Minimum Reflection Loss Research Articles

Facile synthesis and microwave absorption capabilities of hierarchical porous BN@C composites

With the rapid advancement of electronic information technology, the issue of electromagnetic radiation has become increasingly severe. It is urgent to develop high efficiency microwave absorber with excellent microwave absorbing performance. The construction of complex and diversified hierarchical porous structure is regarded as a promising way to enhance electromagnetic wave absorption. In this study, leveraging the porous architecture of melamine foam, a BN@C composite material featuring a hierarchical pore structure comprising larger and smaller pores, both residing in the micrometer regime, was synthesized via a high-temperature-assisted sol-gel method, using polyvinyl alcohol as the carbon precursor and boron nitride (BN) as the filler. By optimizing the molar ratio of raw materials, BN@C composites exhibiting superior microwave absorption performance were successfully obtained. When the matching thickness was set at 2.5mm and 1.5mm, respectively, the minimum reflection loss (RLmin) reached -29.12dB, and the maximum effective absorption bandwidth (EAB) was 5.44GHz, demonstrating a broad application prospect in the realm of microwave absorption. This research not only provides novel insights into enhancing the microwave absorption capabilities of carbon-based materials but also lays a material foundation for the development of electromagnetic radiation protection and stealth technologies.

Simple preparation of high-temperature resistant BN-coated BCN fiber with a porous surface to enhance microwave absorption

Addressing this issue has become a significant concern in current research to enhance the performance and thermal stability of carbon electromagnetic wave (EMW) absorption materials. This study synthesizes BN-coated BCN fibers through wet spinning and precursor pyrolysis routes. A porous structure is incorporated between the BN and BCN fiber substrates to enhance EMW absorption performance. The results show that the BN-coated BCN fibers with a porous surface exhibit superior EMW absorption performance with the minimum reflection loss (RLmin) of -46.79 dB and the effective absorption bandwidth (EAB) of 5.5 GHz at 2mm, almost covering the Ku band. This straightforward co-doping and cost-effective synthesis strategy offers a novel design approach for preparing EMW absorption materials.

Mesoporous MXene nanosheets/CNF composite aerogels for electromagnetic wave absorption and multifunctional response

To acquire excellent wave-absorbing materials with broadened applications, transition metal carbides (Ti3C2Tx, MXene) have been the research focus. However, the high conductivity of MXene limits its electromagnetic wave (EMW) absorption capability; meanwhile, the inferior mechanical properties of MXene-based aerogels severely restrict their applications. Here, porous MXene (PMXene) nanosheets were prepared by hydrogen peroxide etching, which was then physically and chemically crosslinked with cellulose nanofibres (CNF) to successfully prepare PMXene/CNF composite wave-absorbing aerogels with excellent mechanical properties. PMXene/CNF aerogel achieved a minimum reflection loss (RLmin) of − 72.27 dB and an effective absorption bandwidth (EAB) of 5 GHz at a thickness of 1.63 mm without any magnetic component. The aerogels exhibited excellent environmental stability at a density of 12.5 mg/cm3, including fatigue resistance (100 compression cycles, 0.075 energy loss efficiency) and low-temperature resistance. Refining the mechanical properties exploits the aerogel’s potential for motion monitoring and electronic skin applications. In addition, the aerogels integrate properties such as water–oil separation, photothermal conversion, and thermal insulation (thermal conductivity of 0.045 W/(m-K)). Therefore, multifunctional PMXene/CNF aerogels have a broad potential for future application in the defence industry, electronic devices, and smart wearable fields.

Lightweight, thermally insulating SiBCN/Al2O3 ceramic aerogel with enhanced high-temperature resistance and electromagnetic wave absorption performance

