Realizing ultra-wideband absorption,desirable attenuation capability at high temperature and mechanical requirements for real-life applications remains a great challenge for microwave absorbing materials.Herein,we hav...Realizing ultra-wideband absorption,desirable attenuation capability at high temperature and mechanical requirements for real-life applications remains a great challenge for microwave absorbing materials.Herein,we have constructed a porous carbon fiber/polymethacrylimide(CP)structure for acquiring promising microwave absorption performance and withstanding both elevated temperature and high strength in a low density.Given the ability of porous structure to induce desirable impedance matching and multiple reflection,the absorption bandwidth of CP composite can reach ultra-wideband absorption of 14 GHz at room temperature and even cover the whole X-band at 473 K.Additionally,the presence of imide ring group in polymethacrylimide and hard bubble wall endows the composite with excellent heat and compressive behaviors.Besides,the lightweight of the CP composite with a density of only 110 mg cm^(−3) coupled with high compressive strength of 1.05 MPa even at 453 K also satisfies the requirements in engineering applica-tions.Compared with soft and compressible aerogel materials,we envision that the rigid porous foam absorbing material is particularly suitable for environmental extremes.展开更多
The development of multifunctional materials and synergistic applications of various functions are important conditions for integrated and miniaturized equipment.Here,we developed asymmetric MXene/aramid nanofibers/po...The development of multifunctional materials and synergistic applications of various functions are important conditions for integrated and miniaturized equipment.Here,we developed asymmetric MXene/aramid nanofibers/polyimides(AMAP)aerogels with different modules using an integrated molding process.Cleverly asymmetric modules(layered MXene/aramid nanofibers section and porous MXene/aramid nanofibers/polyimides section)interactions are beneficial for enhanced performances,resulting in low reflection electromagnetic interference(EMI)shielding(specific shielding effectiveness of 2483(dB·cm^(3))/g and a low R-value of 0.0138),high-efficiency infrared radiation(IR)stealth(ultra-low thermal conductivity of 0.045 W/(m·K)and IR emissivity of 0.32 at 3–5μm and 0.28 at 8–14μm),and excellent thermal management performances of insulated Joule heating.Furthermore,these multifunctional AMAP aerogels are suitable for various application scenarios such as personal and building protection against electromagnetic pollution and cold,as well as military equipment protection against infrared detection and EMI.展开更多
Magnetic metal absorbers exhibit remarkable microwave absorption capacity.However,their practical application is severely limited due to their susceptibility to corrosion,particularly in marine environ-ments.To addres...Magnetic metal absorbers exhibit remarkable microwave absorption capacity.However,their practical application is severely limited due to their susceptibility to corrosion,particularly in marine environ-ments.To address this challenge,we propose a novel approach involving the modification and control of FeCo/rGO microwave absorbers using rare earth lanthanum(La).This strategy aims to achieve both high-performance microwave absorption and enhanced resistance to marine corrosion.In this study,we employ a La_(2)O_(3) modifying control strategy to refine the FeCo magnetic particles and coat them with CoFe2O4 on the surface,leveraging the pinning effect of in situ generated La_(2)O_(3) .This process enhances the interface polarization of the absorbers,thereby improving their electromagnetic performance and ma-rine corrosion resistance.Consequently,the La_(2)O_(3) modified FeCo@rGO composites exhibit broadband ab-sorption,covering a wide frequency range of 6.11 GHz at 1.55 mm.Notably,the electromagnetic proper-ties of the La_(2)O_(3) modified FeCo@rGO absorbers remain stable even after prolonged exposure to a 3.5 wt%NaCI solution,simulating marine conditions,for at least 15 days.Furthermore,we perform first-principle calculations on FeCo and FeCo-O to validate the corrosion resistance of the La_(2)O_(3) modified FeCo@rGO composites at the atomic level.This comprehensive investigation explores the control of rare earth lan-thanum modification on the size of magnetic metal particles,enabling efficient electromagnetic wave absorption and marine corrosion resistance.The results of this study provide a novel and facile strategy for the control of microwave absorbers,offering promising prospects for future research and development in this field.展开更多
