The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(S...The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(SiC_(nws))/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiC_(nws)skeleton,which collaborative configuration by 3D printing and freeze casting assembly.The con-structed porous structure optimizes the impedance matching degree and scattering intensity,the maximum effective absorption bandwidth(EAB_(max))of 5.9 GHz and the minimum reflection loss(RL_(min))of−41.4 dB can be realized.Considering the inherent oxidation resistance of SiC,the composites present well-maintained absorption performance at 600℃.Even at 1100℃,the EAB_(max)of 4.9 GHz and RLmin of−30.4 dB also demonstrate the high-temperature absorption stability of the composites,indicating exceptional wave absorption properties and thermal stability.The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant.This work clarifies the impact of structure and component synergy on wave absorption behavior,and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.展开更多
Ceramic matrix composites(CMC)are widely utilized in high-temperature components of aero-engines for load-bearing and electromagnetic stealth synergy due to their superior toughening and designable electromagnetic pro...Ceramic matrix composites(CMC)are widely utilized in high-temperature components of aero-engines for load-bearing and electromagnetic stealth synergy due to their superior toughening and designable electromagnetic properties.However,the design of ultra-broadband electromagnetic wave(EMW)absorp-tion at thin thicknesses(d<10 mm)has been difficult and focused,especially the design of metama-terial.Inspired by 3D printing technology and the structural characteristic of 2D CMC,this study inge-niously devised and proposed a novel carbon fiber gradient periodic structure in Al_(2)O_(3f)/SiOC composites to enhance the ultra-broadband EMW absorption properties at a wide temperature range.By optimizing the geometric structure parameters,the Al_(2)O_(3f)/SiOC composites with the carbon fiber gradient periodic structure have exhibited exceptional ultra-broadband EMW absorption properties at elevated tempera-tures and excellent mechanical performance.The composites have attained a minimum reflection loss(RLmin)of-30 dB and a high absorption efficiency of more than 84%,ranging from 9.3 to 40 GHz at a thickness of 9 mm.Due to the temperature insensitivity of discrete periodic structures,the composites can adapt to high temperatures up to 700℃.Additionally,compared to the Al_(2)O_(3f)/SiOC composites,the flexural strength and fracture toughness of the Al_(2)O_(3f)/SiOC composites with carbon fiber gradient peri-odic structure have significantly increased to 398 MPa and 15.6 MPa m1/2,respectively.This work breaks through the limitation of the design and fabrication of 3D periodic structures in CMC,creating a novel oxide-CMC with ultra-broadband EMW absorption properties at a wide temperature range and enhanced mechanical properties.展开更多
With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite h...With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite heterogeneous interface are constructed successfully to optimize the electromagnetic loss capacity.The macro–micro-synergistic graphene aerogel formed by the ice template‑assisted 3D printing strategy is cut by silicon carbide nanowires(SiC_(nws))grown in situ,while boron nitride(BN)interfacial structure is introduced on graphene nanoplates.The unique composite structure forces multiple scattering of incident EMWs,ensuring the combined effects of interfacial polarization,conduction networks,and magnetic-dielectric synergy.Therefore,the as-prepared composites present a minimum reflection loss value of−37.8 dB and a wide effective absorption bandwidth(EAB)of 9.2 GHz(from 8.8 to 18.0 GHz)at 2.5 mm.Besides,relying on the intrinsic high-temperature resistance of SiC_(nws) and BN,the EAB also remains above 5.0 GHz after annealing in air environment at 600℃ for 10 h.展开更多
Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,how...Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,however,constrain their delicate constructions.Herein,an innovative alternative is proposed:carrageenan-assistant cations-regulated(CACR)strategy,which induces a series of sulfides nanoparticles rooted in situ on the surface of carbon matrix.This unique configuration originates from strategic vacancy formation energy of sulfides and strong sulfides-carbon support interaction,benefiting the delicate construction of defects-rich heterostructures in M_(x)S_(y)/carbon composites(M-CAs).Impressively,these generated sulfur vacancies are firstly found to strengthen electron accumulation/consumption ability at heterointerfaces and,simultaneously,induct local asymmetry of electronic structure to evoke large dipole moment,ultimately leading to polarization coupling,i.e.,defect-type interfacial polarization.Such“Janus effect”(Janus effect means versatility,as in the Greek two-headed Janus)of interfacial sulfur vacancies is intuitively confirmed by both theoretical and experimental investigations for the first time.Consequently,the sulfur vacancies-rich heterostructured Co/Ni-CAs displays broad absorption bandwidth of 6.76 GHz at only 1.8 mm,compared to sulfur vacancies-free CAs without any dielectric response.Harnessing defects-rich heterostructures,this one-pot CACR strategy may steer the design and development of advanced nanomaterials,boosting functionality across diverse application domains beyond electromagnetic response.展开更多
Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significan...Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significant challenging in regulating local phase evolution.Herein,accordion-shaped Co/Co_(3)O_(4)@N-doped carbon nanosheets(Co/Co_(3)O_(4)@NC)with gradient magnetic heterointerfaces have been fabricated via the cooperative high-temperature carbonization and lowtemperature oxidation process.The results indicate that the surface epitaxial growth of crystal Co_(3)O_(4) domains on local Co nanoparticles realizes the adjustment of magnetic-heteroatomic components,which are beneficial for optimizing impedance matching and interfacial polarization.Moreover,gradient magnetic heterointerfaces simultaneously realize magnetic coupling,and long-range magnetic diffraction.Specifically,the synthesized Co/Co_(3)O_(4)@NC absorbents display the strong electromagnetic wave attenuation capability of−53.5 dB at a thickness of 3.0 mm with an effective absorption bandwidth of 5.36 GHz,both are superior to those of single magnetic domains embedded in carbon matrix.This design concept provides us an inspiration in optimizing interfacial polarization,regulating magnetic coupling and promoting electromagnetic wave absorption.展开更多
Currently,the demand for electromagnetic wave(EMW)absorbing materials with specific functions and capable of withstanding harsh environments is becoming increasingly urgent.Multi-component interface engineering is con...Currently,the demand for electromagnetic wave(EMW)absorbing materials with specific functions and capable of withstanding harsh environments is becoming increasingly urgent.Multi-component interface engineering is considered an effective means to achieve high-efficiency EMW absorption.However,interface modulation engineering has not been fully discussed and has great potential in the field of EMW absorption.In this study,multi-component tin compound fiber composites based on carbon fiber(CF)substrate were prepared by electrospinning,hydrothermal synthesis,and high-temperature thermal reduction.By utilizing the different properties of different substances,rich heterogeneous interfaces are constructed.This effectively promotes charge transfer and enhances interfacial polarization and conduction loss.The prepared SnS/SnS_(2)/SnO_(2)/CF composites with abundant heterogeneous interfaces have and exhibit excellent EMW absorption properties at a loading of 50 wt%in epoxy resin.The minimum reflection loss(RL)is−46.74 dB and the maximum effective absorption bandwidth is 5.28 GHz.Moreover,SnS/SnS_(2)/SnO_(2)/CF epoxy composite coatings exhibited long-term corrosion resistance on Q235 steel surfaces.Therefore,this study provides an effective strategy for the design of high-efficiency EMW absorbing materials in complex and harsh environments.展开更多