Owing to tunable dielectric properties, light weight and high porosity, polymer-derived SiBCN ceramic aerogels possess significant application prospects in electromagnetic wave (EMW) absorption and thermal insulation. However, due to inadequate oxidation resistance, the structural collapse and performance deterioration of SiBCN aerogels will easily occur in high-temperature aerobic environments, limiting their application. Herein, to address this issue, a novel and straightforward strategy based on typical polymer-derived-ceramic (PDC) aerogel method and impregnation with boehmite sol was proposed for synthesizing SiBCN/Al2O3 composite ceramic aerogels. The microstructure, phase composition, thermal insulation, oxidation resistance and EMW absorption properties of SiBCN/Al2O3 ceramic aerogels were investigated. The resulting SiBCN/Al2O3 composite aerogel demonstrates superior high-temperature structural stability, exhibiting an ultra-low linear shrinkage of only 6.5 % following heat treatment at 1200 °C for 2 h in air. Additionally, the composite aerogel shows a low thermal conductivity of 0.039 W/mK and a low density of 0.112 g/cm3. The SiBCN/Al2O3 composite aerogel, composed of dielectric SiBCN, conductive free carbon, and insulating alumina, demonstrates outstanding EMW absorption properties with a minimum reflection loss of −48.6 dB and an effective bandwidth of 5.8 GHz. The enhanced microwave absorption performance is mainly attributed to the improved impedance matching, multiple reflection, and enhanced interfacial polarization resulting from the introduction of Al2O3. Given prominent oxidation resistance, thermal insulation and EMW absorption properties, the SiBCN/Al2O3 composite aerogel paves the way for developing microwave absorption and thermal insulation integrated material in high-speed vehicles.

MXene@Wood composite with absorption-dominated electromagnetic interference shielding performance through structural modification

Wood-based materials possess unique porous structure that are sustainable and green, showing great potential in many applications. Herein, MXene@Wood composites were prepared for electromagnetic interference shielding and thermal insulation, and their pore structure is monitored by compression of wood. Benefiting from the heterogeneous interface between MXene and the wood surface to enhance interfacial polarization, MXene@Wood presents a superior impedance match in cross-section compared to tangential-section. In the cross-section, MXene@Wood at a 30 % compression ratio achieves an absorption coefficient of 0.73 and a shielding effectiveness of 41.78 dB. After a 30 % compression ratio, MXene@Wood in cross-section achieves an absorption coefficient of 0.73 and a shielding effectiveness of 41.78 dB, it also exhibits wave absorption performance with a minimum reflection loss of −15.11 dB at 2 mm, meeting the commercial requirements. The effect of the pore structure of wood on shielding performance is further verified by finite element analysis. Furthermore, MXene@Wood also demonstrates excellent thermal insulation properties benefit to the reduced gas-phase heat transfer. This sustainable composite with electromagnetic shielding performance and thermal insulation properties largely expands the application area of wood.

Lightweight dielectric-magnetic synergistic necklace-shaped Co@NCP/carbon nanofiber composites for enhanced electromagnetic wave absorption

In order to solve the problem of impedance mismatch of carbon fiber absorbing materials, it is crucial to create a carbon-based absorbing material with a special structure, synergistic magnetic and dielectric properties. In this paper, necklace-shaped Co@N-doped carbon polyhedron /carbon nanofiber (Co@NCP/CNF) composites with synergistic magnetic and dielectric properties are successfully fabricated by electrospinning. Compared with Co@NCP and CNF, the optimal minimum reflection loss of Co@NCP/CNF composite is -66.14 dB at 2.89 mm and the maximum effective absorption bandwidth is 6.24 GHz (11.76-18.00 GHz) at 2.25 mm at a low filler load of 10 wt.%. The necklace-like structure, the coupling effect of dielectric and magnetic materials and the heterogeneous interface form multiple polarizations, conductive losses and multiple loss mechanisms to optimize impedance matching and attenuation performance, which is conducive to excellent absorption performance. More importantly, the radar cross section (RCS) reduction is as high as 24.02 dB·m2, which has proven to have a good absorption effect in actual application environments. This work combines the advantages of Co@NCP and CNF very well, which provides guidance for designing EM waves nanocomposite fiber absorbers with lightweight and strong absorbing properties.

Enhanced microwave absorption properties of Ti3AlC2 particles modified by a facile preoxidation strategy

MAX phases are considered to be promising microwave absorbing materials in fifth-generation (5G) communications, but their high electrical conductivity causes impedance mismatching, weakening their ability to absorb microwaves. Here, we present a universal preoxidation strategy to improve the impedance matching and the microwave absorption performance of a Ti3AlC2 MAX phase absorbing material. The microwave absorption properties of Ti3AlC2 particles were enhanced after preoxidation at temperatures of 500-700 °C for only 30 min in air, as compared with unoxidized Ti3AlC2 particles. More interestingly, the 600 °C-preoxidized Ti3AlC2 material reached a minimum reflection loss (RLmin) value of -50.56 dB at 8.87 GHz, superior to -12.36 dB at 12.82 GHz for the original Ti3AlC2 material. The preoxidized Ti3AlC2 particles were covered by a thin oxidation layer comprising both amorphous TiO2 (a-TiO2) and rutile TiO2 (R-TiO2). The oxidation layer endows the preoxidized Ti3AlC2 particles with good impedance matching, and a large number of nano-interfaces of a-TiO2/R-TiO2 and micro-interfaces of a-TiO2/Ti3AlC2 also contribute to the dielectric loss mechanism, thus improving its microwave absorption ability. This work provides a practical strategy for the fundamental study and the optimal design of MAX microwave absorbing materials.