Integrated micro and nanostructures,heterogeneous components,defects,and interfaces is the way to develop high-performance microwave absorbing materials.However,there still needs to be more precise experimental routes...Integrated micro and nanostructures,heterogeneous components,defects,and interfaces is the way to develop high-performance microwave absorbing materials.However,there still needs to be more precise experimental routes and effective validation.In this work,by a continuous process of vacuum sintering,hydrothermal,and carbon thermal reduction,magnetic FeCo nanoparticles were successfully embedded on the hollow double-shell mesoporous SiC@C surface,thus solving the challenges of a single component loss mechanism.The hollow double-shell nanostructure introduces air to enhance impedance matching while significantly reducing the density of the material.The extensive defects and heterogeneous grain boundaries effectively enhance the polarization loss capacity.The magnetic loss mechanism introduced by the magnetic particles effectively improves the impedance matching properties of the material.The synergy of these multiple advantages has enabled the SCFC_(2)-8(here SiC@C@FeCo is abbreviated to SCFC,2 represents the initial metal ion content,and 8 represents the hydrothermal time)sample to achieve an adequate absorption bandwidth of 6.09 GHz at 2.0 mm.With a minimum reflection loss of-60.56 dB,the absorption bandwidth can cover the entire C,X,and Ku bands by adjusting the matching thickness(1.3–4.0 mm).This work provides a valuable paradigm for the deeper exploitation of microwave absorption potential and guides the development of other high-performance materials.展开更多
Achieving synergistic absorption of electromagnetic waves(EMWs)in the mid-high frequency and absorption band conversion is an urgent problem.However,the present solution is usually a straightforward mixture of magneti...Achieving synergistic absorption of electromagnetic waves(EMWs)in the mid-high frequency and absorption band conversion is an urgent problem.However,the present solution is usually a straightforward mixture of magnetic component-carbon component.Hereby,we optimize the magnetic properties and electrical relaxation response from a chemical synthesis perspective.Through integrated design,the contents of carbon components and multi-dimensional morphology are controlled by retaining strong magnetic properties.The morphology design and the construction of heterogeneous interfaces will boost the intense response of charge in the surrounding to enhance the polarization effect.The multi-dimensional structure and electromagnetic(EM)properties of the sample after optimized engineering have an extremely powerful absorption conversion effect on EMW energy.NiCo@C particles ultimately achieve synergistic absorption effects at low thickness(d<3.5 mm)at middle frequencies(6–10 GHz)and high frequencies(10.5–18 GHz).Our work establishes a correlation mechanism between the physical and chemical properties of materials and EM parameters.It also provides insight into the synergistic absorption of EMWs in the mid-high frequency and absorption band conversion strategies.展开更多
It is a challenge to design an absorber which can simultaneously satisfy comprehensive demands of broad absorption band,wide incident angle range,and low-profile.In this work,we designed a metamaterial absorber(MMA)ba...It is a challenge to design an absorber which can simultaneously satisfy comprehensive demands of broad absorption band,wide incident angle range,and low-profile.In this work,we designed a metamaterial absorber(MMA)based on the antenna reciprocity theory to achieve the above goals.Firstly,a three-dimensional(3D)propeller-like structure with reference to a typical magneto-electric dipole(MED)an-tenna was proposed and analyzed by the characteristic mode(CM)theory to realize near-omnidirectional radiation.Then,the radiation-absorption conversion was realized by introducing lossy materials into this structure,and the absorption performance was further improved by optimizing the dispersion feature of the lossy materials.Finally,the propeller-like metamaterial absorber with a thickness of 0.113λL was manufactured efficiently and integrally through 3D printing technology.Simulation results showed that the proposed absorber can achieve broadband absorption with the efficiency more than 90%in the fre-quency band of 3.4-10 GHz.It also has excellent wide-angle absorption capacity,with Transverse Electric(TE)polarization of 0°to 50°and Transverse Magnetic(TM)polarization of 0°to 80°.With the increase of incident angle,the upper limit of absorption bandwidth can be gradually extended to 18 GHz.Moreover,the effectiveness in the range of 0°to 60°incident angle is verified by measuring the reflectivity of the 3D printed absorber.展开更多