Non-stoichiometric carbides have been proven to be effective electromagnetic wave(EMW)absorbing materials.In this study,phase and morphology of XZnC(X=Fe/Co/Cu)loaded on a three dimensional(3D)network structure melami...Non-stoichiometric carbides have been proven to be effective electromagnetic wave(EMW)absorbing materials.In this study,phase and morphology of XZnC(X=Fe/Co/Cu)loaded on a three dimensional(3D)network structure melamine sponge(MS)carbon composites were investigated through vacuum filtration followed by calcination.The FeZnC/CoZnC/CuZnC with carbon nanotubes(CNTs)were uniformly dispersed on the surface of melamine sponge carbon skeleton and Co-containing sample exhibits the highest CNTs concentration.The minimum reflection loss(RL_(min))of the CoZnC/MS composite(m_(composite):m_(paraffin)=1:1,m represents mass)reached-33.60 dB,and the effective absorption bandwidth(EAB)reached 9.60 GHz.The outstanding electromagnetic wave absorption(EMWA)properties of the CoZnC/MS composite can be attributed to its unique hollow structure,which leads to multiple reflections and scattering.The formed conductive network improves dielectric and conductive loss.The incorporation of Co enhances the magnetic loss capability and optimizes interfacial polarization and dipole polarization.By simultaneously improving dielectric and magnetic losses,ex-cellent impedance matching performance is achieved.The clarification of element replacement in XZnC/MS composites provides an effi-cient design perspective for high-performance non-stoichiometric carbide EMW absorbers.展开更多
Reasonable manipulation of component and microstructure is considered as a potential route to realize high-performance microwave absorber.In this paper,micro-sized hexapod-like CuS/Cu_(9)S_(5) composites were synthesi...Reasonable manipulation of component and microstructure is considered as a potential route to realize high-performance microwave absorber.In this paper,micro-sized hexapod-like CuS/Cu_(9)S_(5) composites were synthesized via a facile approach involving the solvothermal method and subsequent sulfuration treatment.The resultant CuS/Cu_(9)S_(5) exhibited superb microwave absorbing capacity with a minimum reflection loss(RLmin)of-59.38 dB at 2.7 mm.The maximum effective absorption bandwidth(EABmax)was 7.44 GHz(10.56-18 GHz)when the thickness was reduced to 2.3 mm.The outstanding microwave absorbing ability of CuS/Cu_(9)S_(5) composites is mainly related to its unique hexapod shape and the formation of heterogeneous interfaces.The unique hexapod shape significantly promotes the multi-reflection of the incident electromagnetic wave(EMW)increasing the attenuation path of EMWs in the material.Hetero-geneous interfaces between CuS/Cu_(9)S_(5) enable powerful interface polarization,contributing to the atten-uation of EMWs propagating in the medium.In addition,the EMW absorption performance of CuS/Cu_(9)S_(5) composites is also inseparable from the conduction loss.This study provides a strong reference for the research of EMW absorbent materials based on transition metal sulfides.展开更多
To realize the application of electromagnetic wave absorption(EWA)devices in humid marine environments,bifunctional EWA materials with better EWA capacities and anticorrosion properties have great exploration signific...To realize the application of electromagnetic wave absorption(EWA)devices in humid marine environments,bifunctional EWA materials with better EWA capacities and anticorrosion properties have great exploration significance and systematic research re-quirements.By utilizing the low-cost and excellent magnetic and stable chemical characteristics of barium ferrite(BaFe_(12)O_(19))and using the high dielectric loss and excellent chemical inertia of nanocarbon clusters,a new type of nanocomposites with carbon nanoclusters en-capsulating BaFe_(12)O_(19)was designed and synthesized by combining an impregnation method and a high-temperature calcination strategy.Furthermore,Ce-Mn ions were introduced into the BaFe_(12)O_(19)lattice to improve the dielectric and magnetic properties of BaFe_(12)O_(19)cores significantly,and the energy band structure of the doped lattice and the orders of Ce replacing Fe sites were calculated.Benefiting from Ce-Mn ion doping and carbon nanocluster encapsulation,the composite material exhibited excellent dual functionality of corrosion resist-ance and EWA.When BaCe_(0.2)Mn_(0.3)Fe_(11.5)O_(19)-C(BCM-C)was calcined at 600°C,the minimum reflection loss of-20.1 dB was achieved at 14.43 GHz.The Ku band’s effective absorption bandwidth of 4.25 GHz was achieved at an absorber thickness of only 1.3 mm.The BCM-C/polydimethylsiloxane coating had excellent corrosion resistance in the simulated marine environment(3.5wt%NaCl solution).The|Z|0.01Hz value of BCM-C remained at 106Ω·cm^(2)after 12 soaking days.The successful preparation of the BaFe_(12)O_(19)composite en-capsulated with carbon nanoclusters provides new insights into the preparation of multifunctional absorbent materials and the fabrication of absorbent devices applied in humid marine environments in the future.展开更多
The morphological distribution of absorbent in composites is equally important with absorbents for the overall electromagnetic properties,but it is often ignored.Herein,a comprehensive consideration including electrom...The morphological distribution of absorbent in composites is equally important with absorbents for the overall electromagnetic properties,but it is often ignored.Herein,a comprehensive consideration including electromagnetic component regulation,layered arrangement structure,and gradient concentration distribution was used to optimize impedance matching and enhance electromagnetic loss.On the microscale,the incorporation of magnetic Ni nanoparticles into MXene nanosheets(Ni@MXene)endows suitable intrinsic permittivity and permeability.On the macroscale,the layered arrangement of Ni@MXene increases the effective interaction area with electromagnetic waves,inducing multiple reflection/scattering effects.On this basis,according to the analysis of absorption,reflection,and transmission(A-R-T)power coefficients of layered composites,the gradient concentration distribution was constructed to realize the impedance matching at low-concentration surface layer,electromagnetic loss at middle concentration interlayer and microwave reflection at high-concentration bottom layer.Consequently,the layered gradient composite(LG5-10-15)achieves complete absorption coverage of X-band at thickness of 2.00-2.20 mm with RL_(min) of-68.67 dB at 9.85 GHz in 2.05 mm,which is 199.0%,12.6%,and 50.6%higher than non-layered,layered and layered descending gradient composites,respectively.Therefore,this work confirms the importance of layered gradient structure in improving absorption performance and broadens the design of high-performance microwave absorption materials.展开更多
