Stealth design for high-value targets is experiencing a research upsurge in response to increasingly advanced detection technologies, and the emerging metamaterials provide the unparalleled platforms to efficiently achieve stealth owing to their powerful manipulation capability for electromagnetic (EM) waves. Nevertheless, most existing broadband stealth metamaterials still suffer from the bottlenecks of large thickness, complex artificial design and difficult prototype fabrication, which immensely hinder their practical application. Herein, an inspiring strategy of the absorption-scattering synergy metamaterial (ASSM) with the thickness of 4 mm is proposed to fulfill broadband stealth based on absorption-scattering synergy mechanism. By virtue of the prepared composite material with excellent absorption capacity and the designed two meta-atoms with low reflection amplitudes and 1-bit reflection phases, the ASSM is rapidly optimized by the binary particle swarm optimization (BPSO) algorithm and precisely fabricated by the fused deposition modelling (FDM) 3D printing technology. Multitudinous simulations and experiments demonstrate that the proposed ASSM can realize broadband RCS reduction by more than 10 dB with the relative bandwidth exceeding 97.8%, and also possesses outstanding polarization insensitivity and angle stability. Given the merits of simple structure, small thickness, reconfigurable EM responses and rapid design and fabrication, our methodology has tremendous application potential in the stealth design of high-value targets.

Metasurfaces have attracted significant research attention due to their exceptional capabilities in manipulating electromagnetic (EM) waves, which have achieved a wide range of groundbreaking applications. Active metasurfaces represent an emerging class of reconfigurable platforms that can dynamically tailor functionalities in real-time, especially in radar cross section (RCS) modulation. Nevertheless, conventional designs for metasurfaces are not only difficult to conform to curved surface structures, but also suffer from narrow bandwidth and strong angular dependence, which tremendously limit their practical application. In this article, we propose a conformal active metasurface (CAM) that enables continuous and dynamic RCS modulation on curved targets. By strategically adjusting the bias voltages of regionally distributed p-i-n diodes to achieve adaptive impedance matching, the CAM can efficiently absorb EM waves across a broad frequency spectrum and a wide range of incident angles. Through theoretical analysis, optimal design, and experimental validation, we demonstrate that the proposed CAM achieves an average continuous dynamic RCS reduction of more than 10 dB, with a maximum reduction of 27 dB in simulation and 26 dB in measurement within 8-15 GHz, which is well maintained across an incident angle range of 0 degrees-50 degrees. This facilitates continuous and dynamic modulation of the target's RCS in adaptation to variations in the surrounding EM environment, allowing the target to merge seamlessly with conventional platforms in the reflection state, preventing the detection of anomalous scattering signatures, while enabling active stealth functionality in the absorption state. This work provides a feasible strategy for designing highly adaptable, broadband, and wide-angle CAMs, with strong potential for applications in radar stealth, wireless communications, and integrated sensing systems.

Y2O3-modified NbTiVZr-ZrC-SiC composite coatings were fabricated on C/C composites by atmospheric plasma spraying to construct a refractory high-entropy alloy/ultra-high-temperature ceramic hybrid protective coating with tunable ceramic content and SiC/ZrC mass ratios. After oxyacetylene ablation at a heat flux of 2.4 MW·m−2 for 60 s, the optimized coating containing 80 wt% NbTiVZr, 6.7 wt% SiC, 12.7 wt% ZrC, and 0.6 wt% Y2O3 exhibited a mass ablation rate of 2.23 mg·s−1 and a linear ablation rate of −1.39 μm·s−1. The improved ablation resistance is attributed to the phase evolution of ZrC, SiC, Y2O3 and the NbTiVZr high-entropy alloy matrix during ablation, which leads to the formation of a dense oxide structure. The oxidation of ZrC contributes to the formation of a zirconia-based refractory skeleton, while the SiO2-rich phase derived from SiC flows into the oxide layer and favors the sealing of pores and microcracks. Meanwhile, Y2O3-assisted stabilization promotes the formation of the YSZ phase and mitigates the tetragonal-to-monoclinic transformation of ZrO2. The resulting TiNb2O7 and Nb2Zr6O17 multicomponent oxides further improve the cohesion and stability of the protective scale, maintaining the integrity of the ablation layer and reducing oxygen penetration into the coating/substrate system.

