Electromagnetic Wave Absorption Performance Research Articles

Hierarchical heterostructure Ni2P hollow carbon spheres derived from MOFs for efficient electromagnetic wave absorption

In this study, a hierarchical heterogeneous structure of Ni2P hollow carbon spheres (Ni2P-HCS) was synthesized through a two-step process involving carbonization and phosphorization of Ni-metal organic framework (Ni-MOF) precursors. During the construction of the Ni2P/C nanostructure, heterointerface recombination and secondary graphitization were observed, which contribute to the modulation of interface polarization. Structural analysis revealed that the Ni2P/C nanoparticles are uniformly dispersed, forming stable porous structured microspheres, thereby leveraging dielectric and magnetic losses. The combination of Ni2P with metal-organic frameworks (MOFs) can optimize impedance matching, enhance effective absorption bandwidth, and consequently improve electromagnetic wave absorption performance. The results show that Ni2P-HCS (Ni2P-HCS700) exhibited superior electromagnetic wave (EMW) absorption characteristics when the carbonization temperature is 700 ℃. It achieves a maximum reflection loss (RL) of −46.7 dB at a thickness of 2.9 mm and an effective absorption bandwidth (EAB) of 4.8 GHz at 1.71 mm thickness, almost covering the Ku-band (13.3 GHz−18 GHz). Radar cross-section (RCS) simulations utilizing CST indicated an optimal RCS reduction value of 41 dB m² at theta=0° for Ni2P-HCS700. This work introduces a universal approach to designing high-performance lightweight absorbers derived from MOFs, incorporating transition metal phosphides to form composites for impedance matching control.

Modulation of impedance matching of hollow cubic carbon with semi-closed structure for effective microwave absorption

In this paper, a certain degree of semi-closed structure was successfully introduced in hollow cubic carbons (HCCs) by selective dissolution of phenolic resin (PR)/NaCl precursor by acetone. The impedance matching of the HCCs absorber was improved, which in turn lead to the enhancement of the electromagnetic wave absorption capacity. By controlling the selective dissolution time of acetone, HCCs with different degrees of integrity were formed, and the degree and mechanism of the influence of the semi-closed structure of HCCs on the wave absorbing properties were investigated by analyzing the microstructure and physical phase composition of HCCs. From the scanning electron microscope photographs, it can be seen that with the increase of the acetone treatment time of HCCs, the samples gradually appeared a certain degree of semi-closed structure. With the extension of the acetone treatment time to 60 min, the structure of the HCCs was seriously damaged, at which time the impedance matching of the wave-absorbing materials was seriously deteriorated, and the electromagnetic wave absorption performance was also decreased. Among them, the electromagnetic wave absorption performance of HCCs30min is the most outstanding, specifically, when the loading rate is 10 wt%, the maximum absorption peak value of HCCs30min with a thickness of 2.7 mm reaches −41.1 dB, and the corresponding absorption bandwidth is 3.8 GHz (8.9 GHz–12.7 GHz). The experiment confirms that the existence of the degree of structural integrity can affect the impedance matching and wave absorption performance of HCCs.

Construction of two-dimensional thick sheet-like carbide and Co nanocrystals heterostructure toward efficient electromagnetic wave absorption

Deeply studied the electromagnetic wave absorption (EWA) mechanism of Mo2C heterostructure is crucial for realizing the application of Mo2C-based materials in new multifunctional integrated microwave absorbing coatings. In order to exclude the influence of special three-dimensional morphology (spherical, hollow, etc) on EWA performance, we designed the two-dimensional (2D) thick sheet-like Mo2C/Co@NC heterostructure that composed of molybdenum carbide (Mo2C), cobalt (Co) nanoparticles and nitrogen-doped carbon (NC), derived from the MoO42− substituted 2D sheet-like Co zeolite imidazolate frameworks (Mo/Co BIFs). The Mo2C/Co@NC has better EWA performance than Co@NC and Mo2C@NC. In the thickness range of 2∼4 mm, the effective absorption bandwidth can cover up to 10.5 GHz, and the strongest absorption can reach −48 dB. Behind the excellent EWA performance, multiple polarization relaxation and enhanced interface polarization are acting together. Moreover, the structure and interface effects of Mo2C/Co heterojunction are also revealed by DFT calculation. This work provides a workable methodology for manipulating the heterogeneous interface of MOFs-derived Mo2C based material and understanding the EWA mechanism of Mo2C-based heterostructure.