Polymetallic red mud direct materialization strategy towards zero waste emission: Electromagnetic wave absorption conversion and sodium solidification

Red mud is an industrial hazardous alkaline solid waste, whereas it is rich in polymetallic components showing a high comprehensive utilization value. Direct materialization of red mud towards zero waste emission is a more reasonable and environmentally friendly strategy. In this work, a novel materialization approach of red mud via converting the polymetallic constituents into functional ferrite material by phase reconstruction with MnO2 was proposed. The mineral phase reconstruction, microstructure evolution, reaction interface observation, electromagnetic property, and the materialization conversion mechanism were investigated. It was found that the complicated phases in red mud were transferred to simple forms including the magnetic ferrites (Ca/Na/Al/Ti-bearing Mn ferrite) and weakly magnetic silicates ((Na,Al,Ca)2SiO3) after phase reconstruction. The reconstructed red mud after sintering at 1200 ℃ for 120min in air atmosphere had satisfactory electromagnetic property. Magnetism study demonstrated the soft magnetic property with maximum saturation magnetization of 34.22emu/g and coercivity of only 7.0Oe. Compared with the original red mud, effective electromagnetic wave absorption with reflection loss (RL) values of the reconstructed red mud below -20 dB were satisfied across a wider frequency bandwidth of 5-18GHz, and the minimum RL value was lower as -32.4dB with a thinner veneer thickness of 15mm, highlighting its excellent electromagnetic wave absorption performance. Moreover, Na solidification behaviors indicated that Na was solidified in the sintered product, which can reduce the possible environmental hazards of red mud alkalinity. The novel materialization treatment with zero waste emission exhibits a favorable application prospect with a large red mud batching ratio about 50wt%.

One-Click to 3D: Helical Carbon Nanotube-Mediated MXene Hierarchical Aerogel with Layer Spacing Engineering for Broadband Electromagnetic Wave Absorption.

MXenes are 2D materials known for their unique electromagnetic wave absorption (EMWA) properties arising from their varied composition and structure. In this study, a one-step ice-assisted process is utilized to directly transform 2D MXene into 3D single-layer MXene aerogels (SMAs). Furthermore, the interlayer spacing of the SMAs is optimized by incorporating helical carbon nanotubes (HCNTs). Because of the van der Waals interaction between the MXene nanosheets and HCNTs, the assembled HCNT@MXene aerogels (HMAs) exhibited a regular porous structure and moderate conductivity, leading to significantly enhanced electromagnetic responses, as demonstrated by finite element simulation. The HMAs showed an exceptional EMWA, with a minimum reflection loss of -51.45 dB and an effective absorption bandwidth of 6.48 GHz at 3.0 wt.% filler ratio. Additionally, visualization of surface charge distribution and power loss density characteristics clarified the underlying EMWA mechanisms. By employing a hollow structure gradient metamaterial design, the effective EMWA bandwidth is further expanded to 13.98 GHz. Additionally, HMAs exhibited the maximum radar cross-section reduction values with 27.08 dBm2. Moreover, the HMAs exhibited excellent thermal insulation capability. This paper presents a straightforward yet effective method for fabricating MXene aerogels and offers valuable insights for the development and application of MXene-aerogel-based EMW absorbers.

Bandwidth expansion effects and electromagnetic wave loss mechanisms in Y2Co8Fe9 powders with multiple particle size distributions

Electromagnetic interference and radiation demand advanced absorbing materials to moderate pollution. In this work, the wide bandwidth and strong absorption electromagnetic wave absorbing material Y2Co8Fe9 powder was prepared by the plasma-assisted ball milling method, and the microstructure and electromagnetic wave absorption mechanism were systematically investigated. The particle size of Y2Co8Fe9 powder was optimized to enhance absorption properties, resulting in a minimum reflection loss of −41.4 dB after 2 h of ball milling, with an effective absorption bandwidth (EAB) of 7.6 GHz at a thickness of 1.6 mm. The concept of average loss is introduced based on the synergistic effect of dielectric and magnetic losses. It is demonstrated that an average loss within 0.45 leads to desirable EAB values. These results demonstrate the significance of determining the influence of particle size distributions and average losses on material absorption performance, providing an innovative perspective to preparing efficient wave-absorbing materials.