3D metastructures offer compelling potential for high-performance electromagnetic (EM) wave absorption, yet their inability to concurrently deliver robust mechanical load-bearing capacity and enclosed structural integrity hinders their direct application in radar absorbing mobility platforms. Herein, we propose a novel multifunctional hybrid metastructure based on continuous fiber reinforcement (MHMCF) that serves as a seamlessly integrated component. By leveraging the complementary EM and mechanical properties of continuous glass fibers and carbon fibers within an optimized sandwich architecture, the design enables concurrent EM absorption and structural robustness. Co-optimized via a non-dominated sorting genetic algorithm, this design maximizes EM absorption bandwidth and attenuation strength. The broadband EM response is systematically explored through component variation and parametric tuning, elucidating the EM wave absorption mechanism through impedance matching and field distribution analysis. Crucially, MHMCF achieves single-step fabrication through multimaterial 3D printing, eliminating post-assembly. Our results demonstrate that the continuous fibers enhance the EM loss and load-bearing characteristics, leading to exceptional broadband and wide-angle EM wave absorption (2-18 GHz, 0-75 degrees), high bending strength (44 MPa), and large flexural modulus (2882 MPa). This work establishes a new designing paradigm for panel-integrated metastructures, offering a viable strategy to achieve concurrent EM stealth and structural robustness in next-generation aerospace systems via multi-material synergy and architectural optimization.

Dynamic spectral regulation facilitates the manipulation of light across various wavelength bands, leveraging distinct optical properties to enable diverse functionalities and behaviors. Precise control of solar and thermal radiation offers novel pathways for heat flow manipulation, with promising applications in energy-efficient buildings, camouflage, and aerospace technologies. Reversible metal electrodeposition (RMED) technology, through its electrochromic properties, allows flexible control of light transmission behavior, demonstrating significant potential for advanced thermal regulation. However, a comprehensive review focusing on the effects of different modification methods on optical and electrochemical performances, as well as systematic analysis of the applications and mechanisms of RMED, remains lacking. Herein, this review first demonstrates the fundamental electrochemical and optical regulation principles of RMED, elucidating the underlying physico-chemical mechanisms and discussing performance evaluation methods. Then, the modification strategies for devices operating in different wavelength bands and based on different metal systems are discussed and compared. Finally, the review presents feasible strategy for addressing the current main challenges and discusses future research directions. This review aims to guide future improvement of device performance in terms of cycle stability, open-circuit stability, response rate, and spectral modulation range.

With the rapid development of electronic information and military stealth technologies, electromagnetic interference and pollution have become increasingly critical, creating an urgent need for nextgeneration high-performance microwave absorbers. However, conventional carbon-based absorbers exhibit limited loss mechanisms, while magnetic metal nanoparticles suffer from agglomeration, oxidation, and high density. To overcome these limitations, an ultrafast synthesis strategy assisted by urea gas expansion and Joule heating is proposed. Gas expansion induced by urea pyrolysis ensures the homogeneous dispersion of CoFe alloy precursors within the phenolic resin matrix. Subsequently, the instantaneous high temperature generated by Joule heating enables rapid nucleation, leading to the formation of uniformly distributed CoFe nanocrystals with strong interfacial coupling to the porous carbon matrix (CF-C). The CF-C composite achieves full absorption in the $\mathbf{X}$ band, offering a promising route toward high-performance microwave absorbers.

Flexible metastructure absorbers combine the advantages of conventional metastructures with the conformal architectures, unlocking potential electromagnetic (EM) applications. In this work, we tackled broadband EM enhancement of metastructures via strategic material engineering and unit cell optimization. Herein, a multilayer metastructure was designed using bioinspired architectures and intelligent optimization techniques. The interlocking mechanism of armadillo scales and the anti-reflective property of moth-eye structures were the inspiration for the metastructure design, which simultaneously achieved exceptional conformal adaptability and broadband impedance matching. The structural parameters were co-optimized through a hybrid algorithm that integrates the Grey Wolf Optimizer with manta ray foraging optimization, enabling maximized absorption bandwidth and minimized reflectivity. Fabricated via fused deposition modeling 3D printing, the optimized metastructure demonstrates remarkable EM absorption performance, delivering over 90

Sustainable dielectric relaxation across a broad temperature window remains a significant challenge for high-temperature electromagnetic-wave (EMW) absorption, particularly in extreme conditions where dissipation pathways are severely constrained. Herein, a porous ceramic embedded with high-entropy nanocrystals (P-HEN) was developed by leveraging the confinement effect of the SiOCN covalent network. The confined growth and effective phase separation of (FeNiCoAl)3O4 nanocrystals generate thermally stable dielectric-relaxation activation units within the SiOCN matrix. Furthermore, the random distribution of multi-metal cations in the nanocrystals, together with the multi-interfacial interactions between the nanocrystals and the matrix, generates strong polarization responses. Consequently, P-HEN achieves sustained dielectric relaxation and full-band effective absorption in the X-band over a wide temperature range from 25 to 700 degrees C, while also exhibiting excellent thermal insulation and ablation resistance. This work demonstrates a confinement-enabled mechanism for stabilizing dielectric-relaxation loss at elevated temperatures, providing a new strategy for designing wide-temperature-window EMW absorbers.