W-type barium-nickel ferrite(BaNi_(2)Fe_(16)O_(27))is a highly promising material for electromagnetic wave(EMW)absorption be-cause of its magnetic loss capability for EMW,low cost,large-scale production potential,high...W-type barium-nickel ferrite(BaNi_(2)Fe_(16)O_(27))is a highly promising material for electromagnetic wave(EMW)absorption be-cause of its magnetic loss capability for EMW,low cost,large-scale production potential,high-temperature resistance,and excellent chemical stability.However,the poor dielectric loss of magnetic ferrites hampers their utilization,hindering enhancement in their EMW-absorption performance.Developing efficient strategies that improve the EMW-absorption performance of ferrite is highly desired but re-mains challenging.Here,an efficient strategy substituting Ba^(2+)with rare earth La^(3+)in W-type ferrite was proposed for the preparation of novel La-substituted ferrites(Ba_(1-x)LaxNi_(2)Fe_(15.4)O_(27)).The influences of La^(3+)substitution on ferrites’EMW-absorption performance and the dissipative mechanism toward EMW were systematically explored and discussed.La^(3+)efficiently induced lattice defects,enhanced defect-induced polarization,and slightly reduced the ferrites’bandgap,enhancing the dielectric properties of the ferrites.La^(3+)also enhanced the ferromagnetic resonance loss and strengthened magnetic properties.These effects considerably improved the EMW-absorption perform-ance of Ba_(1-x)LaxNi_(2)Fe_(15.4)O_(27)compared with pure W-type ferrites.When x=0.2,the best EMW-absorption performance was achieved with a minimum reflection loss of-55.6 dB and effective absorption bandwidth(EAB)of 3.44 GHz.展开更多
Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band ...Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band structure of graphene,regulating its bandgap and electrical properties by introducing heteroatoms is considered a feasible solution.Herein,metal-nitrogen doping reduced graphene oxide(M–N-RGO)was prepared by embedding a series of single metal atoms M–N_(4) sites(M=Mn,Fe,Co,Ni,Cu,Zn,Nb,Cd,and Sn)in RGO using an N-coordination atom-assisted strategy.These composites had adjustable conductivity and polarization to optimize dielectric loss and impedance matching for efficient EMWA performance.The results showed that the minimum reflection loss(RL_(min))of Fe–N-RGO reaches−74.05 dB(2.0 mm)and the maximum effective absorption bandwidth(EAB_(max))is 7.05 GHz(1.89 mm)even with a low filler loading of only 1 wt%.Combined with X-ray absorption spectra(XAFS),atomic force microscopy,and density functional theory calculation analysis,the Fe–N_(4) can be used as the polarization center to increase dipole polarization,interface polarization and defect-induced polarization due to d-p orbital hybridization and structural distortion.Moreover,electron migration within the Fe further leads to conduction loss,thereby synergistically promoting energy attenuation.This study demonstrates the effectiveness of metal-nitrogen doping in regulating the graphene′s dielectric properties,which provides an important basis for further investigation of the loss mechanism.展开更多
Metal-organic frameworks(MOFs)have attracted significant interest as self-templates and precursors for the synthesis of carbon-based composites aimed at electromagnetic wave(EMW)absorption.However,the utilization of h...Metal-organic frameworks(MOFs)have attracted significant interest as self-templates and precursors for the synthesis of carbon-based composites aimed at electromagnetic wave(EMW)absorption.However,the utilization of high-temperature treatments has introduced uncertainties regarding the compositions and microstructures of resulting derivatives.Additionally,complete carbonization has led to diminished yields of the produced carbon composites,significantly limiting their practical applications.Consequently,the exploration of pristine MOF-based EMW absorbers presents an intriguing yet challenging endeavor,primarily due to inherently low electrical conductivity.In this study,we showcase the utilization of structurally robust Zr-MOFs as scaffolds to build highly conductive Zr-MOF/PPy composites via an inner-outer dual-modification approach,which involves the production of conducting polypyrrole(PPy)both within the confined nanoporous channels and the external surface of Zr-MOFs via post-synthetic modification.The interconnection of confined PPy and surface-lined PPy together leads to a consecutive and extensive conducting network to the maximum extent.This therefore entails outstanding conductivity up to~14.3 S cm^(-1) in Zr-MOF/PPy composites,which is approximately 1-2 orders of magnitude higher than that for conductive MOF nanocomposites constructed from either inner or outer modification.Benefiting from the strong and tunable conduction loss,as well as the induced dielectric polarization originated from the porous structures and MOF-polymer interfaces,Zr-MOF/PPy exhibits excellent microwave attenuation capabilities and a tunable absorption frequency range.Specifically,with only 15 wt.%loading,the minimum reflection loss(RLmin)can reach up to-67.4 dB,accompanied by an effective absorption bandwidth(EAB)extending to 6.74 GHz.Furthermore,the microwave absorption characteristics can be tailored from the C-band to the Ku-band by adjusting the loading of PPy.This work provides valuable insights into the fabrication of conductive MOF composites by presenting a straightforward pathway to enhance and reg-ulate electrical conduction in MOF-based nanocomposites,thus paving a way to facilely fabricate pristine MOF-based microwave absorbers.展开更多
The preparation of electromagnetic(EM)wave absorption materials provided with the characteristics of thin matching thickness,broad bandwidth,and mighty absorption intensity is an efficient solution to current EM pollu...The preparation of electromagnetic(EM)wave absorption materials provided with the characteristics of thin matching thickness,broad bandwidth,and mighty absorption intensity is an efficient solution to current EM pollution.Herein,Graphene nanosheets(GN)were firstly fabricated via a facile high-energy ball milling method,subsequently high-purity 1T-MoS_(2) petals were uniformly anchored on the surface of GN to prepare 1T-MoS_(2)@GN nanocomposites.Plentiful multiple reflection and scattering of EM waves in a distinctive multidimensional structure formed by GN and 1T-MoS_(2),copious polarization loss consisting of interfacial polarization loss and dipolar polarization loss severally derived from multitudinous heterointerfaces and profuse electric dipoles in 1T-MoS_(2)@GN,and mighty conduction loss originated from plentiful induced current in 1T-MoS_(2)@GN generated via the migration of massive electrons,all of which endowed 1T-MoS_(2)@GN nanocomposites with exceptional EM wave absorption performances.The minimum reflection loss(RLmin)of 1T-MoS_(2)@GN reached–50.14 dB at a thickness of only 2.10 mm,and the effective absorption bandwidth(EAB)was up to 6.72 GHz at an ultra-thin matching thickness of 1.84 mm.Moreover,the radar scattering cross section(RCS)reduction value of 36.18 dB m2 at 0°could be achieved as well,which ulteriorly validated the tremendous potential of 1T-MoS_(2)@GN nanocomposites in practical applications.展开更多
As a novel 2D material,Ti_(3)C_(2)T_(x)-MXene has become a major area of interest in the field of microwave absorption(MA).However,the MA effect of common Ti_(3)C_(2)T_(x)-MXene is not prominent and often requires com...As a novel 2D material,Ti_(3)C_(2)T_(x)-MXene has become a major area of interest in the field of microwave absorption(MA).However,the MA effect of common Ti_(3)C_(2)T_(x)-MXene is not prominent and often requires complex processes or combinations of other ma-terials to achieve enhanced performance.In this context,a kind of gradient woodpile structure using common Ti_(3)C_(2)T_(x)-MXene as MA ma-terial was designed and manufactured through direct ink writing(DIW)3D printing.The minimum reflection loss(RL_(min))of the Ti_(3)C_(2)T_(x)-MXene-based gradient woodpile structures with a thickness of less than 3 mm can reach-70 dB,showing considerable improve-ment compared with that of a completely filled structure.In addition,the effective absorption bandwidth(EAB)reaches 7.73 GHz.This study demonstrates that a Ti_(3)C_(2)T_(x)-MXene material with excellent MA performance and tunable frequency band can be successfully fab-ricated with a macroscopic structural design and through DIW 3D printing without complex material hybridization and modification,of-fering broad application prospects by reducing electromagnetic wave radiation and interference.展开更多
