Synergistically Assembled Cobalt-Telluride/Graphene Foam with High-Performance Electromagnetic Wave Absorption in Both Gigahertz and Terahertz Band Ranges

Activating Basal Plane Inert Sites of Iron Telluride for Motivational Electromagnetic Microwave Absorption

The basal plane inert sites and inadequate intrinsic dielectric relaxation are the major bottlenecks limiting the electromagnetic microwave (EMW) absorption performance of transition metal tellurides (TMTs). Here, an effective dual defect model based on electron polarization relaxation is established on iron telluride (FeTe) flakes via one-step O2 plasma treatment. Therefore, the basal plane inert sites of FeTe are activated by Te vacancies and O incorporation, which form abundant polarization centers, resulting in charge redistribution and increased dipole site density, thereby effectively optimizing dielectric relaxation loss. Consequently, the optimal EMW attenuation performance achieves a minimum reflection loss exceeding -69.6 dB at a thickness of 2.2 mm, with an absorption bandwidth of up to 4.9 GHz at a thickness of 1.3 mm. Besides, FeTe with dual defect exhibits a prominent radar cross-section reduction of 42 dBsm, indicating excellent radar wave attenuation capability. This study illustrates an innovative model system for elucidating dielectric relaxation loss mechanisms and provides a feasible approach to developing high-loss TMTs-based absorbers.

Multifunctional microwave absorption materials: construction strategies and functional applications

The widespread adoption of wireless communication technology, especially with the introduction of artificial intelligence and the Internet of Things, has greatly improved our quality of life. However, this progress has led to increased electromagnetic (EM) interference and pollution issues. The development of advanced microwave absorbing materials (MAMs) is one of the most feasible solutions to solve these problems, and has therefore received widespread attention. However, MAMs still face many limitations in practical applications and are not yet widely used. This paper presents a comprehensive review of the current status and future prospects of MAMs, and identifies the various challenges from practical application scenarios. Furthermore, strategies and principles for the construction of multifunctional MAMs are discussed in order to address the possible problems that are faced. This article also presents the potential applications of MAMs in other fields including environmental science, energy conversion, and medicine. Finally, an analysis of the potential outcomes and future challenges of multifunctional MAMs are presented.

Flexible Terahertz Broadband Absorber Based on a Copper Composite Film

Terahertz absorbers play a crucial role in terahertz detectors, radar stealth, electromagnetic shielding, and other fields. However, the design and fabrication of flexible terahertz broadband absorbers remain a challenge at present. Here, we demonstrated a terahertz broadband absorber based on a copper composite film (CCF) consisting of a copper foam and an organic silica gel doped with Fe3O4 powder. The CCF can be fabricated by the infiltration method. The influence of the thickness and the pore size of the copper foam and the mass fraction of doped Fe3O4 powder on the absorption bandwidth were investigated. When the thickness of the CCF is 1.5 mm, the pore size of the copper foam is 95 pores per inch (ppi), and the mass fraction of Fe3O4 is 1%; a broadband absorption is achieved in the range of 0.11-3.5 THz. It is noted that the mass fraction of Fe3O4 has a significant impact on the absorption bandwidth. In addition, the thickness of the CCF and the pore size of the copper foam also have an impact on the absorption. The impedance matching theory is introduced to understand the mechanism of broadband absorption. This flexible broadband absorber has potential application in terahertz stealth, shielding, and the sixth-generation (6G) broadband wireless communication in the future.