As two-dimensional metamaterials, metasurfaces have attracted considerable research interest owing to their advantages of small volume and simple fabrication. By integrating the metasurfaces with active components controlled by electric bias, active metasurfaces are able to dynamically manipulate electromagnetic (EM) waves and realize innovative applications across diverse fields. However, conventional active metasurfaces are difficult to achieve continuous and dynamic control of absorptivity and reflectivity over a wide frequency band, which immensely restricts their application in weapon stealth and camouflage. This study presents what we believe to be a novel design that employs an absorbing active metasurface (AAM) to continuously and dynamically control the reflection amplitude, which is achieved by flexibly controlling the external voltage of PIN diodes across multiple layers. The experimental results demonstrate that the proposed AAM can achieve continuous and dynamic amplitude modulation within the frequency range of 2.0-15.5 GHz at normal incidence, and maintain angular insensitivity within the incidence angle range of 0°-50°. This inspiring design not only has excellent dynamic control capabilities for EM waves absorption and reflection, but also possesses the advantages of simple design, small thickness and easy fabrication, which has tremendous application potential in stealth weapons and other smart metadevices.

Electronic modulation for balancing oxygen intermediates bending energy over oxygen evolution catalytic active sites is one of the most critical factors but still remains challenging. In this case, yolk-shell Co8FeS8-FexCy was constructed by fast Joule-heating process with dual-ligand PBA as precursor. With the help of Spherical aberration corrected STEM, synchrotron-radiation photoelectron spectroscopy as well as DFT calculations, the consecutive manipulation of d-band center for the designed series of Co8FeS8-based samples by introducing the FexCy with varying element ratios was disclosed. The findings confirm that electron modulation of Co8FeS8-FexCy can upshift the d-band center toward Fermi level to optimize antibonding-orbital occupancy of the metal-O bond, thereby prominently minimizing Gibbs free energy for intermediates in the rate-determining step. Encouragingly, the optimal Co8FeS8-Fe7C3 delivers a significant overpotential (eta 10) decrease by 118 mV compared with Co8FeS8-C, ultrasmall Tafel slope of 33.4 mV dec-1, along with excellent catalytic durability. Furthermore, it also shows enhanced electromagnetic wave dissipation ability with the minimum reflection loss of -50.72 at 2.03 mm and effective absorption bandwidth of 7.87 GHz at 1.7 mm. This work uncovered the intrinsic regulation mechanism of microcomponent design and opens up a promising prospect for exploring advanced multifunctional materials.

Multispectral camouflage faces growing urgency due to multimodal detection threats. To meet the spectral requirements for different bands, artificially designed selective spectral properties are needed. However, achieving a balance among simplicity of configuration, durability, spectral selectivity, and large-scale potential remains challenging, as well as achieving passive radiative cooling for effective thermal management. Here, we present a Ge (635 nm)/ZnS (1152 nm)/Ge (1260 nm)/ZnS (1141 nm)/Ge (656 nm) heterogeneous photonic crystal (HPC) selective thermal emitter for achieving low thermal emissivity camouflage (epsilon 3-5 = 0.28, epsilon 8-14 = 0.24), low laser reflection at 10.6 mu m (0.29), and radiative cooling within non-atmospheric window (0.70 at Cu films at 350 degrees C. The emitter also has good angle and polarization independence, environmental durability, and can be manufactured on a large scale. This technology offers a costfor combining camouflage with thermal management.