The rising concern over electromagnetic (EM) pollution is re-sponsible for the rapid progress in EM interference (EMI) shielding and EM wave absorption in the last few years, and carbon materials with a large sur-face...The rising concern over electromagnetic (EM) pollution is re-sponsible for the rapid progress in EM interference (EMI) shielding and EM wave absorption in the last few years, and carbon materials with a large sur-face area and high porosity have been investigated. Compared to other car-bon materials, biomass-derived carbon (BC) are considered efficient and eco-friendly materials for this purpose. We summarize the recent advances in BC materials for both EMI shielding and EM wave absorption. After a brief overview of the synthesis strategies of BC materials and a precise out-line of EM wave interference, strategies for improving their EMI shielding and EM wave absorption are discussed. Finally, the existing challenges and the future prospects for such materials are briefly summarized.展开更多
The intrinsic high magnetocrystalline anisotropy equivalent field can help the hexaferrites break through Snoek’s limit and increase the resonance frequency.This is advantageous for microwave absorption applications ...The intrinsic high magnetocrystalline anisotropy equivalent field can help the hexaferrites break through Snoek’s limit and increase the resonance frequency.This is advantageous for microwave absorption applications in the mid to low-frequency range of gigahertz.In this study,we prepared Z-type Ba_(3)Co_(1.6−x)Zn_(x)Cu_(0.4)Fe_(24)O_(41)hexaferrites using the sol-gel auto-combustion method.By changing the ratio of Co and Zn ions,the magnetocrystalline anisotropy of ferrite is further ma-nipulated,resulting in significant changes in their magnetic resonance frequency and intensity.Ba_(3)Zn_(1.6)Cu_(0.4)Fe_(24)O_(41)with high-frequency resonance achieved the lowest reflectivity of−72.18 dB at 15.56 GHz,while Ba_(3)Co_(1.5)Zn_(0.1)Cu_(0.4)Fe_(24)O_(41)with stronger loss obtained the widest bandwidth of 4.93 GHz(6.14-11.07).Additionally,we investigated surface wave suppression properties previously overlooked.Ba_(3)Co_(1.5)Zn_(0.1)Cu_(0.4)Fe_(24)O_(41)can achieve a larger attenuation at low frequency under low thickness,which has an excellent effect on reducing backscattering.This work provides a useful reference for the preparation and application of high-performance magnetic-loss materials.展开更多
Interface modulation is an important pathway for highly efficient electromagnetic wave absorption.Herein,tailored interfaces between Fe_(3)O_(4)particles and the hexagonal-YFeO_(3)(h-YFeO_(3))framework were constructe...Interface modulation is an important pathway for highly efficient electromagnetic wave absorption.Herein,tailored interfaces between Fe_(3)O_(4)particles and the hexagonal-YFeO_(3)(h-YFeO_(3))framework were constructed via facile self-assembly.The resulting interfa-cial electron rearrangement at the heterojunction led to enhanced dielectric and magnetic loss synergy.Experimental results and density function theory(DFT)simulations demonstrate a transition in electrical properties from a half-metallic monophase to metallic Fe_(3)O_(4)/h-YFeO_(3)composites,emphasizing the advantages of the formed heterointerface.The transformation of electron behavior is also accompan-ied by a redistribution of electrons at the Fe_(3)O_(4)/h-YFeO_(3)heterojunction,leading to the accumulation of localized electrons around the Y-O-Fe band bridge,consequently enhancing the polarization.A minimum reflection loss of-34.0 dB can be achieved at 12.0 GHz and 2.0 mm thickness with an effective bandwidth of 3.3 GHz due to the abundant interfaces,enhanced polarization,and rational impedance.Thus,the synergistic effects endow the Fe_(3)O_(4)/h-YFeO_(3)composites with high performance and tunable functional properties for efficient electromagnetic absorption.展开更多
The development of high-performance functional composites has become a research hotspot in response to the hazards of over-heating and electromagnetic radiation in modern electronic devices.Herein,we grew magnetic Fe_...The development of high-performance functional composites has become a research hotspot in response to the hazards of over-heating and electromagnetic radiation in modern electronic devices.Herein,we grew magnetic Fe_(3)O_(4)particles in situ on the MXene layer to obtain an MXene@Fe_(3)O_(4)composite with rich heterogeneous interfaces.Owing to the unique heterostructure and the synergistic effects of multiple electromagnetic wave absorption mechanisms,the composite achieved a minimum reflection loss of-27.14 dB and an effect-ive absorption bandwidth of 2.05 GHz at an absorption thickness of 2 mm.Moreover,the MXene@Fe_(3)O_(4)composite could be encapsu-lated in thermoplastic polyurethane(TPU)via thermal curing.The obtained composite elastomer exhibited a strong tensile strength,and its thermal diffusivity was 113%higher than that of pure TPU.Such additional mechanical properties and thermal conduction features render this composite elastomer an advanced electromagnetic absorber to adapt to the ever-changing environment for expanding practical applications.展开更多
Carbon-based sponge materials have attracted massive attention as electromagnetic wave(EMW)absorber candidates due to their lightweight and excellent electromagnetic(EM)attenuation capability.However,the high cost,com...Carbon-based sponge materials have attracted massive attention as electromagnetic wave(EMW)absorber candidates due to their lightweight and excellent electromagnetic(EM)attenuation capability.However,the high cost,complex fabrication process and limited EMW absorption bandwidth restrict their application.Herein,a hierarchical threedimensional(3D)cotton derived carbon fibers coated with core–shell structure Fe Ni nanoparticle@porous carbon(CCF/Fe Ni@PC)from MOF precursor were successfully constructed by coprecipitation and one-step pyrolysis methods.By regulating carbonization temperature,optimizing the electromagnetic parameters,outstanding electromagnetic absorption(EMA)performance was achieved.The CCF@Fe Ni/PC synthesized at 900℃demonstrates a-64.5 d B minimum reflection loss(RL_(min))at 15.39 GHz,and the effective absorption bandwidth(EAB)is 5.08 GHz when the thickness is only1.9 mm.Notably,the maximum EAB(EAB_(max))was extended8.18 GHz at 2.96 mm for Fe Ni-800.The excellent microwave absorption performance is attributed to the synergistic effect of enhanced dielectric loss and magnetic loss,good impedance matching as well as hierarchical multiple scattering and reflection of EMWs.The obtained CCF@Fe Ni/PC composites provide a novel and promising strategy for constructing lightweight low-cost efficient microwave absorption materials.展开更多
基金supported by the National Key R&D Program of China(No.2022YFB3707700)National Natural Science Foundation of China(No.52302121)+3 种基金Shanghai Sailing Program(No.23YF1454700)Shanghai Natural Science Foundation(No.23ZR1472700)Shanghai Post-doctoral Excellent Program(No.2022664)Shanghai Science and Technology Innovation Action Plan(No.21511104800).
文摘The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(SiC_(nws))/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiC_(nws)skeleton,which collaborative configuration by 3D printing and freeze casting assembly.The con-structed porous structure optimizes the impedance matching degree and scattering intensity,the maximum effective absorption bandwidth(EAB_(max))of 5.9 GHz and the minimum reflection loss(RL_(min))of−41.4 dB can be realized.Considering the inherent oxidation resistance of SiC,the composites present well-maintained absorption performance at 600℃.Even at 1100℃,the EAB_(max)of 4.9 GHz and RLmin of−30.4 dB also demonstrate the high-temperature absorption stability of the composites,indicating exceptional wave absorption properties and thermal stability.The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant.This work clarifies the impact of structure and component synergy on wave absorption behavior,and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.
基金supported by the National Key R&D Program of China(No.2022YFC2204500)the Aviation Science Foundation Project(No.2023Z055053001).
