Minimum Reflection Loss Value Research Articles

Self-assembly Ti3C2Tx MXene/ZnCo2O4@ZnO heterostructure with Schottky junction for regulating BIEF to enhance microwave absorption

Currently, heterogenous interface engineering on absorbers is shown to boost the electromagnetic wave absorption (EMA) performance effectively. However, challenges remain in investigating the mechanisms by studying heterojunctions between heterogeneous interfaces. Herein, a self-assembly Ti3C2Tx MXene/ZnCo2O4@ZnO (MZCZ) heterostructure with abundant Schottky heterogenous interfaces generating a controllable built-interface electric field (BIEF) effect is fabricated to achieve exceptional EMA ability. The formative BIEF between the unbalanced distribution charges promotes charge separation and migration, increasing polarization loss. Fortunately, the obtained MZCZ1 exhibits the reflection loss (RL) value of −69.78 dB under the ultralow thickness of 1.501 mm and the optimal minimum RL (RLmin) value of −74.41 dB, respectively. The excellent performance can be ascribed to the multiple polarization loss, conduction loss, natural resonance, and exchange resonance characteristics. Moreover, by the Computer Simulation Technology (CST) software, the designed circular cone and circular truncated cone periodicity structure with the MZCZ1 absorber both exhibit a super-wide effective absorption bandwidth (EAB) covering the whole C, X, and Ku band. This study can pioneer a novel approach to developing functional EMA materials and provide a valuable direction for further study of EMA mechanisms at heterogeneous interfaces.

Multi-heterogeneous interfaces boost dielectric polarization in PBA-derived Co/MnO@NC ternary composites for electromagnetic wave absorption

The elaborate construction of multi-component composites has been deemed as a promising strategy to enhance dielectric polarization response capability in the preparation of highly efficient microwave absorbers. However, the rational design and integration of homogeneous composites with diverse components continues to pose a great challenge. Herein, we propose a straightforward self-assembly-carbonization strategy for fabricating Co/MnO@NC ternary composites derived from CoMn-Prussian Blue Analogous precursors, featuring enriched heterogeneous interfaces and balanced magneto-electric coupling synergy. The ternary composites effectively introduce diverse dissipation mechanisms, including interfacial polarization behavior originated from the constructed heterogeneous interfaces, dipole polarization relaxation triggered by atomic defects, and optimized magnetic loss ability from well-dispersed metallic Co species. Benefiting from these advantages, the Co/MnO@NC composites demonstrate superior electromagnetic wave absorption performances, with a minimum reflection loss value of −61.37 dB at the thickness of 3.5 mm and effective frequency absorption bandwidth of 6.32 GHz, covering the full Ku-band. Furthermore, power loss density and radar cross-section simulations validate that the Co/MnO@NC ternary composites possess exceptional microwave signal attenuation abilities, with a maximum radar cross-section reduction value of up to 27.98 dBm2 at 0°. Such outstanding absorption properties exceed those of most currently reported ternary composites and exhibit significant potential to replace conventional ferromagnetic-based absorbers. This work offers a straightforward strategy to fabricate ternary composites with excellent electromagnetic wave attenuation properties and sheds novel insights into the dissipation mechanisms.

Regulating the phase composition and microstructure of Fe3Si/SiC nanofiber composites to enhance electromagnetic wave absorption

The rational introduction of multi-components to fabricate electromagnetic wave absorbing (EMA) materials with synergistic conductive/dielectric/magnetic losses promises lightweighting and excellent EMA performance, but it remains a challenge. In this work, multicomponent Fe3Si/SiC nanofibre composites with network structure were constructed by electrostatic spinning method and in-situ carbothermal reduction strategy. Design of microstructures and multicomponent modulation by controlling the carbothermal reduction temperature. As a result, the presence of a large number of non-homogeneous interfaces, three-dimensional (3D) conductive network structures and defect structures in Fe3Si/SiC nanofibre composites induces a combination of multiple loss mechanisms that significantly improve the EMA performance. When the filling amount of Fe3Si/SiC in the paraffin transmission matrix is 20 wt%, the maximum effective absorption bandwidth (EABmax) of the fabricated material reaches 5.84 GHz with a thin thickness of 2.02 mm. Moreover, the minimum reflection loss (RLmin) value at 10.96 GHz is as low as −67.57 dB. Meanwhile, the radar cross-section (RCS) simulation verifies that the F-4 peak RCS is reduced to −30.37 dB in the range of −60°<θ < 60°. It indicates that the Fe3Si/SiC nanofiber composites have a good radar-wave dissipation capability in practical applications. In summary, the comprehensive performance of lightweight multicomponent Fe3Si/SiC nanofiber composites can meet the new application requirements and is expected to become an emerging multifunctional wave-absorbing material suitable for harsh environments.