Excellent microwave absorption property of 3D printed SiCN matrix metamaterial

The combination of 3D printing, polymer derived ceramics, and electromagnetic wave (EMW) absorption metamaterials is particularly useful for spacecraft stealth in extreme environments and is gradually gaining significant interest. While the 3D printing of SiOC has been extensively researched, the high temperature stability and mechanical performance of SiOC are not as favorable as SiCN. However, it remains challenging to prepare SiCN metamaterials with both high mechanical and microwave absorption properties by 3D printing. Herein, we demonstrate a SiCN EMW absorption metamaterial with high mechanical properties using digital light processing 3D printing, which achieves a minimum reflection loss of −31.01 dB (99.9 % absorption), and the widest effective absorption bandwidth covers the entire X-band from 8.2 to 12.4 GHz. And the EMW absorption performance can be adjusted based on the size of the unit structure.

Application of MOF derived porous carbon to regulate electromagnetic wave absorption performance and mechanism of ZnFe2O4@ZnO

The incorporation of metal-organic frameworks (MOFs) and subsequent high-temperature treatment to form derived carbon composite materials represents a promising research direction for tuning the electromagnetic wave absorption performance of composite materials. In this study, ZnFe2O4@Zn-MOF was synthesized using sol-gel and in-situ growth methods, and a tunable carbon content porous ZnFe2O4@ZnO/C composite material was prepared by varying the heat treatment temperature under an Ar atmosphere. The formation of MOF derived carbon enhanced the dielectric loss capability of the material, thereby optimizing the impedance matching of the composite and improving its electromagnetic wave attenuation capacity, ultimately leading to improved absorbing performance. The ZnFe2O4@ZnO/C composite material treated at 800 °C exhibited the most outstanding absorption performance, achieving a reflection loss of −50.89 dB at a frequency of 11.8 GHz and an effective absorption bandwidth of 3.588 GHz with a thickness of 1.6 mm, demonstrating excellent electromagnetic wave absorption capability.

Single‐Atom Nanozyme‐Like Lanthanum Moieties for High‐Performance Electromagnetic Energy Absorption

AbstractSingle‐atom (SA) nanozymes have unprecedented physicochemical performance due to their integrated merits of both atomically dispersed metal atoms and bio‐enzymes. However, the structure‐function relationship between the SA nanozyme‐like structure and its dielectric performance is still unclear. Furthermore, controllable synthesis of SA nanozyme‐like structures remains challenging due to their unique five‐coordinated configurations. Here, a dicyandiamide‐mediated pyrolysis strategy is proposed to anchor five nitrogen‐coordinated lanthanum (La)–N5 moieties on interconnected N‐doped graphene nanocages (La‐N5/ING). Theoretical predictions indicate that the spatially coordinated La–N5 moieties exhibit significantly enhanced conduction loss and polarization loss compared to La–N4 moieties, as evidenced by the experimental results. Moreover, the polydimethylsiloxane‐coated chemically cross‐linked film constructed by the La‐N5/ING and aramid nanofibers has outstanding electromagnetic wave (EMW) absorption performance with an effective absorption bandwidth (EAB10) of 6.24 GHz at a thickness of merely 2.0 mm, outperforming those of most reported carbon‐based films. Importantly, the film also has excellent flexibility, hydrophobicity, mechanical strength, and structural stability, ensuring its application potential in practical environments. These findings provide crucial insights into the microscopic environment of SA on the dielectric properties of their host materials, and a critical method for the preparation of multifunctional films with spatial coordinated SA.

