials but remains challenges in revealing the EM modulation mechanism. In this work, a diffusion-driven self-assemble strategy was proposed to construct porous NiFe2O4 microspheres with rich confined cavities. Followed by an in-situ vapor phase polymerization, conductive polypyrrole (PPy) layers were tightly coated on NiFe2O4 surface, building numerous ferrite-polymer heterointerfaces. Systematic investigation demonstrated that the controllable coating thickness and porous structure were crucial to regulate the component dependency EM properties and the dielectric-magnetic balance. Accordingly, these activated heterointerfaces and lattice defects inevitably produced polarization response to enhance the dielectric loss, and the confined magnetic coupling among hierarchical cavities strengthened the magnetic loss, jointly contributing to the boosted dissipation of incident EM energy. Owing to the synergy merits, optimum core–shell NiFe2O4@PPy microspheres exhibited an impressive broadband EM absorption performance with a wide effective absorption bandwidth covered 6.8 GHz at 2.62 mm. This study provides methodological guidance to design magnetic-dielectric EM absorption materials, and deciphers the mechanism of structure-interface modulated EM properties.

Multilevel Heterogeneous Interfaces Enhanced Polarization Loss of 3D-Printed Graphene/NiCoO2/Selenides Aerogels for Boosting Electromagnetic Energy Dissipation.

Heterointerface engineering is an attractive approach to modulating electromagnetic (EM) parameters and EM wave absorption performance. However, the weak interfacial interactions and poor impedance matching would lead to unsatisfactory EM absorption performance due to the limitation of the construction materials and design strategies. Herein, multilevel heterointerface engineering is proposed by in situ growing nanosheet-like NiCoO2 and selenides with abundant interface structures on 3D-printed graphene aerogel (GA) skeletons, which strengthens the interfacial effect and improves the dielectric polarization loss. Benefiting from the features of substantially enhanced polarization loss and optimized impedance matching, the graphene/S-NiCoO2/selenides (G/S-NCO/Se) have achieved brilliant EM wave absorption performance with a strong reflection loss (RL) value of -60.7 dB and a broad effective absorption bandwidth (EAB) of 8 GHz, which is about six times greater than that of the graphene aerogel (-9.8 dB). Moreover, it is further confirmed by charge density differences and off-axis electron holography that a large amount of polarized charge accumulates at the interface, leading to significant polarization relaxation behaviors. This work provides a deep understanding of the effect of a multilevel heterogeneous interface on dielectric polarization loss, which injects a fresh and infinite vitality for designing high-efficiency EM wave absorbers.

Thermal Management by Manipulating Electromagnetic Parameters

Abstract Electromagnetic absorbing materials may convert electromagnetic energy into heat energy and dissipate it. However, in high-power electromagnetic radiation environment, the temperature of the absorbing material rises significantly and even burns. It becomes critical to ensure electromagnetic absorption performance while minimizing temperature rise. Here, we systematically study the coupling mechanism between the electromagnetic field and the temperature field when the absorbing material is irradiated by electromagnetic waves. We find out the influence of the constitutive parameters of the absorbing materials (including uniform and non-uniform) on the temperature distribution. Finally, through a smart design, we achieve better absorption and lower temperature simultaneously. The accuracy of the model is affirmed as simulation results aligned with theoretical analysis. This work provides a new avenue to control the temperature distribution of absorbing materials.

Rare earth Ce-doped W-type barium ferrites for tunable electromagnetic waves absorption performance

W-type ferrites possessing low cost and high chemical stability, show high potential in electromagnetic wave (EMW) absorption field. However, due to the low dielectric loss, developing high EMW absorption performance of W-type ferrites remains desired. Here, rare earth (RE) cerium (Ce)-doped W-type barium ferrites (Ba1-yCeyNi2Fe15.4O27, y = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) are prepared by a sol-gel approach. The influences of Ce doping are detailed analyzed. Ce ions with unpaired 4f electrons and strong spin-orbit coupling of angular momentum enhance the dielectric and magnetic properties of ferrites. Ba0.7Ce0.3Ni2Fe15.4O27 achieves the minimum reflection loss (RLmin) value of -52 dB while Ba0.6Ce0.4Ni2Fe15.4O27 showcases the widest effective absorption bandwidth (EAB) of 1.36 GHz associated with the RLmin reaching -38 dB, significantly outperforming the undoped ferrites. This work thus demonstrates a high-efficiency utilization of Ce for enhancing the EMW absorption performance of widely employed W-type barium ferrites, efficiently advancing the application field of RE elements.