Coral-Inspired Terahertz-Infrared Bi-Stealth Electronic Skin

The development of electronic skin with dual stealth functionality is crucial for enabling devices to operate effectively in dynamic electromagnetic environments, thereby facilitating intelligent electromagnetic protection for autonomous perception. However, achieving compatibility between terahertz (THz) and infrared (IR) stealth technologies remains largely unexplored due to their inherent contradictions. Herein, inspired by natural corals, a novel coral-like multi-scale composite foam (CMSF) was proposed that ingeniously reconciles these contradictions. The design capitalizes on the conductive network and heat insulation properties of the foam skeleton, the loss effects and low infrared emission of metal particles, and the infrared transparency of magneto-optical materials. This approach leads to the realization of a THz-IR bi-stealth electronic skin concept. The CMSF exhibits a maximum reflection loss of 84.8 dB in the terahertz band, while its infrared stealth capability ensures environmental adaptability under varying temperatures. Furthermore, the electronic skin exhibits exceptional sensitivity and reliability as a wearable device for perceiving environmental changes. This advanced material, combining multispectral stealth with sensing capabilities, holds immense potential for applications ranging from camouflage technology to smart wearables.

Rapid microwave-assisted synthesis and characterization of a novel CuCoTe nanocomposite material for optoelectronic and dielectric applications

In the realm of nanomaterial research, copper telluride and cobalt telluride have individually attracted considerable attention owing to their unique properties and potential applications. However, there exists a notable gap in the literature when it comes to the exploration of composite materials derived from these elements. From this point of view, a ternary CuCoTe nanocomposite was prepared using the microwave synthesis method. Various characterizations were performed by varying the power and irradiation time. X-Ray diffraction study and transmission electron microscopy analysis confirmed the polycrystalline nature of the material with Cu2Te and CoTe hexagonal phases. Field emission scanning electron microscopy images reveal nanoparticle-like morphology, which remains unchanged even when the time of irradiation increases. In addition, the nanoparticle size of the material lies in the range of 30-39 nm. The differential scanning calorimetry inferred various exothermic and endothermic peaks. Meanwhile, the optical analysis from the UV-visible study shows the red-shifted absorbance, enabling the material for semiconductor and photovoltaic devices. Furthermore, the optical bandgap of the material varies in the range from 2.45 to 3.61 eV, which reveals the tuneable bandgap desiring the material for various optoelectronic applications. The frequency-temperature-dependent dielectric study gives results for dielectric parameters, conductivity, and impedance behaviour. The material's dielectric constant, dielectric loss, and AC conductivity enhance with the increase in temperature. This behaviour of the material broadens the area of applicability in energy storage devices.

High-Quality Ferromagnet Fe3GeTe2 for High-Efficiency Electromagnetic Wave Absorption and Shielding with Wideband Radar Cross Section Reduction

A high-quality Fe₃GeTe₂ single crystal with good electrical, magnetic, and electromagnetic wave absorption and shielding properties was prepared in a large quantity (10 g level) by solid-phase sintering and recrystallization method, which would promote its in-depth research and practical application. It has good room-temperature electrical properties with a mobility of 42 cm²/V·s, a sheet (bulk) carrier concentration of +1.64 × 10¹⁸ /cm² (+3.28 × 10²⁰ /cm³), and a conductivity of 2196.35 S/cm. Also, a Curie temperature of 238 K indicates the high magnetic transition temperature and a paramagnetic Curie temperature of 301 K shows the large ferromagnetic-paramagnetic transition zone induced by the residual short-range ferromagnetic domains. Particularly, Fe₃GeTe₂ is in a loosely packed state when used as a loss agent; the electromagnetic wave absorption with a reflection loss of -34.7 dB at 3.66 GHz under thin thickness was shown. Meanwhile, the absorption band can be effectively regulated by varying the thickness. Moreover, Fe₃GeTe₂ in a close-packed state exhibits terahertz shielding values of 75.1 and 103.2 dB at very thin thicknesses of 70 and 380 μm, and the average shielding value is higher than 47 dB, covering the entire bandwidth from 0.1 to 3.0 THz. Furthermore, by using Fe₃GeTe₂ as a patch, the wideband radar cross-section can be effectively reduced by up to 33 dBsm. Resultantly, Fe₃GeTe₂ will be a promising candidate in the electromagnetic protection field.