High-Density Dual Atoms Pairs Coupling for Efficient Electromagnetic Wave Absorbers.

Dual atoms (DAs), characterized by flexible structural tunability and high atomic utilization, hold significant promise for atom-level coordination engineering. However, the rational design with high-density heterogeneous DAs pairs to promote electromagnetic wave (EMW) absorption performance remains a challenge. In this study, high-density Ni─Cu pairs coupled DAs absorbers are precisely constructed on a nitrogen-rich carbon substrate, achieving an impressive metal loading amount of 4.74wt.%, enabling a huge enhancement of the effective absorption bandwidth (EAB) of EMW from 0 to 7.8GHz. Furthermore, the minimum reflection loss (RLmin) is -70.96dB at a matching thickness of 3.60mm, corresponding to an absorption of >99.99% of the incident energy. Both experimental results and theoretical calculations indicate that the synergistic effect of coupled Ni─Cu pairs DAs sites results in the transfer of electron-rich sites from the initial N sites to the Cu sites, which induces a strong asymmetric polarization loss by this redistribution of local charge and significantly improves the EMW absorption performance. This work not only provides a strategy for the preparation of high-density DA pairs but also demonstrates the role of coupled DA pairs in precisely tuning coordination symmetry at the atomic level.

Multi-scale heterogeneous composite elastomer absorbers synergistically enhanced by CoNi nanospheres and carbon nanotubes

The advancement of high-performance absorbers is essential for applications in electromagnetic wave absorption (EWA) and stealth technologies. To enhance EWA performances, it is imperative to employ advanced design strategies that incorporate heterogeneous interfaces and multi-scale structures. In this study, we developed a composite elastomer demonstrating exceptional EWA characteristics using a two-step process involving liquid-phase reduction followed by thermal curing. High aspect ratio carbon nanotubes were integrated onto the surface of CoNi nanospheres, creating a multi-scale architecture with heterogeneous interfaces that ranged from zero-dimensional to two-dimensional. This innovative structural design significantly improved the EWA capabilities of the composite elastomer. Notably, even with only 15 wt% filler content, the composite elastomer achieved a minimum reflection loss of −54.4 dB at a thickness of 4 mm, alongside an adjustable effective absorption bandwidth exceeding 60 % of the 2–18 GHz frequency range. Additionally, it exhibited favorable mechanical strength and stretchability, enhancing its practical applicability. This work provides valuable insights into optimizing dielectric and magnetic properties through advanced structural design and underscores the potential for developing effective elastomer absorbers to deal with electromagnetic pollution in complex environment.

Multifunctional Anisotropic Aerogels for Intelligent Electromagnetic Wave Absorption

AbstractThe rapidly developing modern society has higher requirements for intelligent electromagnetic wave absorbing (EMA) materials than ever before. Herein, lightweight, multifunctional metal‐free carbon‐based aerogels (RCPs) with a longitudinal honeycomb porous framework and a transverse neatly layered structure are obtained by heat‐treating graphene oxide/oxidized carbon nanotubes/hexachlorocyclotriphosphazene complex to simultaneously achieve the tunable EMA, flame retardancy, and thermal insulation. The anisotropic structure ensures the tunable properties of the carbon aerogels along with tilt angles according to environmental needs. The honeycomb porous structure effectively promotes multiple reflections and scatterings of electromagnetic waves compared with the layered structure, maximizing the penetration inside the material and thus a high EMA performance. The optimized R10C2P‐4 exhibits a minimum reflection loss in the longitudinal direction of−61.5 dB, while the value is as low as −22.4 dB in the transverse direction. Furthermore, the porous structure adequately inhibits the spread of heat, accompanied by the phosphorus species induced by hexachlorocyclotriphosphazene pyrolysis, endowing a good flame retardancy and thermal insulation with a low thermal conductivity of 20.6 mW m−1 K−1 in the longitudinal direction, rather than the transverse direction. This work provides an ingenious insight into the design of multifunctional EMA materials, adapting flexibly to various application requirements.