文摘Ceramic matrix composites(CMC)are widely utilized in high-temperature components of aero-engines for load-bearing and electromagnetic stealth synergy due to their superior toughening and designable electromagnetic properties.However,the design of ultra-broadband electromagnetic wave(EMW)absorp-tion at thin thicknesses(d<10 mm)has been difficult and focused,especially the design of metama-terial.Inspired by 3D printing technology and the structural characteristic of 2D CMC,this study inge-niously devised and proposed a novel carbon fiber gradient periodic structure in Al_(2)O_(3f)/SiOC composites to enhance the ultra-broadband EMW absorption properties at a wide temperature range.By optimizing the geometric structure parameters,the Al_(2)O_(3f)/SiOC composites with the carbon fiber gradient periodic structure have exhibited exceptional ultra-broadband EMW absorption properties at elevated tempera-tures and excellent mechanical performance.The composites have attained a minimum reflection loss(RLmin)of-30 dB and a high absorption efficiency of more than 84%,ranging from 9.3 to 40 GHz at a thickness of 9 mm.Due to the temperature insensitivity of discrete periodic structures,the composites can adapt to high temperatures up to 700℃.Additionally,compared to the Al_(2)O_(3f)/SiOC composites,the flexural strength and fracture toughness of the Al_(2)O_(3f)/SiOC composites with carbon fiber gradient peri-odic structure have significantly increased to 398 MPa and 15.6 MPa m1/2,respectively.This work breaks through the limitation of the design and fabrication of 3D periodic structures in CMC,creating a novel oxide-CMC with ultra-broadband EMW absorption properties at a wide temperature range and enhanced mechanical properties.
基金sponsored by National Natural Science Foundation of China(No.52302121,No.52203386)Shanghai Sailing Program(No.23YF1454700)+1 种基金Shanghai Natural Science Foundation(No.23ZR1472700)Shanghai Post-doctoral Excellent Program(No.2022664).
文摘With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite heterogeneous interface are constructed successfully to optimize the electromagnetic loss capacity.The macro–micro-synergistic graphene aerogel formed by the ice template‑assisted 3D printing strategy is cut by silicon carbide nanowires(SiC_(nws))grown in situ,while boron nitride(BN)interfacial structure is introduced on graphene nanoplates.The unique composite structure forces multiple scattering of incident EMWs,ensuring the combined effects of interfacial polarization,conduction networks,and magnetic-dielectric synergy.Therefore,the as-prepared composites present a minimum reflection loss value of−37.8 dB and a wide effective absorption bandwidth(EAB)of 9.2 GHz(from 8.8 to 18.0 GHz)at 2.5 mm.Besides,relying on the intrinsic high-temperature resistance of SiC_(nws) and BN,the EAB also remains above 5.0 GHz after annealing in air environment at 600℃ for 10 h.
基金financially supported by the National Natural Science Foundation of China(Grants nos.62201411,62371378,22205168,52302150 and 62304171)the China Postdoctoral Science Foundation(2022M722500)+1 种基金the Fundamental Research Funds for the Central Universities(Grants nos.ZYTS2308 and 20103237929)Startup Foundation of Xidian University(10251220001).
文摘Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,however,constrain their delicate constructions.Herein,an innovative alternative is proposed:carrageenan-assistant cations-regulated(CACR)strategy,which induces a series of sulfides nanoparticles rooted in situ on the surface of carbon matrix.This unique configuration originates from strategic vacancy formation energy of sulfides and strong sulfides-carbon support interaction,benefiting the delicate construction of defects-rich heterostructures in M_(x)S_(y)/carbon composites(M-CAs).Impressively,these generated sulfur vacancies are firstly found to strengthen electron accumulation/consumption ability at heterointerfaces and,simultaneously,induct local asymmetry of electronic structure to evoke large dipole moment,ultimately leading to polarization coupling,i.e.,defect-type interfacial polarization.Such“Janus effect”(Janus effect means versatility,as in the Greek two-headed Janus)of interfacial sulfur vacancies is intuitively confirmed by both theoretical and experimental investigations for the first time.Consequently,the sulfur vacancies-rich heterostructured Co/Ni-CAs displays broad absorption bandwidth of 6.76 GHz at only 1.8 mm,compared to sulfur vacancies-free CAs without any dielectric response.Harnessing defects-rich heterostructures,this one-pot CACR strategy may steer the design and development of advanced nanomaterials,boosting functionality across diverse application domains beyond electromagnetic response.
基金financially supported by the National Natural Science Foundation of China(52373271)Science,Technology and Innovation Commission of Shenzhen Municipality under Grant(KCXFZ20201221173004012)+1 种基金National Key Research and Development Program of Shaanxi Province(No.2023-YBNY-271)Open Testing Foundation of the Analytical&Testing Center of Northwestern Polytechnical University(2023T019).
文摘Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significant challenging in regulating local phase evolution.Herein,accordion-shaped Co/Co_(3)O_(4)@N-doped carbon nanosheets(Co/Co_(3)O_(4)@NC)with gradient magnetic heterointerfaces have been fabricated via the cooperative high-temperature carbonization and lowtemperature oxidation process.The results indicate that the surface epitaxial growth of crystal Co_(3)O_(4) domains on local Co nanoparticles realizes the adjustment of magnetic-heteroatomic components,which are beneficial for optimizing impedance matching and interfacial polarization.Moreover,gradient magnetic heterointerfaces simultaneously realize magnetic coupling,and long-range magnetic diffraction.Specifically,the synthesized Co/Co_(3)O_(4)@NC absorbents display the strong electromagnetic wave attenuation capability of−53.5 dB at a thickness of 3.0 mm with an effective absorption bandwidth of 5.36 GHz,both are superior to those of single magnetic domains embedded in carbon matrix.This design concept provides us an inspiration in optimizing interfacial polarization,regulating magnetic coupling and promoting electromagnetic wave absorption.
基金financially supported by the National Natural Science Foundation of China(No.52377026 and No.52301192)Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)+4 种基金Postdoctoral Fellowship Program of CPSF under Grant Number(No.GZB20240327)Shandong Postdoctoral Science Foundation(No.SDCXZG-202400275)Qingdao Postdoctoral Application Research Project(No.QDBSH20240102023)China Postdoctoral Science Foundation(No.2024M751563)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites).
文摘Currently,the demand for electromagnetic wave(EMW)absorbing materials with specific functions and capable of withstanding harsh environments is becoming increasingly urgent.Multi-component interface engineering is considered an effective means to achieve high-efficiency EMW absorption.However,interface modulation engineering has not been fully discussed and has great potential in the field of EMW absorption.In this study,multi-component tin compound fiber composites based on carbon fiber(CF)substrate were prepared by electrospinning,hydrothermal synthesis,and high-temperature thermal reduction.By utilizing the different properties of different substances,rich heterogeneous interfaces are constructed.This effectively promotes charge transfer and enhances interfacial polarization and conduction loss.The prepared SnS/SnS_(2)/SnO_(2)/CF composites with abundant heterogeneous interfaces have and exhibit excellent EMW absorption properties at a loading of 50 wt%in epoxy resin.The minimum reflection loss(RL)is−46.74 dB and the maximum effective absorption bandwidth is 5.28 GHz.Moreover,SnS/SnS_(2)/SnO_(2)/CF epoxy composite coatings exhibited long-term corrosion resistance on Q235 steel surfaces.Therefore,this study provides an effective strategy for the design of high-efficiency EMW absorbing materials in complex and harsh environments.
基金supported by the National Natural Science Foundation of China(Nos.52101274,52377026 and 52472131)Taishan Scholars and Young Experts Program of Shandong Province,China(No.tsqn202103057)+4 种基金Natural Science Foundation of Shandong Province,China(Nos.ZR2020QE011 and ZR2022ME089)the Qingchuang Talents Induction Program of Shandong Higher Education Institution,China(Research and Innovation Team of Structural-Functional Polymer Composites)Youth Top Talent Foundation of Yantai University,China(No.2219008)Graduate Innovation Foundation of Yantai University,China(No.GIFYTU2240)College Student Innovation and Entrepreneurship Training Program Project,China(No.202311066088).