Ingeniously construction of industrial carbon fiber/nickel-iron layered double hydroxide heterostructure composite for high-efficient microwave absorption in aircraft

To enhance the survivability of military aircraft in electromagnetic warfare, carbon fiber/nickel-iron layered double hydroxide (CF/NiFe-LDH) composites with heterogeneous structure were constructed starting from the raw industrial carbon fiber (CF) by electrostatic self-assembly. By reasonably adjusting the mass ratio of CF and NiFe-LDH, the voids formed by LDH arrays stacked on the fiber surface are utilized to promote reflection and scattering of electromagnetic wave (EMW), optimizing impedance matching, as well as synergize dielectric-magnetic dual loss mechanism. Moreover, interfacial polarization effect induced by the abundant heterogeneous interfaces significantly enhance the ability of EMW dissipation. The optimized CF/NiFe-LDH heterostructure composite exhibits the minimum reflection loss (RLmin) value of −52.48 dB at mere 1.77 mm thickness and an expansive maximum effective bandwidth (EABmax) of 7.29 GHz at 2.14 mm. In addition, the computer simulation technology (CST) revealed that the radar scattering cross section (RCS) reduction of composites reaches up to 26.92 dBm2 at an incidence angle of 90°, demonstrating their excellent radar attenuation capability. Tremendously, the heterogeneous composites achieve an SRL1 value of 524.8, which is appreciably better than most of the EMW absorbing materials. The wondrous characteristics including lightweight, ultra-thin, high-efficient microwave absorbing ability of CF/NiFe-LDH heterostructure composites display potential application in fighter aircraft.

Rapidly synthesizing magneto-thermal adjustable high entropy alloy nanoparticles on carbon fiber surface for enhancing electromagnetic wave absorption, thermal conductivity and interface compatibility of composites

It is a significant challenge to develop a fast carbon fiber (CF) surface modification method that could generate a simple multifunctional CF surface, especially in the field of electromagnetic wave (EMW) and thermal regulation. Herein, the FeCoNiAlMn high-entropy alloy (HEA) nanoparticles modified CF (HEA-CF) was successfully prepared by microwave induced carbon thermal shock (MCTS) in a few seconds. The HEA-CF possessed magneto-thermal adjustability by controlling the elemental composition and crystal structures of HEA nanoparticles. It exhibited outstanding dielectric-magnetic loss and phonon heat transfer capability. Moreover, HEA nanoparticles and cellulose nanofibers on CF surface also formed multiscale interfacial reinforced structure. Consequently, HEA-CF/Polyamide 6 (PA6) composites demonstrated extraordinary versatility. MCTS5s-CF/PA6 exhibited the strongest absorption with minimum reflection loss value of −63.6 dB at 2.4 mm thickness. The maximum effective absorption bandwidth reached 6.67 GHz with thickness of only 1.9 mm. Compared with that of untreated-CF/PA6 composite, the thermal conductivities of MCTS4s-CF and MCTS5s-CF/PA6 composites increased by 45.2 % and 19.1 %. Simultaneously, the tensile strength of MCTS4s-CF/PA6 and MCTS5s-CF/PA6 composites increased by 19.5 % and 16.1 %. This new approach provided an effective way to realize multifunctional composites. Its low-cost, efficient and environmentally friendly process had great potential for large-scale production.