Synthesis of Air@Co@Co7Fe3@Fe3O4 composite with enhanced electromagnetic wave absorption performance

Electromagnetic pollution prevention and military stealth technology requirements for wave absorbing materials gradually increased, therefore, the research and development of absorbing materials with the merits of low reflection loss, wide effective absorption bandwidth, and lightweight is of great significance. In this work, Air@Co@Co7Fe3@Fe3O4 hollow spherical particles have been successfully synthesized via a simple chemical plating method combined with a post heat treatment. It reveals that the Air@Co@Co7Fe3@Fe3O4 particles with a loading of 50 wt % exhibits an optimum reflection loss (RL) value of −20.77 dB at 15.52 GHz and broad effective absorption bandwidth (EAB, RL ≤ −10 dB) of 4.56 GHz with a thickness of 1.4 mm. Compared to Air@Co hollow spherical particles, Air@Co@Co7Fe3@Fe3O4 particles with natural resonance and eddy current loss, as well as the interlayer interfacial polarization mechanism of the multilayer structure, exhibit superior electromagnetic wave(EMW) absorption capabilities. The Air@Co@Co7Fe3@Fe3O4 hollow spherical particles could be a new highly efficient absorbing material for electromagnetic waves.

Bead-like Co/C@MoS2Composites connected by Multi-Walled carbon nanotubes for high-efficiency electromagnetic wave absorption

This study presents a novel approach to synthesize a composite material composed of bead-like Co/C nanoparticles anchored on MWCNTs, encapsulated by MoS2 nanosheets through a combination of carbonization and hydrothermal treatment using ZIF-67 as the precursor. The resulting composite demonstrates exceptional electromagnetic wave (EMW) absorption performance, with a minimum reflection loss (RL) of −63 dB at a thickness of 2.44 mm and an effective absorption bandwidth (EAB) of 7.2 GHz when RL is below 10 dB together with an expanded EAB of 12.3 GHz (d = 5 mm).The superior absorption capabilities arise from a well-thought-out design of material composition and structure. The synergy of Co/C and MWCNTs enhances ferromagnetic resonance, conductivity, and polarization loss, while sulfur vacancies in MoS2 act as polarization centers, facilitating dipole polarization and efficient conversion of electromagnetic wave energy. The core–shell structure and heterogeneous interfaces introduce various energy loss mechanisms, including multiple polarizations, scattering effects, and dielectric loss. This work introduces a facile method for synthesizing a composite material with outstanding EMW absorption performance. The synergistic combination of unique material components and the carefully engineered structure make this composite a promising candidate for advanced applications in electromagnetic wave absorption technology.

Regulating the Electronic Structure of MAX Phases Based on Rare Earth Element Sc to Enhance Electromagnetic Wave Absorption.

MAX phases are highly promising materials for electromagnetic (EM) wave absorption because of their specific combination of metal and ceramic properties, making them particularly suitable for harsh environments. However, their higher matching thickness and impedance mismatching can limit their ability to attenuate EM waves. To address this issue, researchers have focused on regulating the electronic structure of MAX phases through structural engineering. In this study, we successfully synthesized a ternary MAX phase known as Sc2GaC MAX with the rare earth element Sc incorporated into the M-site sublayer, resulting in exceptional conductivity and impressive stability at high temperatures. The Sc2GaC demonstrates a strong reflection loss (RL) of -47.7 dB (1.3 mm) and an effective absorption bandwidth (EAB) of 5.28 GHz. It also achieves effective absorption of EM wave energy across a wide frequency range, encompassing the X and Ku bands. This exceptional performance is observed within a thickness range of 1.3 to 2.1 mm, making it significantly superior to other Ga-MAX phases. Furthermore, Sc2GaC exhibited excellent absorption performance even at elevated temperatures. After undergoing oxidation at 800 °C, it achieves a minimum RL of -28.3 dB. Conversely, when treated at 1400 °C under an argon atmosphere, Sc2GaC demonstrates even higher performance, with a minimum RL of -46.1 dB. This study highlights the potential of structural engineering to modify the EM wave absorption performance of the MAX phase by controlling its intrinsic electronic structure.