Corrosion-Resistant Graphene-Based Magnetic Composite Foams for Efficient Electromagnetic Absorption

Designing and fabricating high-performance microwave absorption materials with efficient electromagnetic absorption and corrosion resistance becomes a serious and urgent concern. Herein, novel corrosion-resistant graphene-based carbon-coated iron (Fe@C) magnetic composite foam is fabricated via self-assembly of iron phthalocyanine/Fe₃O₄ (FePc hybrid) on the graphene skeletons under solvothermal conditions and then annealing at high temperature. As a result, the rational construction of a hierarchical impedance gradient between graphene skeletons and Fe@C particles can facilitate the optimization in impedance matching and attenuation characteristic of the foam, realizing the efficient dissipation for incident electromagnetic waves. Additionally, the performance of electromagnetic absorption can be controllably regulated by optimizing annealing temperature and/or time. More importantly, the formation of a carbon-coated iron structure substantially improves the corrosion resistance of magnetic particles, endowing the composite foam with excellent stability and durability in microwave absorption performance.

Interfacial π-π Interactions Induced Ultralight, 300 °C-Stable, Wideband Graphene/Polyaramid Foam for Electromagnetic Wave Absorption in Both Gigahertz and Terahertz Bands

High-performance electromagnetic wave-absorbing (EMA) materials used in high-temperature environments are of great importance in both civil and military fields. Herein, we have developed the ultralight graphene/polyaramid composite foam for wideband electromagnetic wave absorption in both gigahertz and terahertz bands, with a higher service temperature of 300 °C. It is found that strong interfacial π-π interactions are spontaneously constructed between graphene and polyaramids (PA), during the foam preparation process. This endows the foam with two advantages for its EMA performance. First, the π-π interactions trigger the interfacial polarization for enhanced microwave dissipation, as confirmed by the experimental and simulation results. The composite foam with an ultralow density (0.0038 g/cm³) shows a minimum reflection loss (RL) of -36.5 dB and an effective absorption bandwidth (EAB) of 8.4 GHz between 2 and 18 GHz band. Meanwhile, excellent terahertz (THz) absorption is also achieved, with EAB covering the entire 0.2-1.6 THz range. Second, the interfacial π-π interactions promote PA to present a unique in-plane orientation configuration along the graphene surface, thus making PA the effective antioxidation barrier layer for graphene at high temperatures. The EMA performance of the foam could be completely preserved after 300 °C treatment in air atmosphere. Furthermore, the composite foam exhibits multifunctions, including good compressive, thermal insulating, and flame-retardant properties. We believe that this study could provide useful guidance for the design of next-generation EMA materials used in harsh environments.

High Performance Microwave Absorption of Lightweight and Porous Non-carbon-based Polymeric Monoliths via Gel Emulsion Template

A special porous non-carbon-based microwave-absorbing materials are designed and synthesized by bonding di(prop-1-en-2-yl) ferrocene into porous polymeric monoliths made by gel-emulsions as templates. In this study, a sequence of porous...

Construction of MOF-derived plum-like NiCo@C composite with enhanced multi-polarization for high-efficiency microwave absorption

Nowadays, facing the inevitable electromagnetic (EM) pollution caused by many electronic products, it is urgent to develop high-performance microwave absorbing materials. In particular, the bimetallic carbon-based composites derived from MOFs exhibit excellent microwave absorption potential due to their simple preparation, low cost, adjustable morphology and magnetoelectric synergy mechanism. In this work, we successfully prepared plum-like NiCo@C composite by simple solvothermal method and carbonization treatment, which displays strong absorption (-55.4 dB) and wide effective absorption band (EAB, 7.2 GHz) when the loading is 20 wt%. The plum-like structure greatly enriches the non-uniform interface and the structural anisotropy contributes to the dissipation of electromagnetic waves. At the same time, the band hybridization and magnetic coupling of NiCo@C contribute to the coordination of EM characteristics. Overall, this work proves the feasibility of NiCo@C hierarchical composite in the field of microwave absorbing, and provides insight for the development of high-performance absorbers.