Vortex beams carrying orbital angular momentum (OAM) have become a cutting-edge solution for advanced radar scanning and OAM multiplexing communication systems due to their unique phase singularity and modal orthogonality. Metasurfaces have been established as a high-efficiency and miniaturized platform for the generation of OAM vortex beams. However, most existing state-of-the-art OAM-generating metasurfaces adopt planar structures, which suffer from inferior conformal compatibility and cannot be integrated with curved aerodynamic components and radome platforms in practical engineering applications. Furthermore, conventional passive vortex metasurfaces merely produce fixed OAM modes with narrow operating bandwidths, lacking the capacities of dynamic mode reconfiguration and multi-angle beam scanning. To address these technical limitations, this paper proposes a curved conformal active metasurface loaded with tunable functional devices. The elaborately designed structure achieves flexible dynamic switching of multiple OAM topological charges l=±1, ±2, ±3 and realizes multi-directional vortex beam scanning within the reflection angle range of 0°–30°. Numerical simulation results verify that the proposed metasurface can generate high-purity and stable vortex beams over a broadband frequency range of 9.3–10.5 GHz, with the maximum pointing error of multi-angle beam scanning restricted within ±2°. Benefiting from the rationally optimized conformal configuration, no obvious degradation in electromagnetic performance occurs after structural conformal deformation. The proposed design effectively circumvents the inherent drawbacks of conventional planar and passive vortex metasurfaces, offering a viable technical scheme for the design and engineering implementation of conformal vortex beam antennas and curved radome-integrated radar systems.

Carbon-based absorbing agents are extensively utilized in electromagnetic wave absorption due to their low density and high electrical conductivity. However, the elevated electrical conductivity of carbon materials creates a mismatch between electrical conductivity and polarization loss, complicating the attainment of lightweight and broad-spectrum wave absorption. In this study, we synthesized a type of N-doped carbon nanosheet featuring a porous structure through a one-step doping-activation synergistic pyrolysis process. Nitrogen doping enhances the material's polarization loss capacity by modulating the distribution of heterogeneous charges and forming localized centers within the matrix. The porous carbon nanosheets provide abundant conductive pathways, heterogeneous interfaces, and internal cavities, which can expand the absorption frequency band while maintaining a lightweight profile. Additionally, the conductivity and polarization loss are fine-tuned by adjusting the doping structure and concentration of nitrogen elements. The final absorbent content is merely 3wt%, yielding a reflection loss as low as -61.15dB and an effective absorption frequency band of 7.40GHz. Compared to traditional carbon materials, the absorption performance of this nanosheet has been significantly enhanced. Overall, this study presents a novel approach for the preparation of nitrogen-doped carbon absorbers and establishes a foundation for the design and optimization of broadband electromagnetic wave absorbers.

Phenolic resin materials have a wide range of applications in aerospace thermal protection due to their excellent thermal stability， as well as their low cost and short preparation cycle. By means of chemical and physical modification， more functions or new features can be integrated into phenolic resin matrix composites to make them develop in the direction of high performance and further broaden their application areas. In this paper， the research progress of heat-resistant modification of phenolic resin matrix composites in recent years is reviewed in detail， and the modification methods for synthetic raw materials， molecular structure， and pyrolytic morphology are discussed from the thermal decomposition mechanism. The application prospects are elaborated， and the current problems are analyzed in depth， such as the performance needs in extreme environments still need to be further improved， and the development direction of the high performance and multifunctionality of phenolic resin matrix composites is proposed， and the development direction of further improving its serviceability is discussed. The development direction of high performance and multifunctionalization of phenolic resin matrix composites is proposed， which is of great significance for further improving its service performance and expanding its application scope.

The new active metasurface has the advantages of small size, lightweight and easy integration, so it has an important application prospect in weapon radar intelligent stealth. Based on this, focusing on the requirements of radar intelligent stealth for current weapons and equipment, this paper expounds the methods, approaches and performance advantages of active metasurface in electromagnetic wave regulation, reviews the development history of various active metasurface, and summarizes the research status and future development direction of active metasurface for radar intelli- gent stealth. It provides the relevant theoretical basis and design reference for the wide application of active metasurface in intelligent stealth of weapon equipment radar.

The pi-pi interactions in the sp2-C surfaces result in low electronic activity, necessitating the functionalization of CNTs to reduce surface energy and form carbon-based composites. However, current efforts to improve the electromagnetic wave absorption performance of carbon-based composites have largely focused on composite design, overlooking the changes in the intrinsic electromagnetic properties of CNTs after functionalization. Herein, three commonly used functionalized CNTs were designed and synthesized, and their kinetic processes and changes in electromagnetic wave dissipation mechanisms were systematically investigated. The results show that the functionalization of CNTs disrupts their original pi-conjugated system; although dipolar polarization effects are introduced, their charge transport capability is significantly reduced, leading to a decrease in conductive losses. Furthermore, the disruption of electron transport pathways has a more pronounced impact on electromagnetic wave absorption performance, becoming a key factor influencing the overall electromagnetic wave absorption effectiveness. These findings provide important guidance for the design of novel carbon-based electromagnetic wave absorption materials. During composite design, in addition to incorporating other absorption mechanisms, particular attention should be paid to the repair of electron transport pathways to ensure excellent electromagnetic wave absorption performance.