Regulating dielectric genes of hollow metal-organic frameworks is a milestone project for microwave absorption(MA).However,there is still a bottleneck in deciphering the contribution of various dielectric genes,making...Regulating dielectric genes of hollow metal-organic frameworks is a milestone project for microwave absorption(MA).However,there is still a bottleneck in deciphering the contribution of various dielectric genes,making it hard to expand the MA potential from selective encoding gene sequences.Herein,a custom-made proton tailoring strategy is used to build a controllable cavity,and meticulously designed thermodynamic regulation promotes the rearrangement of carbon atoms from disorder to order,thus enhancing the characteristics of charge transfer.Meanwhile,the defect-configuration transformation from heteroatom to vacancy and geometric configuration of hollow structure increase the polarization-related dielectric genes.Therefore,MA performance is enhanced towards broadband absorption(6.6 GHz,1.78 mm)and high-efficiency loss(-62.5 dB),making samples suitable for complex open electromagnetic environments.This work realizes the tradeoff between dielectric gene sequences and provides a profound insight into the functions and sources of various microwave loss mechanisms.展开更多
With the aim to obtain enhanced absorbing performance at small thickness and low filling,a robust strat-egy to fabricate zinc oxide(ZnO)modified carbon fiber(CF)structures have been successfully prepared by using low ...With the aim to obtain enhanced absorbing performance at small thickness and low filling,a robust strat-egy to fabricate zinc oxide(ZnO)modified carbon fiber(CF)structures have been successfully prepared by using low temperature hydrothermal method.Due to the multi-interface polarization caused by the high specific surface area of the complex heterostructures and the improvement of impedance matching,the composites show excellent electromagnetic wave absorption properties.Under the condition of low filling content(20 wt%)and ultra-thin thickness(1.5 mm),the excellent absorption performance of minimal reflection loss of−34.4 dB and an effective absorption bandwidth(RL≤−10 dB)of 4.94 GHz is achieved.In addition,the effective absorption bandwidth covers the whole 2-18 GHz band with the increase of thickness from 0.5 to 10 mm.This work provides an innovative method for designing the matching layer of carbon-based absorbing materials,and ZnO@CF heterostructure is expected to become a potential absorbing material.展开更多
基金supported by the National Natural Science Foundation of China(52172091 and 52172295)the Interdisciplinary Innovation Foundation for Graduates(Nanjing University of Aeronautics and Astronautics,No.KXKCXJJ202009).
文摘Realizing ultra-wideband absorption,desirable attenuation capability at high temperature and mechanical requirements for real-life applications remains a great challenge for microwave absorbing materials.Herein,we have constructed a porous carbon fiber/polymethacrylimide(CP)structure for acquiring promising microwave absorption performance and withstanding both elevated temperature and high strength in a low density.Given the ability of porous structure to induce desirable impedance matching and multiple reflection,the absorption bandwidth of CP composite can reach ultra-wideband absorption of 14 GHz at room temperature and even cover the whole X-band at 473 K.Additionally,the presence of imide ring group in polymethacrylimide and hard bubble wall endows the composite with excellent heat and compressive behaviors.Besides,the lightweight of the CP composite with a density of only 110 mg cm^(−3) coupled with high compressive strength of 1.05 MPa even at 453 K also satisfies the requirements in engineering applica-tions.Compared with soft and compressible aerogel materials,we envision that the rigid porous foam absorbing material is particularly suitable for environmental extremes.
基金supported by the National Key R&D Program of China(No.2021YFB3502500)the National Natural Science Foundation of China(Nos.52172091 and 52172295)+1 种基金Open Fund of Key Laboratory of Materials Preparation and Protection for Harsh Environment(Nanjing University of Aeronautics and Astronautics)Ministry of Industry and Information Technology(No.56XCA22042).