Coconut shell waste-based ZnFe2O4/PANI/rGO nanohybrid composites as excellent radar-absorbing material

In this work, we developed ZnFe2O4/PANI/rGO nanocomposites based on coconut shell waste through in situ polymerization as excellent radar-absorbing material (RAM). This research mainly focused on adjusting the ZnFe2O4 content to obtain optimal absorption of radar waves, especially in the X-band. The results showed that the diffraction pattern of the ZnFe2O4/PANI/rGO nanocomposites showed multiple phases (crystalline and amorphous), which increased the ZnFe2O4 content and affected the increasing diffraction intensity. The functional group of the ZnFe2O4/PANI/rGO nanocomposites was identified with the presence of the M–O group originating from ZnFe2O4 at wavenumbers 517 and 419 cm−1 of Zn–O and Fe–O groups, respectively. Meanwhile, quinoid and benzenoid rings from PANI and CO from rGO were identified at wavenumbers 1580, 1504, and 1710 cm−1, respectively. The morphology of the ZnFe2O4/PANI/rGO nanocomposites showed PANI was distributed on the ZnFe2O4 nanoparticles, which were subsequently deposited on the rGO. The ZnFe2O4/PANI/rGO nanocomposites exhibited superparamagnetic properties, as confirmed by their coercivity values ranging from 9.2 to 124.4 Oe. Interestingly, the ZnFe2O4/PANI/rGO nanocomposites with the P3 sample showed optimal RAM performance with a minimum reflection loss value of −39.8 dB at 7.6-GHz frequency with an effective absorption bandwidth of 1.1 GHz.

Engineering multifunctionality graphene-based nanocomposites with epoxy-silane functionalized cardanol for next-generation microwave absorber

As technology advances, the demand for effective microwave-absorbing materials (MAM) to mitigate electromagnetic wave interference is growing. Two-dimensional (2D) materials are increasingly favored across various fields for their high specific surface area, electrical conductivity, low density, and dielectric loss properties. This study presents lightweight nanocomposites composed of graphene nanoplatelets blended with epoxy resin (ER) and cardanol with silane-functionalized (SFC) as a toughening agent. The resulting nanocomposites exhibit a high surface roughness of 130 nm and an enhanced hydrophobicity, as evidenced by a high contact angle. Notably, the ER/SFC/GNP sample at 3 wt% (0.075 g) achieves a minimum reflection loss value of −18 dB at a thickness of 10 mm, indicating improved impedance matching and enhanced dielectric loss capability. The increasing damping factor ratio to approximately 0.95 further augments the reflection loss performance. The research aims to develop cost-effective, efficient, lightweight graphene-based nanocomposite absorbers.

Synchronously Formed Hetero- and Hollow Core-Branch Nanostructure Toward Wideband Electromagnetic Wave Absorption.

The intrinsic limitation of low electrical conductivity of MoSe2 resulted in inferior dielectric properties, which restricts its electromagnetic wave absorption (EMWA) performances. Herein, a bimetallic selenide of MoSe2/CoSe2@N-doped carbon (NC) composites with hollow core-branch nanostructures are synthesized via the selenization treatment of MoO3 nanorods coated with ZIF-67. By adjusting the mass ratio of ZIF-67 to MoO3, the electromagnetic parameters and morphologies of composites are finely tuned, further ameliorating the impedance matching and EMWA performances. The involvement of NC improves the electronic conductivity of the composites. The synchronously formed heterostructure not only facilitates charge transfer but also leads to the accumulation and uneven distribution of charges, thus enhancing the conductive loss and polarization loss. The hollow core-branch nanostructure provides abundant conductive networks, heterointerfaces, and voids, significantly enhancing the EMWA property. Density functional theory implies that the heterostructures effectively boost charge transport and change charge distribution, which heightens the conductive loss and polarization loss. As a result, the composites demonstrate a minimum reflection loss value of -53.53 dB at 9.04 GHz, alongside a maximum effective absorption bandwidth of 6.32 GHz. This work offers invaluable insights into novel structural designs for future research and applications.