A radar-infrared compatible stealth metamaterial with bird's nest morphology

The rapid development of detection technology, the technology with radar infrared compatible stealth function has become one of the important ways to improve the survivability of weapons and equipment. However, the two stealth mechanisms of radar stealth and infrared stealth are mutually exclusive. In this work, a multilayer radar-infrared compatible stealth metamaterial is presented based on SiO2 fiber reinforced aerogels skeleton (SFRAS). The prepared samples with bird 's nest microstructure showed good compressive strength (1.73–2.52 MPa) and low density (0.22–0.27 g/cm3), achieving lightweight. Moreover, the metamaterial exhibits excellent electromagnetic absorption performance, effective absorbing broadband (13 GHz), and ultra-wideband absorption of electromagnetic waves is achieved. Nanoporous structure and low thermal conductivity (0.03426–0.05011 W/ (m K)) successfully reduce the surface thermal radiation, indicating that it is a potential material for achieving infrared stealth. The new technology provides a new approach to the research of the radar-infrared compatible stealth structure.

Magnetically engineering enhanced EMA property through high entropy transition metal ions within all-inorganic perovskite

Addressing challenges such as signal interference and crosstalk requires the development of new materials capable of electromagnetic absorption (EMA). In this study, we explored magnetically high-entropy engineering by incorporating transition metal ions into the B sites of all-inorganic CsPbBr3 perovskite. This approach yielded excellent EMA properties, including a minimum reflection loss of 75 dB at 10.2 GHz with a thickness of 2.5 mm and an effective bandwidth of 8.8 GHz. Fe, Co, Ni, and Mn ions were successfully introduced into the CsPbBr3 lattice using high-energy ball milling and the combustion method. Through rigorous characterization techniques such as Rietveld refinement of X-ray diffraction and Grazing-Incidence Wide-Angle Scattering patterns, we confirmed the presence of high-entropy phases. Additionally, we conducted comprehensive studies using Vibrating-sample magnetometer, L2,3 edge XANES, and Mossbauer spectra to investigate the magnetic polarization, spin states, and dipolar exchanges of the transition metal ions. The observed synergistic effects among the magnetic permeability, polarization, and magnetic loss of these ions underscored their role in enhancing the EMA performance of CsPbBr3.

Hollow spherical SiC@Ni composites towards the tunable wideband electromagnetic wave absorption

Combining dielectric substrates and magnetic materials is a practical approach to improve electromagnetic wave (EMW) absorption performance due to the dielectric and magnetic synergy loss effect. In this work, uniform monodisperse hollow SiC@Ni (H–SiC@Ni) composites were synthesised through a simple route, including the sacrificial templating method and the subsequent reduction reaction. Different contents of Ni3S2 and Ni could be obtained by adjusting the volume and reaction temperature, which are closely related to the electromagnetic parameters and absorption capabilities. The results show that the H–SiC@Ni-750 composite reaches the optimum EMW absorption performance with the minimum reflection loss of −55.7 dB at 7.3 GHz and the effective absorption bandwidth (EAB) of 8.8 GHz at 2.6 mm. The high absorption performance of the H–SiC@Ni-750 composite benefits from the synergistic dielectric loss and magnetic loss of SiC and Ni nanoparticles. In addition, the hollow and monodisperse core-shell structure of the samples can increase the transmission path through multiple reflections and scattering and further dissipate the EMW energy. This work provides a facile pathway to prepare H–SiC@Ni composite with broadband electromagnetic absorption performance.

Polyaniline-mediated hydrophobic modification of carbonyl iron powder (CIP) as durable and efficient electromagnetic absorbents with good corrosion resistance

Carbonyl iron powder (CIP) is a widely used and commercially available functional material, but the susceptibility to electrochemical corrosion limits its application in humid and salty environments. In this study, a novel surface modification strategy that grafts stearoyl chloride on CIP with polyaniline (PANI) as the medium is developed to strengthen its anticorrosion performance. Modified CIP shows strong hydrophobicity and the static water contact angle can reach up to 141°. This surface modification increases the corrosion potential from −0.75 to −0.32 V and decreases the corrosion current from 6.3×10−6 to 5.0 × 10−7 A/cm2. After immersing in acidic NaCl solution for 240 h, modified CIP still exhibits powerful electromagnetic (EM) absorption performance, including strong reflection loss and broad absorption bandwidth, very close to that of pristine CIP. In contrast, CIP without surface modification presents a drastic reduction in EM function, especially reflected in narrow absorption bandwidth and increased matching thickness.

Constructing three-dimensional wool-spherical vanadium-doped Nb2O5 microspheres with superior electromagnetic absorption performance

Three-dimensional (3D) wool-spherical Nb2O5/V microspheres were successfully manufactured via an ultrasonic spray method, aiming to attain an optimal electromagnetic wave absorption (EWA). The introduction of the V element through doping tunes the conductivity of the Nb2O5 microspheres and promotes the formation of multiple heterogeneous interfaces, leading to enhanced polarization and conductive losses. Additionally, the formation of a 3D architecture not only promotes structural stability but also extends the pathways of the reflected and scattered electromagnetic waves (EWs), leading to a greater consumption of EW energy. Due to their good impedance matching properties and attenuation capabilities, Nb2O5/V exhibited remarkable EWA performance with a minimum reflection loss of −47.52 dB and an effective absorption bandwidth of 2.5 GHz at a thickness of 2.25 mm in the X band. This study provides a valuable reference for guiding the design of high-performance Nb2O5-based absorber materials.