Compositional design of C-coated multi-elemental alloy nanoparticles for superior microwave absorption

Exploring improved electromagnetic wave absorption performance in magnetic components involves capitalizing on dual dielectric relaxation and multiple magnetic resonances, ultimately giving rise to a dielectric-magnetic matching effect. Herein, a one-step Metal-organic Chemical Vapor Deposition (MOCVD) method has been utilized to fabricate C-coated ternary and quaternary alloy nanoparticles (FeCoNi, FeCoNiCu, FeCoNiMg, and FeCoNiMn) with tunable magnetization. The results affirm that the capabilities of impedance matching and electromagnetic wave attenuation can be significantly regulated by compositing nanoparticles with different elements. The optimized C-coated FeCoNiMg nanoparticles demonstrate an exceptional capacity for electromagnetic wave attenuation, achieving a reflection loss value of −51.8 dB at a matched thickness of 2.9 mm. Moreover, the absorption bandwidth significantly broadens to 7.60 GHz (10.4 – 18.0 GHz) with a thickness of 2.7 mm. The exceptional performance in electromagnetic attenuation is credited to the dielectric loss and improved impedance matching characteristics induced by the C-coated FeCoNiMg nanoparticles. The findings from this study will be beneficial in the development of lightweight and highly effective electromagnetic wave absorbers using magnetic alloy nanoparticles.

Porous CoZn@NC skeletons supported NiCo2S4 nanorods for efficient electromagnetic wave absorption

Bimetallic sulfides are promising in electromagnetic wave (EMW) absorption due to their moderate permittivity and high dielectric loss. However, the impedance mismatching and insufficient loss mechanism of bimetallic sulfides result in limited EMW absorption performance. Herein, bimetallic sulfide (NiCo2S4) nanorods were loaded onto nitrogen-doped carbon embedded with CoZn nanoparticles (CoZn@NC) derived from CoZn-based metal organic framework (CoZn-MOF) through simple hydrothermal and vulcanization processes. Importantly, during the vulcanization process, CoZn@NC undergoes structural reorganization and evolves into defect-rich porous nanosheets, which promotes dipole polarization and enhance EMW absorption ability. Additionally, the formed NiCo2S4 nanorods are tightly anchored on the porous CoZn@NC skeletons, forming a large number of heterostructures, and promoting interfacial polarization. In addition, the carbon nanotubes (CNTs) formed during the pyrolysis process of CoZn-MOF contribute to the conduction loss of the heterostructure and motivate dielectric loss. Therefore, CoZn@NC/NiCo2S4 heterostructures inherit excellent EMW absorption performance and obtain a reflection loss (RL) value of −32.53 dB at a matching thickness of 2.1 mm, while exhibiting an effective absorption bandwidth (EAB) of 4.1 GHz. Radar cross-sectional area (RCS) simulation shows that the potential of CoZn@NC/NiCo2S4 heterostructure in practical anti radar detection. This work puts up great potential for the development of advanced bimetallic sulfides-based EMW absorbers.

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.

Hollow core–shell Co@SiO2@PPy composites with efficient electromagnetic wave absorption

In this study, hollow Co@SiO2@PPy composites with excellent electromagnetic wave (EMW) absorption performance were successfully synthesized. The monodisperse hollow Co microspheres were prepared using a solvent-thermal method. The microspheres were then coated with an SiO2 layer by a modified Stöber method. Finally, the SiO2 layer was surface-coated by polypyrrole (PPy) through in-situ polymerization to obtain Co@SiO2@PPy composite materials with hollow core–shell structures. The prepared CSP2 composite achieved a minimum reflection loss (RLmin) of −65.83 dB at 1.86 mm, demonstrating an effective absorption bandwidth (EAB) of 4.84 GHz. The CSP3 composite achieved a widest EAB (EABmax) of 5.4 GHz at a thickness of 1.83 mm, while simultaneously maintaining the RL level at −50.70 dB. Additionally, it demonstrated an RLmin value of −61.66 dB with a thickness as thin as 1.66 mm. The observed shift of FTIR absorption peaks by 20 cm−1 in the PPy ring provides compelling evidence for the involvement of multilayered structures in polarization loss. The SiO2 layer not only enhances the interface polarization but also prevents corrosion of the Co core by acidic solutions. The exceptional EMW absorption characteristics can be attributed to the effective impedance matching and the combined effect of magnetic and dielectric losses.