To address the issue of reduced ablation resistance in C/C composites due to poor oxidation resistance at high temperatures, a NbTiVZr refractory high-entropy alloy coating was fabricated on the surface of C/C composites by atmospheric plasma spraying technology. The influence of plasma enthalpy during plasma spraying on the phase composition, microstructural evolution, and ablation behavior of the coating was systematically investigated. It was shown by the results that increasing plasma enthalpy promoted the transition of the coating from a multiphase mechanical mixture to a predominantly body-centered cubic solid solution matrix, but excessive enthalpy also reduced structural compliance and induced segmentation cracking. The coating achieved a balance between structure and performance at the enthalpy value corresponding to a current of 600 A. It remains structurally intact after being tested in a 2100 degrees C oxyacetylene flame for 20 s with a mass ablation rate of-0.833 mg/s. A 3D spatial protection mechanism is proposed. Structurally, the BCC phase and optimized porosity synergize to provide multiscale strain tolerance. Thermochemically, a rigid ZrO2 skeleton resists erosion, integrated by a Nb2Zr6O17 matrix, while a viscous TiNb2O7 liquid aided by V-oxide outgassing dynamically seals defects. It was indicated by these results that achieving synergy between structural compliance and phase evolution is prioritized over maximizing solid-solution purity.

Multispectral compatible stealth of high-value targets has intrigued long-standing interest in response to the rapid development of multispectral detection technologies, and a series of ingenious metasurfaces profiting from the exotic electromagnetic (EM) property has provided exceptional platforms for realizing multispectral compatible stealth. Nevertheless, most existing multispectral compatible stealth metasurfaces still suffer from the drawback of immutable stealth performance, which tremendously hinders their practical application in various complex scenarios. Herein, an inspiring strategy of the programmable coding metasurface (PCM) with a thickness of approximately 0.1 λ 0 is proposed to fulfill dynamic microwave manipulation, low infrared radiation, and high optical transparency. Owing to continuous amplitude dynamic modulation and 1-bit phase dynamic modulation implemented by adjusting the PIN diodes of well-designed meta-atoms, the proposed PCM is capable of independently and dynamically controlling the absorption intensity and scattering direction of EM waves in broad bandwidth. Simultaneously, the average infrared emissivity of the PCM can be reduced to about 0.25 from 3 to 14 μm, attributed to the low infrared radiation of the surface indium-tin-oxide (ITO) structures, and the optical transparency can reach 65.9% at 565 nm due to the design of the copper mesh structure and the selection of the transparent dielectric substrate. Multitudinous simulations and experiments of the proof-of-concept prototype are in accordance with theoretical predictions and corroborate the effectiveness of our methodology. This remarkable paradigm of the PCM shows unprecedented intelligence and integration in multispectral compatible stealth and may also find potential applications in communication, imaging, and other intelligent metadevices.

With advancements in radar detection and electromagnetic (EM) communication technologies, intelligentizing EM functional materials (EFMs) and endowing them with dynamic responsiveness across multi-spectral ranges, along with the ability to perceive and adapt to complex operation environments, is of significant importance. This article provides a comprehensive review of the recent progress in intelligent EFMs. It begins with the fundamentals of intelligent EFMs, with an emphasis on their EM response mechanisms and basic functions. The motivation and necessity of developing intelligent EFMs are then discussed. Thereafter, new advances, particularly in the design of intelligent EFMs for various applications, including EM communication systems, EM protection platforms, sensors, robots, energy harvesting devices, wearable electronics, healthcare, and environmental management, are highlighted. Lastly, this review concludes with an outlook on future directions, critical challenges to address, and possible solutions for intelligent EFMs.

Conventional metastructures encounter limitations in simultaneously achieving broadband performance, thin thickness, and adaptability to curved surfaces. To overcome these challenges, a chessboard-like metastructure was developed based on a dual complementary mechanism of electromagnetic (EM) absorption and phase interference, aimed at enhancing its radar cross section (RCS) reduction performance. Through the design of multi-scale unit cells and optimized spatial arrangement, a - 10 dB RCS reduction bandwidth spanning 5.3 similar to 18 GHz was achieved. Notably, the propagation phase compensation model was introduced to ensure stable performance under extreme curvature (alpha=180 degrees) and wide-angle incidence (0 degrees similar to 60 degrees), surpassing existing conformal metastructures in bandwidth efficiency. The influence of unit cell parameters on RCS reduction was systematically investigated and validated through simulations and experimental measurements. This work offers a viable approach for the design of lightweight, ultra-thin metastructures with strong potential for conformal EM stealth applications.