In-situ Construction of Petal-liked porous Co coating layers for electromagnetic wave absorption materials with rich interface-polarization

With the rapid advancements in 5G and communication technology, electromagnetic wave (EMW) absorption materials play a crucial role in reducing interference, enhancing the efficiency and stability of communication equipment, and minimizing maintenance requirements. However, the challenge remains in effectively utilizing cost-effective raw materials with simple synthesis conditions to achieve highly consistent product quality and superior EWM absorption performance. This study employs carbon nanofibers (CNFs) derived from polyacrylonitrile (PAN) as substrates and utilizes electrodeposition technology to create a composite material that exhibits both magnetic and dielectric properties. The results show that the petal-like porous Co composite CNFs (Co/CNFs) demonstrates excellent impedance matching and significant EMW absorption capabilities, which can be attributed to synergistic microstructural effects and multiple loss mechanisms. At a filling ratio of 20 wt% and a thickness of 1.8 mm, the Co/CNFs achieves a minimum reflection loss of −45 dB, extending the effective absorption bandwidth to 4.6 GHz. Performance assessment through power loss density (PLD) and radar cross-section (RCS) simulations evaluates the material’s capabilities, confirming the enhanced performance of Co/CNFs compared to the perfect electrical conductor (PEC). This efficient preparation method holds substantial potential for practical applications and serves as a comprehensive guide for achieving a balance between high performance, efficiency, and cost-advantages.

Core Double-Shell FeCo@SiO2@PPy Nanocomposites for Tunable and Broadband Electromagnetic Wave Absorption

Electromagnetic wave absorption materials are essential for dealing with military stealth and electromagnetic pollution. However, challenges remain in regards to material stability and achieving broadband absorption. Constructing magnetic-dielectric core-shell structural composites with good morphology is one of the effective strategies to realize high-performance electromagnetic wave absorption. Herein, FeCo@SiO2@polypyrrole (PPy) core double-shell nanocomposite with uniform shell thicknesses is synthesized by environmentally friendly polyol method, sol-gel method and in-situ oxidative polymerization method. FeCo@SiO2@PPy nanocomposites with different PPy shell thicknesses were synthesized, and tunable electromagnetic wave absorption had been achieved. The reasonable combination of magnetic and dielectric components and the design of core double-shell structure optimized impedance matching and attenuation characteristics, resulting in strong and broadband electromagnetic wave absorption (minimum reflection loss: -62.7 dB, effective absorption bandwidth: 7.0 GHz). This work could initiate a new insight into the design and modulation of advanced electromagnetic wave absorption materials with strong and broadband absorption properties.

Tunable magnetic properties and microwave absorbing properties of (Nd1-xYx)2Fe17N3-δ

Magnetic microwave absorbing materials of rare earth-transition metal (R-T) intermetallic compounds have the advantage of high absorbing performance, low matching thickness, and rich tunability. In this work, we report the magnetic and microwave absorbing properties of R-T intermetallic compounds (Nd1-xYx)2Fe17N3-δ (x = 0 ∼ 1). The crystalline structure of these compounds transitions from Th2Zn17-type rhombohedral (for x < 0.6) to Th2Ni17-type hexagonal (for x > 0.8) as the composition varies, attributed to the reduction in lattice volume. The saturation magnetization (Ms) of the (Nd1-xYx)2Fe17N3-δ remains almost unchanged as x changes. However, the out-of-plane anisotropy field decreases significantly from 111kOe to 25kOe while x increases. The high-frequency magnetic permeability of the material is also significantly elevated and thus leads to a significant enhancement in microwave absorbing performance. A 5.8 GHz maximum effective absorption bandwidth (EAB, RL < -10 dB) could be achieved within a thickness of only 1.1 mm for Y2Fe17N3-δ(x = 1)/paraffin composite primarily due to its heavy magnetic loss. Furthermore, the minimum reflection loss (RL) reaches −49 dB at 6.6 GHz with a thickness of 2.2 mm. The tunable magnetic properties and excellent microwave absorbing performances of (Nd1-xYx)2Fe17N3-δ make it a strong contender for applications in high-performance microwave absorbing materials.