Analysis of influence of deep processing of metallic mineral materials on electromagnetic wave absorption performance

In this paper, the effects of deep processing of metallic mineral materials on electromagnetic wave absorption properties were studied. Firstly, the background and significance of the research are introduced, and the importance of metallic mineral materials in the field of electromagnetic wave absorption is expounded. Then the basic principle of electromagnetic wave absorption and the characteristics and influencing factors of metal mineral materials are discussed. In the section of deep processing technology, different processing methods and their applications are listed. Through experimental design and method, the electromagnetic wave absorption properties of metal mineral materials after deep processing are tested and analyzed. The experimental results are obtained and discussed. Finally, the application prospect of metallic mineral materials in electromagnetic wave absorption field is prospected, and the technical improvement and future development direction are put forward. This study provides an important reference for deepening the understanding of electromagnetic wave absorption properties of metallic mineral materials, and provides a reference for further research in related fields.

Effects of Functionalized Layered Structure on Electromagnetic Wave Absorption Performance of Magnesium Phosphate Cement

Effects of Functionalized Layered Structure on Electromagnetic Wave Absorption Performance of Magnesium Phosphate Cement

IIIA-IIB multicomponent perovskite rare earth ferrites with promising electromagnetic wave absorption properties

Perovskite-type rare-earth ferrites (REFeO3) are promising materials for absorbing electromagnetic (EM) wave pollution. However, insufficient dielectric loss and poor impedance matching are key factors that limit the broader implementation of REFeO3. Herein, a series of multicomponent perovskite-type ferrites with strong EM wave absorption capabilities was prepared. Through the synergistic effect of chemical constitution regulation and entropy regulation, optimization of the dielectric loss and impedance matching is achieved by strengthening the structural defect mechanism, thus further adjusting the EM wave absorption performance. Compared with (LaGdSmNdBa)FeO3 (HE-1) and (LaGdPrSmNdBa)FeO3 (HE-2), (LaGdBa)FeO3 (ME-1) and (LaGdSmBa)FeO3 (ME-2) exhibit favorable performance, with optimal minimum reflection loss (RLmin) of −56.35 dB (at 11.12 GHz) and −63.25 dB (at 7.22 GHz) and effective absorption bandwidth (EAB) of 4.46 and 4.72 GHz, respectively. This multicomponent design provides a new strategy for the development of EM wave absorption materials.

2D/3D structure engineering of dual-phase Mo2C/MoO2-decorated rGO aerogels for electromagnetic waves absorption

The rational design of structure and regulation of composition in micro/nano-scale is of great significance for broadband absorbing properties of lightweight aerogels. Herein, the controllable dual phase Mo2C/MoO2-decorated rGO aerogels are prepared by designing the Mo-rGO precursor, which possesses heterostructure interfaces and three-dimensional structures. The dual-phase of Mo2C/MoO2 was controlled and nanoparticles were dispersed on the surface of graphene. The interconnected rGO sheets construct continuous network for electron transport, which facilitates conduction loss and multiple reflections inside the aerogel. The Mo2C/MoO2 nanoparticles decorated on rGO sheets contribute sufficient interfacial and dipole polarization, and improve the impedance matching and strengthen the loss capacity of electromagnetic waves. The as-prepared Mo2C/MoO2/rGO aerogel exhibits considerable electromagnetic wave absorption performance with a minimum reflection loss of −42.1 dB at 12.5 GHz and an effective absorption bandwidth of 5.6 GHz (10.6–16.2 GHz) at a thin thickness of 2.2 mm with a low density of 9.8 mg·cm−3. This Mo2C/MoO2/rGO aerogel would be a promising material for electromagnetic wave absorption in wide application fields, and it also provides a universal idea for constructing low-density broadband microwave absorption material by structural and composition engineering.