Achieving Superior Electromagnetic-Absorbing Performances in the Hexagonal Flake BaFe12O19@PVDF Composites.

Combining magnetic and dielectric materials to form a composite can significantly improve its impedance matching and electromagnetic wave absorption performance. Furthermore, composite materials with a core-shell structure hold promise in meeting the demand for lightweight and highly electromagnetic-absorbing properties. In this study, uniform hexagonal flake barium ferrite (BaFe12O19) was prepared using the hydrothermal method. Subsequently, BaFe12O19@PVDF composites were synthesized by the sol-gel method. By adjusting the mass ratio of BaFe12O19 and PVDF, the shell size of the BaFe12O19@PVDF composite material was controlled, and its electromagnetic absorption performance was enhanced. The shell thickness of BaFe12O19@PVDF is 19.64 nm when the BaFe12O19: PVDF mass ratio is 1:1.0, and the optimal impedance matching is obtained at 13.4 GHz. Meanwhile, at a thickness of 1.5 mm, the minimum reflection loss (RLmin) reached -58.04 dB, and an effective absorption bandwidth (EAB) (RL ≤ -10 dB) of 5.53 GHz was achieved within the frequency range of 11.65 to 15.63 GHz and from 16.36 to 17.91 GHz. Besides, the composites with a matching thickness of 3.5 mm show a maximum EAB of 15.90 GHz when the mass ratio of BaFe12O19 to PVDF is 1:1.2. Within the frequency range of 2-18 GHz, the coverage of reflection loss less than -10 dB is 99.38%, almost achieving full coverage. These results demonstrate that BaFe12O19@PVDF composites exhibit excellent electromagnetic-absorbing performances, making them an excellent candidate for electromagnetic wave absorption in 5G communications.

Large Microsphere Structure of a Co/C Composite Derived from Co-MOF with Excellent Wideband Electromagnetic Microwave Absorption Performance.

In the field of electromagnetic wave (EMW) absorption, carbon matrix materials based on metal-organic frameworks (MOFs) have drawn more interest as a result of their outstanding advantages, such as porous structure, lightweight, controlled morphology, etc. However, how to broaden the effective absorption bandwidth [EAB; reflection loss (RL) ≤ -10 dB] is still a challenge. In this paper, large microsphere structures of a Co/C composite composed of small particle clusters were successfully prepared by the solvothermal method and annealing treatment. At a filling ratio of 40 wt %, the Co/C composite shows attractive microwave absorption (MA) performance after being annealed at 600 °C in an atmosphere of argon. With an EAB of 6.32 GHz (9.92-16.24 GHz) and a thickness of just 2.57 mm, the minimum RL can be attained at -54.55 dB. Most importantly, the EAB can attain 7.12 GHz (10.88-18.0 GHz) when the thickness is 2.38 mm, which is larger than that of the majority of MOF-derived composites. The superior MA performance is strongly related to excellent impedance matching and a higher attenuation constant. This study provides a simple strategy for synthesizing a MOF-derived Co/C composite with a wide EAB.

MnFe2O4/polyaniline/diatomite composite with multiple loss mechanisms towards broadband absorption.

The research and development of absorbing materials with high absorbing capacity, wide effective absorption bandwidth, and lightweight has always been interesting. In this research, a facile hydrothermal method was used to prepare MnFe2O4, and the grain size of MnFe2O4 decreased with increasing hydrothermal temperature. When the size of MnFe2O4 nanoparticles is less than 10nm, its quantum size effect and surface effect make its electromagnetic microwave absorption performance greatly optimized. When the thickness of MnFe2O4-110 °C is 2.57mm, the minimum reflection loss (RLmin) is -35.28 dB. Based on this, light porous diatomite and a three-dimensional polyaniline network are introduced. Diatomite is used as the base material to effectively reduce the agglomeration of MnFe2O4 quantum dots. The relatively high surface area introduced by a three-dimensional network of polyaniline promotes the orientation, interfacial polarization, multiple relaxation, and impedance matching, thereby generating further dielectric loss. Additionally, the magnetic properties of manganese ferrite and the strong electrical conductivity of polyaniline play an appropriate complementary role in electromagnetic wave absorption. The RLmin of MnFe2O4/PANI/diatomite is -56.70 dB at 11.12GHz with an absorber layer thickness of 2.57mm. The effective frequency bandwidth (RL < -10 dB) ranges from 9.21 to 18.00GHz. The absorption mechanism indicates that the high absorption intensity is the result of the synergistic effect of impedance matching, conduction losses, polarization losses, and magnetic losses.