Air-microwave simultaneously induced carbon fiber surface oxidation and magnetism adjustment by CoOx nanoparticles rapid assembly for interface enhancement and electromagnetic wave absorption of its composites

It is a significant challenge to develop a fast carbon fiber (CF) surface modification method, especially for the high strength electromagnetic wave (EMW) absorption materials. Herein, magnetic CoOx nanoparticles are successfully synthesized and uniformly assembled on CF surface with high oxygen-containing groups by rapid ambient microwave carbon thermal shock (MCTS). The presence of oxygen defect sites on CF surface promotes CoOx nanoparticles nucleation. The number of oxygen defects and the types of magnetic nanoparticles on the CF surface effectively adjust the surface chemical activity and the electromagnetic properties of CF, which is conducive to improving the EMW absorption performance and interface compatibility of the CoOx nanoparticles modified CF reinforced polyamide 6 (CO@CF/PA6) composites. Compared with CO@CF-0 s/PA6, the tensile strength and modulus of CO@CF-3.5 s/PA6 composite are increased by 18.1 % and 18.6 %, respectively. It also displays a minimum reflection loss value (−59.9 dB) at a thinner thickness of 1.9 mm while the maximum effective absorption bandwidth reaches 5.02 GHz with a thickness of 1.8 mm. Its radar cross-section values exhibit less than −10 dBm2 at all tested detection angles. This rapid MCTS shows great potential for large-scale production of CF modification with low-cost, efficient and environmentally friendly process.

FeSiBCuNbZr amorphous composites decorated with SiO2 and TiO2(B) (bronze phase TiO2) for efficient electromagnetic wave absorption

The application of Fe-based amorphous microspheres in high-performance electromagnetic wave absorbing materials is significantly limited by a single loss mechanism. Utilizing interfacial engineering and magnetic-dielectric synergistic effect is a viable approach to enhance microwave absorption. In this work, FeSiBCuNbZr amorphous microspheres were synthesized using single copper roller melt-spinning method and ball mill method. The finding reveals that the incorporation of SiO2 and TiO2(B) (bronze phase TiO2) shells notably enhances polarization loss and conductive loss. FeSiBCuNbZr@SiO2@TiO2(B) amorphous composites exhibited a minimum reflection loss value of −64.89 dB at a thickness of 2.17 mm and an effective absorption bandwidth (EAB) of 8.08 GHz covering 9–18 GHz at a thickness of 1.9 mm. The exceptional wave absorption performance is ascribed to the combined effect of magnetic loss in the FeSiBCuNbZr amorphous core and dielectric loss from the double-shell structure, while maintaining favorable impedance matching. This work provides a new core–shell FeSiBCuNbZr amorphous composites for efficient electromagnetic wave absorption.

3D-Printed (CoCrFeMnNi)3O4@C-GR dual core–shell composites: Multilevel control and mechanisms of microwave absorption performance

With the rapid development of modern electronic technology, there is an increasing demand for microwave-absorbing materials in various applications. These include reducing electromagnetic interference, enhancing communication quality, and ensuring stealth capabilities for military equipment. This study has developed a novel microwave-absorbing material, which is a composite system consisting of a high-entropy dual-core–shell (CoCrFeMnNi)3O4@C combined with graphene (GR), and is composed of polylactic acid (PLA) as the matrix. The material is prepared through a process involving high-temperature oxidation, carbonization to form the shell, and Powder extrusion molding techniques. The results demonstrate that when the dual-core–shell (CoCrFeMnNi)3O4@C microspheres are added at a loading of 20 wt%, and GR is added at 7 wt%, with a thickness of 2.22 mm, the composite material achieves a minimum reflection loss (RLmin) value of −51.36 dB and an effective absorption bandwidth (EAB) of 5.20 GHz. This excellent performance is attributed to the lattice distortion, a large number of oxygen vacancies, and abundant heterogeneous interfaces and conductive networks within the composites. These factors work together to stimulate multiple relaxation mechanisms, enhance the magnetic loss effect, and greatly improve the microwave absorption capability. The introduction of high-entropy microspheres effectively modulates the high conductivity of GR, further enhancing the comprehensive absorption performance of the material. This study not only offers a new strategy for designing and preparing high-performance microwave-absorbing materials but also establishes a valuable scientific foundation for materials research and application in related fields.