Urchins CuCo2S4/Carbon composites with abundant defects and hetero-interfaces for optimized impedance matching and broadened effective band width

This work adopts a composite strategy combining “large anisotropic structure” and “strong dielectric material”, which is a pioneer work reported on urchins CuCo2S4/C absorber. An environmentally friendly (eco-friendly) CuCo2S4/C composites were prepared through a facile route including an ion exchange method and a simple physical grinding process. The resultant CuCo2S4/C composites exhibit an urchins-like morphology with carbon nanoparticles anchored randomly on the tentacles of the urchins. The urchins CuCo2S4/C composites display an optimal reflection loss value of −44.2 dB at the thickness of 2.2 mm, and the effective bandwidth with RL < −10 dB reaches 7.12 GHz at a thickness of 2.4 mm. The outstanding electromagnetic (EM) wave absorption performance is mainly benefited from the synergistic effects between the anisotropic structure of CuCo2S4 and conductive carbon particles. By adjusting the component ratio during the grinding process, an optimized combination of conduction loss and polarization loss can be achieved, and the impedance matching level can be regularly controlled and improved while increasing the effective absorption bandwidth. These results indicate that the sea urchin CuCo2S4/C composite material designed in this work can serve as an ideal candidate for high-performance electromagnetic wave absorption and has certain reference significance for the development of more sulfide semiconductor based absorbing materials.

The Ag based composites derived from Ag-MOFs with tunable forms for electromagnetic wave absorption

The wireless communication and network technology make our lives more and more convenient. However, the inevitable electromagnetic pollution and interference deriving from these technologies have hazardous influences on the electronic equipment and human health. Therefore, continuous explorations have been strived to fabricate excellent electromagnetic wave (EMW) absorbers to diminish the impact of these negative effects. MOF, as an emerging hybrid material is widely investigated as the EMW absorber due to its multiple attenuation mechanisms. However, attentions are always focused on the influence of different inorganic ions and organic linkers on the electromagnetic wave absorption (EMWA) performance of MOF. Significantly, tremendous facts have proved that the control of morphologies and forms of hybrid materials is vital for further enhancement of many applications. Hence, the investigation of effect of MOF forms on EMWA performance will be the important foundation for further explorations. Here, three different forms of Ag based MOFs, named Ag-MOF, Ag-MOF-Microcrystal and Ag-MOG were successfully fabricated. Further investigations of XPS, XRD as well as FT-IR manifested that these three materials had the same coordination behaviors. The different forms could be obtained by the controlling of crystallization. Ag-MOG was proved to be the best EMW absorber among the fabricated materials. The minimum RL of −41.8 dB and a wider EAB of 6.3 GHz could be obtained by Ag-MOG derived composite.

Volume exclusion effect and ambient temperature induced ultrahigh electromagnetic wave absorption properties of polylactic acid (PLA)/graphene nano‐platelets (GNPs) composites

AbstractConductive polymer composites (CPCs) have an excellent performance in dealing with electromagnetic (EM) radiation. The distribution of conductive fillers in CPCs plays a vital role in the electrical conductivity and EM wave‐absorbing properties. Moreover, the distribution evolution of GNPs in the PLA matrix caused by the enhanced volume exclusion effect via annealing was investigated. Polylactic acid with 8 wt.% graphene nano‐platelets (PG8) achieved best performance among the composites. After 5‐min heat treatment, the electrical conductivity and EM wave absorption properties of PLA/GNPs composites are significantly improved. With a simple treatment, the composite can reach an ultrahigh reflection loss (RL) value of −28.5 dB with a thickness of only 2.5 mm. By controlling the thickness in the range of 1–4 mm, the effective absorption bandwidth can be adjusted within 5.1–8.0 GHz. These methods provided in this work can effectively improve the EM wave absorption performance of CPCs and are worthy of being promoted.