Engineering Phase to Reinforce Dielectric Polarization in Nickel Sulfide Heterostructure for Electromagnetic Wave Absorption.

Engineering phase transition in micro-nanomaterials to optimize the dielectric properties and further enhance the electromagnetic microwave absorption (EMA) performance is highly desirable. However, the severe synthesis conditions restrict the design of EMA materials featuring controllable phases, which hinders the tunability of effective absorption bandwidth (EAB) and leads to an unclear loss mechanism. Herein, a seed phase decomposition-controlled strategy is proposed to induct nickel sulfide (NiSx ) absorbers with controllable phases and hollow sphere nature. Transmission electron microscopy holography and theoretical calculations evidence that the reconstruction of atoms in phase transition induces numerous heterogeneous interfaces and lattice defects/sulfur vacancies to cause varied work functions and local electronic redistribution, which contributes to reinforced dielectric polarization. As a result, the optimized NiS2 /NiS heterostructure enables enhanced EM attenuation capability with a wide EAB of 5.04GHz at only 1.6mm, compared to that of NiS2 and NiS. Moreover, the correlation between EAB and NiS phase content is demonstrated as the "volcano" feature. This study on the concept of phase transition of micro-nanomaterials can offer a novel approach to constructing highly efficient absorbers for EMA and other functionalities.

Assembly of Multi-Dimensional Microstructures of MXene towards Wearable Electromagnetic Attenuating Devices

MXene is a competitive and attractive 2D material used in wearable electromagnetic devices due to its laminated nanostructure, abundant surface terminations and high conductivity. Assembling MXene nanosheets into multi-dimensional microstructures is considered to be an effective method for improving the overall performance of MXene-based composites, especially their electromagnetic attenuation and wearability performance. This article focuses on the strategies for assembling multi-dimensional MXene microstructures, from 0D spheres and 1D fibers to 2D films and 3D architectures. The origin of the electromagnetic response of MXene microstructures is revealed, and the corresponding electromagnetic absorption and interference shielding performance are shown. Furthermore, additional extended functions that serve wearable electromagnetic attenuation devices are highlighted. Finally, the application prospects and challenges of wearable electromagnetic devices, as well as the function integration of multi-dimensional MXene composites, are summarized.

Nanodiamond@hollow carbon sphere architectures for synergistically enhanced electromagnetic absorption and thermal insulation

Carbon materials stood out for electromagnetic absorption due to the lightweight, high-stability and well designability. At present, the research bottleneck lied in achieving broadband absorption and versatility. Novel nanodiamond@hollow carbon sphere architectures were designed in this work, involved with all‑carbon hollow structures and the multiple heterophase interfaces. Bifunctional improvement was realized through the all‑carbon architectures design. Superior electromagnetic wave absorption performance was obtained at an extremely low loading ratio of 5 wt% of the nanodiamond@hollow carbon sphere architectures. With a thickness of 2.15 mm, the optimal reflection loss peak could be −47.1 dB, and the specific absorbing value achieved 438 dBmm−1. Meanwhile, the nanodiamond@hollow carbon sphere architectures exhibited significantly improved thermal insulation characteristics. The simultaneously enhanced electromagnetic absorption and thermal insulation performances were proved to be benefited from the multiple CN hybridizations and the novel all‑carbon hollow hierarchical structures with controllable interfaces. This work serves as a referencing significance for the development of lightweight multi-functional electromagnetic absorbing materials.

Size-regulated Co-doped hetero-interfaced 3D honeycomb MXene as high performance electromagnetic absorber with anti-corrosion performance

It is desirable to develop electromagnetic (EM) wave absorbers with anti-corrosion property that can suit various electronics, telecommunications, and military applications in harsh conditions. In this work, by varying the Co content in the 3D honeycomb MXene, Co/MXene composites with remarkable EM absorption performance were obtained. In particular, Co/MXene with 0.5 mmol Co displayed a minimum reflection loss (RL) of –54.3 dB at 2.34 mm and broad absorption bandwidth of 5.92 GHz at 2.02 mm. These Co/MXene composites also showed high resistance to corrosion as evidenced by very low corrosion current densities (10−6 ∼ 10−7 A cm−2) and very large polarization resistances (107 ∼ 108 Ω) when exposed to various corrosive conditions (acid, neutral, and alkaline conditions). The unique honeycomb architecture and the combined presence of Co and MXene enabled the electron transfer from Co to MXene as revealed by density functional theory simulation and suppressed the contributions from magnetic and conductive losses, thus allowing only polarization loss-originated EM dissipation behavior. Accordingly, this study introduces a simplified model to elucidate the mechanism of EM absorption, offering insights at the nano level.

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.