文摘The development of multifunctional materials and synergistic applications of various functions are important conditions for integrated and miniaturized equipment.Here,we developed asymmetric MXene/aramid nanofibers/polyimides(AMAP)aerogels with different modules using an integrated molding process.Cleverly asymmetric modules(layered MXene/aramid nanofibers section and porous MXene/aramid nanofibers/polyimides section)interactions are beneficial for enhanced performances,resulting in low reflection electromagnetic interference(EMI)shielding(specific shielding effectiveness of 2483(dB·cm^(3))/g and a low R-value of 0.0138),high-efficiency infrared radiation(IR)stealth(ultra-low thermal conductivity of 0.045 W/(m·K)and IR emissivity of 0.32 at 3–5μm and 0.28 at 8–14μm),and excellent thermal management performances of insulated Joule heating.Furthermore,these multifunctional AMAP aerogels are suitable for various application scenarios such as personal and building protection against electromagnetic pollution and cold,as well as military equipment protection against infrared detection and EMI.
基金National Key R&D Program of China(No.2021YFB3502500)National Natural Science Foundation of China(Nos.52172091 and 52172295)+3 种基金Natural Science Foundation of Jiangsu Province(No.BK20211199)Scientific Research Fund of AnHui Provincial Education Department(No.KJ2021A0034)Open Fund of Key Laboratory of Materials Preparation and Protection for Harsh Environment(Nanjing University of Aeronautics and Astronautics)Ministry of Industry and Information Technology(No.56XCA22042).
文摘Magnetic metal absorbers exhibit remarkable microwave absorption capacity.However,their practical application is severely limited due to their susceptibility to corrosion,particularly in marine environ-ments.To address this challenge,we propose a novel approach involving the modification and control of FeCo/rGO microwave absorbers using rare earth lanthanum(La).This strategy aims to achieve both high-performance microwave absorption and enhanced resistance to marine corrosion.In this study,we employ a La_(2)O_(3) modifying control strategy to refine the FeCo magnetic particles and coat them with CoFe2O4 on the surface,leveraging the pinning effect of in situ generated La_(2)O_(3) .This process enhances the interface polarization of the absorbers,thereby improving their electromagnetic performance and ma-rine corrosion resistance.Consequently,the La_(2)O_(3) modified FeCo@rGO composites exhibit broadband ab-sorption,covering a wide frequency range of 6.11 GHz at 1.55 mm.Notably,the electromagnetic proper-ties of the La_(2)O_(3) modified FeCo@rGO absorbers remain stable even after prolonged exposure to a 3.5 wt%NaCI solution,simulating marine conditions,for at least 15 days.Furthermore,we perform first-principle calculations on FeCo and FeCo-O to validate the corrosion resistance of the La_(2)O_(3) modified FeCo@rGO composites at the atomic level.This comprehensive investigation explores the control of rare earth lan-thanum modification on the size of magnetic metal particles,enabling efficient electromagnetic wave absorption and marine corrosion resistance.The results of this study provide a novel and facile strategy for the control of microwave absorbers,offering promising prospects for future research and development in this field.
基金supported by the National Key R&D Program of China(No.2021YFB3502500)the National Natural Science Foundation of China(Nos.52172091 and 52172295)+1 种基金Open Fund of Key Laboratory of Materials Preparation and Protection for Harsh Environment(Nanjing University of Aeronautics and Astronautics)Ministry of Industry and Information Technology(No.56XCA22042).
文摘Integrated micro and nanostructures,heterogeneous components,defects,and interfaces is the way to develop high-performance microwave absorbing materials.However,there still needs to be more precise experimental routes and effective validation.In this work,by a continuous process of vacuum sintering,hydrothermal,and carbon thermal reduction,magnetic FeCo nanoparticles were successfully embedded on the hollow double-shell mesoporous SiC@C surface,thus solving the challenges of a single component loss mechanism.The hollow double-shell nanostructure introduces air to enhance impedance matching while significantly reducing the density of the material.The extensive defects and heterogeneous grain boundaries effectively enhance the polarization loss capacity.The magnetic loss mechanism introduced by the magnetic particles effectively improves the impedance matching properties of the material.The synergy of these multiple advantages has enabled the SCFC_(2)-8(here SiC@C@FeCo is abbreviated to SCFC,2 represents the initial metal ion content,and 8 represents the hydrothermal time)sample to achieve an adequate absorption bandwidth of 6.09 GHz at 2.0 mm.With a minimum reflection loss of-60.56 dB,the absorption bandwidth can cover the entire C,X,and Ku bands by adjusting the matching thickness(1.3–4.0 mm).This work provides a valuable paradigm for the deeper exploitation of microwave absorption potential and guides the development of other high-performance materials.