Activating Excellent Electromagnetic Wave Absorption of Micromorphology-Optimized Cu/C Nanocomposite Fibers via a Metal-Organic Framework Template-Assisted Strategy.

Morphological engineering is crucial for conceiving high-efficiency electromagnetic wave (EMW) absorption materials. However, for carbon fiber-based composites, the management of micromorphology is significantly astricted by complex fabrication. It remains highly challenging to clarify the micromorphological influences on the EMW loss mechanism of carbon fiber-based absorption materials. In this work, micromorphology-optimized Cu/C nanocomposite fibers are prepared by virtue of a metal-organic framework (MOF) template-assisted strategy. Through skillfully grafting the morphology-regulation capacity of MOFs onto composite fibers, the Oswald maturation and particle distribution issues of Cu nanoparticles are settled, and the efficient electron transport pathways are established by the bead-like structure of the fiber matrix. Compared to prepared conventional Cu/C nanocomposite fibers, the MOF template-assisted strategy stimulates a remarkable leap in EMW absorption performance. The minimum reflection loss value of Cu/C-40 can reach -64.5 dB, 15.96 times lower than that of a conventional sample (Cu/C-2). The maximum effective absorption bandwidth extends to 6.08 GHz, contrasting the ineffective performance of Cu/C-2. Systematic research demonstrates that the enabled graphite-catalytic function of Cu nanoparticles collaborated with an optimized conductive network structure plays a pivotal role in creating field-induced leakage currents, facilitating conductive loss, the primary contributor to EMW dissipation. This work establishes a correlation mechanism between micromorphology and EMW loss, presenting a compelling example of customizable carbon fiber-based absorbers.

Synthesis of Mo2C/C nanoclusters attached on rGO nanosheets for high-Efficiency electromagnetic wave absorption

It is an effective strategy that constructing composites with a multi-dimensional structure synergistically enhance their electromagnetic (EM) wave absorbing performance. Herein, a high-efficiency EM wave absorber of Mo2C/C nanoclusters uniformly encapsulated in rGO nanosheets (Mo2C/C-rGO) was prepared by a combination of the directing freeze-dry and subsequently carbothermal reaction method. Mo2C/C was in-situ induced from spherical phosphomolybdic acid/polypyrrole (PMo12/PPy) to result in a unique cluster-like microstructure. Abundant heterogeneous interfaces endowed the Mo2C/C-rGO composites with excellent EM wave absorption performance at a low filling ratio of 5 wt%. The minimum reflection loss (RL) value was −49.3 dB at 1.38 mm and the maximum effective absorption bandwidth (EAB, RL<-10 dB) was 5.12 GHz at 1.60 mm. The excellent performance was owing to the lamellar structure and abundant heterogeneous interfaces in Mo2C/C-rGO, lengthening the transmission path of the incident wave, as well as resulting in high conduction loss and interfacial polarization loss. This universal strategy would be extended to other absorbers with multi-interface structures for lightweight and broadband EM wave absorption.

Thin thickness electromagnetic wave absorbent: Fe3O4 decorated carbon nanofibers composite with designable 3D hierarchical architecture

Designable 3D hierarchical architecture with multi-component heterostructure has been built to form a connected network by fully utilizing the advantages of one-dimensional carbon nanofibers. Fe3O4 decorated carbon nanofibers, which exhibited core-shell microstructures, were successfully prepared by solvothermal and electrospinning technology. Their electromagnetic wave absorption (EWA) performances were explored. The morphology which determined the electromagnetic (EM) parameters can be controlled by adjusting the mass ratio of the raw material. The Fe3O4 decorated carbon nanofibers composite showed an excellent absorbing capability. At a thickness of 2.5 mm, the minimum reflection loss (RLmin) value was −28.28 dB. In particular, the widest effective absorption bandwidth (EAB) can reach up to 2.96 GHz at 1.5 mm. It was more surprising that the effective absorption (RL ≤ −10 dB) occurred when the thickness was only 1.0 mm. The absorption mechanism study revealed that the connected structure facilitated the formation of conductive networks, leading to conductive loss, multiple reflection and scatterings, and interfacial polarization loss. The defects that created during carbonization process enhanced the dipole polarization. The generated magnetic loss which mainly consisted of natural resonance and exchanged resonance loss enhanced the attenuation of EW. Moreover, good impedance matching resulting from the synergistic effect of composition and unique porous network also played an important role. The little filler loading and the thin thickness make the composite have a high EWA performance, which is promising for EWA applications.