NIR-driven self-healing PANI/Ag/ basalt scales coatings with robust anticorrosion and microwave absorption properties

Addressing electromagnetic interference and corrosion of electronic devices and communications facilities in the marine environments with high humidity and high salt spray remains a challenge. In this study, polyaniline/silver/basalt scales (PANI/Ag/BS) fillers were prepared to obtain dual functions of microwave absorption (MA) and corrosion resistance, whereas the introduce of PANI not only enabled the fillers to possess the photo-thermal effect, but also improved their compatibility with epoxy resin. The MA performance test proves that the PANI/Ag/BS has a minimum reflection loss (RL) of -30.55 dB at a thickness of 2.08 mm and achieves an effective absorption bandwidth (EAB) value of 5.28 GHz at a thickness of 2.40 mm. Meanwhile, the EIS measurement demonstrates that the coating has exceptional performance during the 240 h immersion, and the low-frequency impedance value (|Z|0.01Hz) is about 2.5 × 108 Ω·cm2. In addition, the photothermal effect of PANI/Ag/BS endows the coating with remarkable photothermal repair capability, which enabled self-healing within 30 s. This work opens another avenue for the development of bifunctional coating with enhanced anti-corrosion and microwave absorption.

Preparation and Electromagnetic-Wave-Absorption Properties of Cement-Based Materials with Graphite Tailings and Steel Fiber

The development of functional building materials that can absorb electromagnetic radiation is important for preventing and controlling electromagnetic pollution in urban areas. In this study, cement-based electromagnetic wave (EMW)-absorbing materials were created using graphite tailings (GTs) as a conductive admixture and steel fiber (SF) as an EMW absorber, which resulted in materials with a wide effective bandwidth and high reflection loss (RL). In particular, a GT–cement matrix with excellent mechanical and electrical properties was obtained. This study explored the influence mechanism of the SF content on the mechanical, electrical, and EMW-absorption properties of cement-based materials under the synergistic effect of GTs and SF. Findings demonstrate that the combination of GTs and SF notably improved the electrical and EMW-absorption characteristics of the cement-based materials. Optimal EMW-absorption properties were observed for a combination of 30% GTs and 6% SF. A developed cement-based EMW-absorbing material with a thickness of 20 mm displayed a minimum RL of −25.78 dB in the frequency range of 0.1–5 GHz, with an effective bandwidth of 0.953 GHz. Thus, the cement-based composite materials developed in this study have excellent EMW-absorption performance, which provides an effective strategy for preventing and controlling electromagnetic pollution in urban spaces.

Schottky Interface Engineering in Ti3C2Tx/ZnS Organic Hydrogels for High‐Performance Multifunctional Flexible Absorbers

AbstractWith the rapid advancement of wearable electronics, soft robotics, and camouflage technologies, there is an urgent demand for flexible, multifunctional electromagnetic wave absorbing materials. Traditional absorbers, including metal‐ and carbon‐based materials, often lack the flexibility required for such applications. In this work, a novel strategy is proposed for developing a flexible absorber by combining a conductive filler with a Schottky heterogeneous interface and a polymer network framework. Ti3C2Tx MXene is modified with ZnS via a low‐temperature hydrothermal method, forming a Ti3C2Tx/ZnS composite. This composite is subsequently embedded in a copolymer matrix of polyvinyl alcohol (PVA) and acrylamide (AAm), dispersed in a binary water‐glycerol solution. The Schottky interface between Ti3C2Tx and ZnS enhances electron transfer at the heterophase boundary, significantly improving interface polarisation. Simultaneously, interactions between water and glycerol restrict the rotation of polar molecules under external electromagnetic fields, optimising polarisation loss within the gel. Experimental results demonstrate that the Ti3C2Tx/ZnS gel achieves a minimum reflection loss (RLmin) of −43.76 dB at 8.79 GHz, with an effective absorption bandwidth (EAB) covering the entire X‐band. Additionally, the gel exhibit exceptional stretchability, frost resistance, shape adaptability, and photothermal conversion properties.

Facile synthesis of novel nitrogen-doped diamond with excellent microwave absorption and thermal conductive performance

Herein, nitrogen doped polycrystalline diamond was prepared using the microwave plasma chemical vapor deposition (MPCVD) method with H2–CH4–N2 gas sources to achieve excellent electromagnetic (EM) wave absorption and thermal management properties. The effect of the nitrogen content (0 to 50 ppm) on its performance was studied. The 25-ppm nitrogen doped diamond demonstrated excellent EM wave absorption performance, achieving a minimum reflection loss (RLmin) of −44.8 dB at 6.7 GHz and a maximum effective absorption band (EAB) of 5.4 GHz (3.7–9.1 GHz). The superior absorption performance could be attributed to synergistic attenuation mechanisms including dipole and interface polarization, conduction loss, eddy current loss, and magnetic polarization, intensified by nitrogen vacancy centers. This multifunctional material, combining high thermal conductivity with effective low-frequency EM wave absorption, showed promise for applications in 5G communications and electronic devices.