文摘Non-stoichiometric carbides have been proven to be effective electromagnetic wave(EMW)absorbing materials.In this study,phase and morphology of XZnC(X=Fe/Co/Cu)loaded on a three dimensional(3D)network structure melamine sponge(MS)carbon composites were investigated through vacuum filtration followed by calcination.The FeZnC/CoZnC/CuZnC with carbon nanotubes(CNTs)were uniformly dispersed on the surface of melamine sponge carbon skeleton and Co-containing sample exhibits the highest CNTs concentration.The minimum reflection loss(RL_(min))of the CoZnC/MS composite(m_(composite):m_(paraffin)=1:1,m represents mass)reached-33.60 dB,and the effective absorption bandwidth(EAB)reached 9.60 GHz.The outstanding electromagnetic wave absorption(EMWA)properties of the CoZnC/MS composite can be attributed to its unique hollow structure,which leads to multiple reflections and scattering.The formed conductive network improves dielectric and conductive loss.The incorporation of Co enhances the magnetic loss capability and optimizes interfacial polarization and dipole polarization.By simultaneously improving dielectric and magnetic losses,ex-cellent impedance matching performance is achieved.The clarification of element replacement in XZnC/MS composites provides an effi-cient design perspective for high-performance non-stoichiometric carbide EMW absorbers.
基金supported by the National Natural Science Foundation of China(Nos.52377026 and 52301192)the Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)+3 种基金the Postdoctoral Fellow-ship Program of CPSF under Grant Number(No.GZB20240327)the Shandong Postdoctoral Science Foundation(No.SDCX-ZG-202400275)the Qingdao Postdoctoral Application Research Project(No.QDBSH20240102023)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites).
文摘Reasonable manipulation of component and microstructure is considered as a potential route to realize high-performance microwave absorber.In this paper,micro-sized hexapod-like CuS/Cu_(9)S_(5) composites were synthesized via a facile approach involving the solvothermal method and subsequent sulfuration treatment.The resultant CuS/Cu_(9)S_(5) exhibited superb microwave absorbing capacity with a minimum reflection loss(RLmin)of-59.38 dB at 2.7 mm.The maximum effective absorption bandwidth(EABmax)was 7.44 GHz(10.56-18 GHz)when the thickness was reduced to 2.3 mm.The outstanding microwave absorbing ability of CuS/Cu_(9)S_(5) composites is mainly related to its unique hexapod shape and the formation of heterogeneous interfaces.The unique hexapod shape significantly promotes the multi-reflection of the incident electromagnetic wave(EMW)increasing the attenuation path of EMWs in the material.Hetero-geneous interfaces between CuS/Cu_(9)S_(5) enable powerful interface polarization,contributing to the atten-uation of EMWs propagating in the medium.In addition,the EMW absorption performance of CuS/Cu_(9)S_(5) composites is also inseparable from the conduction loss.This study provides a strong reference for the research of EMW absorbent materials based on transition metal sulfides.
基金supported by the National Key R&D Program of China(Nos.2022YFB3504804 and 2023YFF0718303)the National Natural Science Foundation of China(Nos.51871219,52071324,52031014,and 52401255)+1 种基金Science and Technology Project of Shenyang City(No.22-101-0-27)Liaoning Institute of Science and Technology Doctoral Initiation Fund Project(No.2307B19).
文摘To realize the application of electromagnetic wave absorption(EWA)devices in humid marine environments,bifunctional EWA materials with better EWA capacities and anticorrosion properties have great exploration significance and systematic research re-quirements.By utilizing the low-cost and excellent magnetic and stable chemical characteristics of barium ferrite(BaFe_(12)O_(19))and using the high dielectric loss and excellent chemical inertia of nanocarbon clusters,a new type of nanocomposites with carbon nanoclusters en-capsulating BaFe_(12)O_(19)was designed and synthesized by combining an impregnation method and a high-temperature calcination strategy.Furthermore,Ce-Mn ions were introduced into the BaFe_(12)O_(19)lattice to improve the dielectric and magnetic properties of BaFe_(12)O_(19)cores significantly,and the energy band structure of the doped lattice and the orders of Ce replacing Fe sites were calculated.Benefiting from Ce-Mn ion doping and carbon nanocluster encapsulation,the composite material exhibited excellent dual functionality of corrosion resist-ance and EWA.When BaCe_(0.2)Mn_(0.3)Fe_(11.5)O_(19)-C(BCM-C)was calcined at 600°C,the minimum reflection loss of-20.1 dB was achieved at 14.43 GHz.The Ku band’s effective absorption bandwidth of 4.25 GHz was achieved at an absorber thickness of only 1.3 mm.The BCM-C/polydimethylsiloxane coating had excellent corrosion resistance in the simulated marine environment(3.5wt%NaCl solution).The|Z|0.01Hz value of BCM-C remained at 106Ω·cm^(2)after 12 soaking days.The successful preparation of the BaFe_(12)O_(19)composite en-capsulated with carbon nanoclusters provides new insights into the preparation of multifunctional absorbent materials and the fabrication of absorbent devices applied in humid marine environments in the future.
基金support for this work by Key Research and Development Project of Henan Province(Grant.No.241111232300)the National Natural Science Foundation of China(Grant.No.52273085 and 52303113)the Open Fund of Yaoshan Laboratory(Grant.No.2024003).
文摘The morphological distribution of absorbent in composites is equally important with absorbents for the overall electromagnetic properties,but it is often ignored.Herein,a comprehensive consideration including electromagnetic component regulation,layered arrangement structure,and gradient concentration distribution was used to optimize impedance matching and enhance electromagnetic loss.On the microscale,the incorporation of magnetic Ni nanoparticles into MXene nanosheets(Ni@MXene)endows suitable intrinsic permittivity and permeability.On the macroscale,the layered arrangement of Ni@MXene increases the effective interaction area with electromagnetic waves,inducing multiple reflection/scattering effects.On this basis,according to the analysis of absorption,reflection,and transmission(A-R-T)power coefficients of layered composites,the gradient concentration distribution was constructed to realize the impedance matching at low-concentration surface layer,electromagnetic loss at middle concentration interlayer and microwave reflection at high-concentration bottom layer.Consequently,the layered gradient composite(LG5-10-15)achieves complete absorption coverage of X-band at thickness of 2.00-2.20 mm with RL_(min) of-68.67 dB at 9.85 GHz in 2.05 mm,which is 199.0%,12.6%,and 50.6%higher than non-layered,layered and layered descending gradient composites,respectively.Therefore,this work confirms the importance of layered gradient structure in improving absorption performance and broadens the design of high-performance microwave absorption materials.
基金financially supported by the National Key R&D Program of China(No.2021YFB3502500)the Natur-al Science Foundation of Shandong Province,China(No.2022HYYQ-014)+5 种基金the“20 Clauses about Colleges and Uni-versities(new)”(Independent Training of Innovation Team)Program of Jinan,China(No.2021GXRC036)the Provin-cial Key Research and Development Program of Shandong,China(No.2021ZLGX01)the National Natural Science Foundation of China(No.22375115)the Joint Laboratory project of Electromagnetic Structure Technology(No.637-2022-70-F-037)the Discipline Construction Expenditure for Distinguished Young Scholars of Shandong University,China(No.31370089963141)the Qilu Young Scholar Program of Shandong University,China(No.31370082163127).