Constructing MXene-based mixed-dimensional structure with multiple interfaces to optimize dielectric-magnetic synergistic effect for effective electromagnetic wave absorption

Exploring efficient microwave absorbing materials (MAMs) which could convert electromagnetic (EM) energy into thermal energy represents an approbatory vision to reducing EM radiation and interference. Designing of mixed-dimensional structure with multiple interfaces represents the available target to investigate an ideal MAMs, which maximizes the superiority of mixed-dimensional structure in electromagnetic wave absorption (EMWA). Herein, we take full advantage of multiple interfaces engineering of MXene for optimizing the impedance matching to improve EMWA, MXene-based mixed-dimensional structure was designed by incorporating three-dimensional Fe3C@Carbon layers coated zero-dimensional Fe3O4 nanoparticles (NPs) supported two-dimensional MXene nanosheets (MXene/Fe3O4@Fe3C@Carbon, MFC). The Fe3O4@Fe3C@C with Core@shell structure arrests the essentially self-restacked of MXene and provides various attenuation mechanisms for the incident electromagnetic waves (EMWs). By regulating the carbonization temperature, the MFC exhibits enhanced EMWA property which is attributed to the characteristic structure and optimized dielectric-magnetic synergy effect. The minimum reflection loss (RLmin) value of MFC can reach to −64.3 dB with a matching thickness of 1.73 mm. Otherwise, the maximum effective absorption bandwidth (EAB) (RLmin < -10 dB) reaches 6.42 GHz at only 1.5 mm. Thus, our study refers a novel-fire enlighten to develop excellent mixed-dimensional microwave absorbent based on MXene.

Preparation and microwave absorption performance of SiC aerogel via sol-gel and carbonization reduction process

SiC aerogel presents several advantageous features like lightweight and high temperature resistance when applied as microwave absorbing material. In this paper, SiC aerogel was prepared eventually followed by the sol-gel and carbonization reduction process. The results showed that the effective electromagnetic microwave absorption capacity of SiC aerogel was highly increased after being pyrolyzed at 1500 °C, which presented a minimum reflection loss value of −57.80 dB at 3.10 mm and 9.86 GHz. Besides, the electromagnetic parameters of SiC aerogel with different paraffin ratios were discussed as well as the varying electromagnetic microwave absorption performances. The minimum reflection loss value first rose then fell as the SiC/paraffin ratio increased, which demonstrated the importance of SiC content. This study establishes the theoretical foundation for the subsequent functional application of SiC aerogel.

High-performance electromagnetic wave absorption in VS2@multi-walled carbon nanotube composites

In this work, composites comprising VS2 and multi-walled carbon nanotubes (MWCNTs) were prepared using a simple hydrothermal method. The MWCNTs were dispersed among the VS2 nanosheets, which produced dipole polarization and interfacial polarization, thus enhancing the dielectric loss. Meanwhile, the electrical conductivity of the composites gradually increased with the rising content of the MWCNTs, which improved the electromagnetic wave absorption performance. By adjusting the mass ratio of VS2 to MWCNTs to 5:1, a minimum reflection loss value (RL) of −24.7 dB was achieved with a thickness of only 1.3 mm at a frequency of 14.4 GHz. Besides, when the thickness was reduced to 1.2 mm, the effective absorption bandwidth extended to 3.75 GHz. The results suggest that impedance matching and the synergistic effect of multiple loss mechanisms contribute to the excellent electromagnetic wave absorption performance of the materials. Consequently, the VS2/MWCNTs composites exhibit simple synthesis, wide absorption bandwidth, thin thickness, and high absorption capacity, rendering them a promising material for practical microwave absorption applications.