文摘W-type barium-nickel ferrite(BaNi_(2)Fe_(16)O_(27))is a highly promising material for electromagnetic wave(EMW)absorption be-cause of its magnetic loss capability for EMW,low cost,large-scale production potential,high-temperature resistance,and excellent chemical stability.However,the poor dielectric loss of magnetic ferrites hampers their utilization,hindering enhancement in their EMW-absorption performance.Developing efficient strategies that improve the EMW-absorption performance of ferrite is highly desired but re-mains challenging.Here,an efficient strategy substituting Ba^(2+)with rare earth La^(3+)in W-type ferrite was proposed for the preparation of novel La-substituted ferrites(Ba_(1-x)LaxNi_(2)Fe_(15.4)O_(27)).The influences of La^(3+)substitution on ferrites’EMW-absorption performance and the dissipative mechanism toward EMW were systematically explored and discussed.La^(3+)efficiently induced lattice defects,enhanced defect-induced polarization,and slightly reduced the ferrites’bandgap,enhancing the dielectric properties of the ferrites.La^(3+)also enhanced the ferromagnetic resonance loss and strengthened magnetic properties.These effects considerably improved the EMW-absorption perform-ance of Ba_(1-x)LaxNi_(2)Fe_(15.4)O_(27)compared with pure W-type ferrites.When x=0.2,the best EMW-absorption performance was achieved with a minimum reflection loss of-55.6 dB and effective absorption bandwidth(EAB)of 3.44 GHz.
基金supported by National Natural Science Foundation of China(NSFC 52432002,52372041,52302087)Heilongjiang Touyan Team Program,the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2021003)the Shanghai Aerospace Science and Technology Innovation Fund(SAST2022-60).
文摘Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band structure of graphene,regulating its bandgap and electrical properties by introducing heteroatoms is considered a feasible solution.Herein,metal-nitrogen doping reduced graphene oxide(M–N-RGO)was prepared by embedding a series of single metal atoms M–N_(4) sites(M=Mn,Fe,Co,Ni,Cu,Zn,Nb,Cd,and Sn)in RGO using an N-coordination atom-assisted strategy.These composites had adjustable conductivity and polarization to optimize dielectric loss and impedance matching for efficient EMWA performance.The results showed that the minimum reflection loss(RL_(min))of Fe–N-RGO reaches−74.05 dB(2.0 mm)and the maximum effective absorption bandwidth(EAB_(max))is 7.05 GHz(1.89 mm)even with a low filler loading of only 1 wt%.Combined with X-ray absorption spectra(XAFS),atomic force microscopy,and density functional theory calculation analysis,the Fe–N_(4) can be used as the polarization center to increase dipole polarization,interface polarization and defect-induced polarization due to d-p orbital hybridization and structural distortion.Moreover,electron migration within the Fe further leads to conduction loss,thereby synergistically promoting energy attenuation.This study demonstrates the effectiveness of metal-nitrogen doping in regulating the graphene′s dielectric properties,which provides an important basis for further investigation of the loss mechanism.
基金supported by the Fundamental Research Funds for the Central Universities(Nos.2232023D-01 and 2232023D-07)the Shanghai Science&Technology Committee(No.22ZR1403300)the National Natural Science Foundation of China(No.52372040).
文摘Metal-organic frameworks(MOFs)have attracted significant interest as self-templates and precursors for the synthesis of carbon-based composites aimed at electromagnetic wave(EMW)absorption.However,the utilization of high-temperature treatments has introduced uncertainties regarding the compositions and microstructures of resulting derivatives.Additionally,complete carbonization has led to diminished yields of the produced carbon composites,significantly limiting their practical applications.Consequently,the exploration of pristine MOF-based EMW absorbers presents an intriguing yet challenging endeavor,primarily due to inherently low electrical conductivity.In this study,we showcase the utilization of structurally robust Zr-MOFs as scaffolds to build highly conductive Zr-MOF/PPy composites via an inner-outer dual-modification approach,which involves the production of conducting polypyrrole(PPy)both within the confined nanoporous channels and the external surface of Zr-MOFs via post-synthetic modification.The interconnection of confined PPy and surface-lined PPy together leads to a consecutive and extensive conducting network to the maximum extent.This therefore entails outstanding conductivity up to~14.3 S cm^(-1) in Zr-MOF/PPy composites,which is approximately 1-2 orders of magnitude higher than that for conductive MOF nanocomposites constructed from either inner or outer modification.Benefiting from the strong and tunable conduction loss,as well as the induced dielectric polarization originated from the porous structures and MOF-polymer interfaces,Zr-MOF/PPy exhibits excellent microwave attenuation capabilities and a tunable absorption frequency range.Specifically,with only 15 wt.%loading,the minimum reflection loss(RLmin)can reach up to-67.4 dB,accompanied by an effective absorption bandwidth(EAB)extending to 6.74 GHz.Furthermore,the microwave absorption characteristics can be tailored from the C-band to the Ku-band by adjusting the loading of PPy.This work provides valuable insights into the fabrication of conductive MOF composites by presenting a straightforward pathway to enhance and reg-ulate electrical conduction in MOF-based nanocomposites,thus paving a way to facilely fabricate pristine MOF-based microwave absorbers.
基金supported by the PhD Start-up Fund of the Science and Technology Department of Liaoning Province(No.2022-BS-306)the General Cultivation Scientific Research Project of Bohai University(No.0522xn058)the PhD Research Startup Foundation of Bohai University(No.0521bs021).
文摘The preparation of electromagnetic(EM)wave absorption materials provided with the characteristics of thin matching thickness,broad bandwidth,and mighty absorption intensity is an efficient solution to current EM pollution.Herein,Graphene nanosheets(GN)were firstly fabricated via a facile high-energy ball milling method,subsequently high-purity 1T-MoS_(2) petals were uniformly anchored on the surface of GN to prepare 1T-MoS_(2)@GN nanocomposites.Plentiful multiple reflection and scattering of EM waves in a distinctive multidimensional structure formed by GN and 1T-MoS_(2),copious polarization loss consisting of interfacial polarization loss and dipolar polarization loss severally derived from multitudinous heterointerfaces and profuse electric dipoles in 1T-MoS_(2)@GN,and mighty conduction loss originated from plentiful induced current in 1T-MoS_(2)@GN generated via the migration of massive electrons,all of which endowed 1T-MoS_(2)@GN nanocomposites with exceptional EM wave absorption performances.The minimum reflection loss(RLmin)of 1T-MoS_(2)@GN reached–50.14 dB at a thickness of only 2.10 mm,and the effective absorption bandwidth(EAB)was up to 6.72 GHz at an ultra-thin matching thickness of 1.84 mm.Moreover,the radar scattering cross section(RCS)reduction value of 36.18 dB m2 at 0°could be achieved as well,which ulteriorly validated the tremendous potential of 1T-MoS_(2)@GN nanocomposites in practical applications.
基金support from the National Key Research and Development Program of China(No.2021YFB3701503)the Key Research and Development Program of Ningbo,China(No.2023Z107).
文摘As a novel 2D material,Ti_(3)C_(2)T_(x)-MXene has become a major area of interest in the field of microwave absorption(MA).However,the MA effect of common Ti_(3)C_(2)T_(x)-MXene is not prominent and often requires complex processes or combinations of other ma-terials to achieve enhanced performance.In this context,a kind of gradient woodpile structure using common Ti_(3)C_(2)T_(x)-MXene as MA ma-terial was designed and manufactured through direct ink writing(DIW)3D printing.The minimum reflection loss(RL_(min))of the Ti_(3)C_(2)T_(x)-MXene-based gradient woodpile structures with a thickness of less than 3 mm can reach-70 dB,showing considerable improve-ment compared with that of a completely filled structure.In addition,the effective absorption bandwidth(EAB)reaches 7.73 GHz.This study demonstrates that a Ti_(3)C_(2)T_(x)-MXene material with excellent MA performance and tunable frequency band can be successfully fab-ricated with a macroscopic structural design and through DIW 3D printing without complex material hybridization and modification,of-fering broad application prospects by reducing electromagnetic wave radiation and interference.
基金Anusandhan National Research Foundation (ANRF), Department of Science & Technology (DST), New Delhi, India under Ramanujan award (SB/S2/RJN-159/2017)。
文摘The rising concern over electromagnetic (EM) pollution is re-sponsible for the rapid progress in EM interference (EMI) shielding and EM wave absorption in the last few years, and carbon materials with a large sur-face area and high porosity have been investigated. Compared to other car-bon materials, biomass-derived carbon (BC) are considered efficient and eco-friendly materials for this purpose. We summarize the recent advances in BC materials for both EMI shielding and EM wave absorption. After a brief overview of the synthesis strategies of BC materials and a precise out-line of EM wave interference, strategies for improving their EMI shielding and EM wave absorption are discussed. Finally, the existing challenges and the future prospects for such materials are briefly summarized.
基金supported by the National Natural Science Foundation of China(No.62371222)the Defense Industrial Technology Development Program(No.JCKY2023605C002)thePriority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)and the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(No.ZHD202305).
文摘The intrinsic high magnetocrystalline anisotropy equivalent field can help the hexaferrites break through Snoek’s limit and increase the resonance frequency.This is advantageous for microwave absorption applications in the mid to low-frequency range of gigahertz.In this study,we prepared Z-type Ba_(3)Co_(1.6−x)Zn_(x)Cu_(0.4)Fe_(24)O_(41)hexaferrites using the sol-gel auto-combustion method.By changing the ratio of Co and Zn ions,the magnetocrystalline anisotropy of ferrite is further ma-nipulated,resulting in significant changes in their magnetic resonance frequency and intensity.Ba_(3)Zn_(1.6)Cu_(0.4)Fe_(24)O_(41)with high-frequency resonance achieved the lowest reflectivity of−72.18 dB at 15.56 GHz,while Ba_(3)Co_(1.5)Zn_(0.1)Cu_(0.4)Fe_(24)O_(41)with stronger loss obtained the widest bandwidth of 4.93 GHz(6.14-11.07).Additionally,we investigated surface wave suppression properties previously overlooked.Ba_(3)Co_(1.5)Zn_(0.1)Cu_(0.4)Fe_(24)O_(41)can achieve a larger attenuation at low frequency under low thickness,which has an excellent effect on reducing backscattering.This work provides a useful reference for the preparation and application of high-performance magnetic-loss materials.
基金supported by the National Natural Science Foundation of China(Nos.52122106 and 52027802)the“Pioneer”Research and Development Program of Zhejiang Province,China(No.2022C01230)+2 种基金the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering,China(No.2021SZ-FR005)the Space Application System of China Manned Space Program(No.KJZ-YY-NCL03)the opening fund of Key Laboratory of Rare Earths,Chinese Academy of Sciences。
文摘Interface modulation is an important pathway for highly efficient electromagnetic wave absorption.Herein,tailored interfaces between Fe_(3)O_(4)particles and the hexagonal-YFeO_(3)(h-YFeO_(3))framework were constructed via facile self-assembly.The resulting interfa-cial electron rearrangement at the heterojunction led to enhanced dielectric and magnetic loss synergy.Experimental results and density function theory(DFT)simulations demonstrate a transition in electrical properties from a half-metallic monophase to metallic Fe_(3)O_(4)/h-YFeO_(3)composites,emphasizing the advantages of the formed heterointerface.The transformation of electron behavior is also accompan-ied by a redistribution of electrons at the Fe_(3)O_(4)/h-YFeO_(3)heterojunction,leading to the accumulation of localized electrons around the Y-O-Fe band bridge,consequently enhancing the polarization.A minimum reflection loss of-34.0 dB can be achieved at 12.0 GHz and 2.0 mm thickness with an effective bandwidth of 3.3 GHz due to the abundant interfaces,enhanced polarization,and rational impedance.Thus,the synergistic effects endow the Fe_(3)O_(4)/h-YFeO_(3)composites with high performance and tunable functional properties for efficient electromagnetic absorption.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LQ22E030016)the National Natural Science Foundation of China(No.52275137)+1 种基金the China Postdoctoral Science Foundation(No.2022M722831)the Postdoctoral Research Selected Funding Project of Zhejiang Province,China(No.ZJ2022063).
文摘The development of high-performance functional composites has become a research hotspot in response to the hazards of over-heating and electromagnetic radiation in modern electronic devices.Herein,we grew magnetic Fe_(3)O_(4)particles in situ on the MXene layer to obtain an MXene@Fe_(3)O_(4)composite with rich heterogeneous interfaces.Owing to the unique heterostructure and the synergistic effects of multiple electromagnetic wave absorption mechanisms,the composite achieved a minimum reflection loss of-27.14 dB and an effect-ive absorption bandwidth of 2.05 GHz at an absorption thickness of 2 mm.Moreover,the MXene@Fe_(3)O_(4)composite could be encapsu-lated in thermoplastic polyurethane(TPU)via thermal curing.The obtained composite elastomer exhibited a strong tensile strength,and its thermal diffusivity was 113%higher than that of pure TPU.Such additional mechanical properties and thermal conduction features render this composite elastomer an advanced electromagnetic absorber to adapt to the ever-changing environment for expanding practical applications.
基金financially supported by Joint Funds of the National Natural Science Foundation of China(Nos.U23A20673,U22A20244,and 52478261)Qingchuang Technology Project(No.2021KJ045)+1 种基金the China Postdoctoral Science Foundation(No.2024M750580)the Key Laboratory of Functional Inorganic Material Chemistry(Heilongjiang University),Ministry of Education
文摘Carbon-based sponge materials have attracted massive attention as electromagnetic wave(EMW)absorber candidates due to their lightweight and excellent electromagnetic(EM)attenuation capability.However,the high cost,complex fabrication process and limited EMW absorption bandwidth restrict their application.Herein,a hierarchical threedimensional(3D)cotton derived carbon fibers coated with core–shell structure Fe Ni nanoparticle@porous carbon(CCF/Fe Ni@PC)from MOF precursor were successfully constructed by coprecipitation and one-step pyrolysis methods.By regulating carbonization temperature,optimizing the electromagnetic parameters,outstanding electromagnetic absorption(EMA)performance was achieved.The CCF@Fe Ni/PC synthesized at 900℃demonstrates a-64.5 d B minimum reflection loss(RL_(min))at 15.39 GHz,and the effective absorption bandwidth(EAB)is 5.08 GHz when the thickness is only1.9 mm.Notably,the maximum EAB(EAB_(max))was extended8.18 GHz at 2.96 mm for Fe Ni-800.The excellent microwave absorption performance is attributed to the synergistic effect of enhanced dielectric loss and magnetic loss,good impedance matching as well as hierarchical multiple scattering and reflection of EMWs.The obtained CCF@Fe Ni/PC composites provide a novel and promising strategy for constructing lightweight low-cost efficient microwave absorption materials.