Construction of dielectric and magnetic coupling cobalt salt/chitosan derived Co/C hybrid aerogels for high-performance infrared/radar compatible applications

In virtue of mutually exclusive stealth mechanisms, effectively protecting from infrared detection and attenuating microwaves through composition and structure design remains a formidable challenge. To achieve high-efficiency infrared/radar compatible stealth, in this work, 0D magnetic Co nanoparticles were successfully in situ grown onto the renewable biomass chitosan-based 3D porous carbon skeletons via facile liquid reaction, freeze-drying, and calcination method. Herein, the as-prepared Co/C hybrid aerogels exhibit dielectric and magnetic coupling network, and the relevant infrared/radar compatible stealth property can be regulated by adjusting the addition amount of Co salt. The minimum thermal conductivity value reached 0.095 W m−1 K−1 at 60 °C, and the lowest infrared emissivity of 0.717 in the 8–14 μm band was also achieved. Furthermore, the minimum reflection loss (RLmin) value of −44.70 dB at a relatively thin thickness of 1.35 mm and the maximum effective absorption bandwidth (EAB) of 5.45 GHz at only 1.5 mm appeared in the optimal Co/C hybrid aerogel with the most appropriate Co content. Compared with perfect conductive layer (PEC), the simulated radar cross section (RCS) signals of Co/C composites covered PEC have been significantly reduced by 18.44 dB m2 at the scanning angle of 80°. This study inspires the exploration of the elaborate design strategy and facile construction method for environment-friendly infrared/radar compatible hybrid aerogels in the future.

Construction of polymer-derived double transition metal compound/carbon matrix nanocomposites for efficient electromagnetic wave absorber

As typical dielectric materials, transition metal compounds have a broad potential in the field of stealth, but their application is still hampered by poor conductivity. In this study, based on the mechanism of electrostatic self-assembly of heteropolyacids and organic ligands, the electrostatic structures obtained after the introduction of different heteropolyacids into the conductive phase pyrrole are carbonized. On the one hand, the as-prepared transition metal compounds/carbon matrix nanocomposites produce synergistic effects and optimize impedance matching, and on the other hand, the formation of the abundant heterogeneous interfaces as well as the doping of the N, P heteroatoms induce the generation of interfacial polarization and dipole polarization, all of which provide the opportunities to produce composites with enhanced electromagnetic wave absorption properties. Unsurprisingly, the best synthesised sample, Mo2C/W2C/NPC, exhibits a significantly improved electromagnetic wave absorption performance, with an effective bandwidth of 5.7 GHz at a matched thickness of 2.5 mm, where the minimum reflection loss value of -54.5 dB is also achieved. The total effective bandwidth of the Mo2C/W2C/NPC-35wt% is up to 10.5 GHz (7.3-17.8 GHz) via adjusting the matching thickness in the range of 1.7-3.5 mm. Therefore, this study reflects that dual transition metal compound/carbon based composite wave-absorbing materials provide a new material basis for the construction of high-performance absorption materials.

Low-frequency and broadband electromagnetic wave absorption mechanism of (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ/PyC microspheres with hierarchy pores from 4 GHz to 17 GHz

Achieving low-frequency broadband electromagnetic wave absorption in extreme environments over 2000 °C is challenging. Biomimetic hierarchy materials of high entropy lanthanide carbides were designed to optimize electromagnetic wave absorption. Composite microspheres of (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ and SiC embedded in pyrolytic carbon (MC/PyC) were prepared by using the electro-spray method followed by heat treatment. The specimens of MC/PyC microspheres with a thickness of 2.5 mm exhibited a minimum reflection loss value of − 48.9 dB, and electromagnetic wave absorption from 4.0 GHz to 17 GHz. The enhanced absorption capability is attributed to the synergistic effect of dielectric losses from conduction and polarization, along with magnetic losses due to eddy currents and natural resonance of the high-entropy carbides within the multiscale pores. The composition and featured microstructure MC/PyC microspheres were noteworthily stable under the 2200 °C oxyacetylene ablation, ensuring consistent high-performance electromagnetic wave absorption even in harsh conditions.