基金supported by the National Key R&D Program of China(No.2021YFB3502500)and the National Natural Science Foundation of China(Nos.52172091 and 52172295)Open Fund of Key Laboratory of Materials Preparation and Protection for Harsh Environment(Nanjing University of Aeronautics and Astronautics)Ministry of Industry and Information Technology(No.56XCA22042)。
文摘Achieving synergistic absorption of electromagnetic waves(EMWs)in the mid-high frequency and absorption band conversion is an urgent problem.However,the present solution is usually a straightforward mixture of magnetic component-carbon component.Hereby,we optimize the magnetic properties and electrical relaxation response from a chemical synthesis perspective.Through integrated design,the contents of carbon components and multi-dimensional morphology are controlled by retaining strong magnetic properties.The morphology design and the construction of heterogeneous interfaces will boost the intense response of charge in the surrounding to enhance the polarization effect.The multi-dimensional structure and electromagnetic(EM)properties of the sample after optimized engineering have an extremely powerful absorption conversion effect on EMW energy.NiCo@C particles ultimately achieve synergistic absorption effects at low thickness(d<3.5 mm)at middle frequencies(6–10 GHz)and high frequencies(10.5–18 GHz).Our work establishes a correlation mechanism between the physical and chemical properties of materials and EM parameters.It also provides insight into the synergistic absorption of EMWs in the mid-high frequency and absorption band conversion strategies.
基金supported by the Ministry of Industry and Information Technology (No.56XCA22042)the Priority Aca-demic Program Development of Jiangsu Higher Education Institu-tions (PAPD)the Fundamental Research Funds for the Central Universities,Jiangsu Provincial Key Laboratory of Advanced Manipulating Technique of Electromagnetic Wave and Open Fund of Key Laboratory of Materials Preparation and Protection for Harsh Environment (Nanjing University of Aeronautics and Astronautics).
文摘It is a challenge to design an absorber which can simultaneously satisfy comprehensive demands of broad absorption band,wide incident angle range,and low-profile.In this work,we designed a metamaterial absorber(MMA)based on the antenna reciprocity theory to achieve the above goals.Firstly,a three-dimensional(3D)propeller-like structure with reference to a typical magneto-electric dipole(MED)an-tenna was proposed and analyzed by the characteristic mode(CM)theory to realize near-omnidirectional radiation.Then,the radiation-absorption conversion was realized by introducing lossy materials into this structure,and the absorption performance was further improved by optimizing the dispersion feature of the lossy materials.Finally,the propeller-like metamaterial absorber with a thickness of 0.113λL was manufactured efficiently and integrally through 3D printing technology.Simulation results showed that the proposed absorber can achieve broadband absorption with the efficiency more than 90%in the fre-quency band of 3.4-10 GHz.It also has excellent wide-angle absorption capacity,with Transverse Electric(TE)polarization of 0°to 50°and Transverse Magnetic(TM)polarization of 0°to 80°.With the increase of incident angle,the upper limit of absorption bandwidth can be gradually extended to 18 GHz.Moreover,the effectiveness in the range of 0°to 60°incident angle is verified by measuring the reflectivity of the 3D printed absorber.
文摘Regulating dielectric genes of hollow metal-organic frameworks is a milestone project for microwave absorption(MA).However,there is still a bottleneck in deciphering the contribution of various dielectric genes,making it hard to expand the MA potential from selective encoding gene sequences.Herein,a custom-made proton tailoring strategy is used to build a controllable cavity,and meticulously designed thermodynamic regulation promotes the rearrangement of carbon atoms from disorder to order,thus enhancing the characteristics of charge transfer.Meanwhile,the defect-configuration transformation from heteroatom to vacancy and geometric configuration of hollow structure increase the polarization-related dielectric genes.Therefore,MA performance is enhanced towards broadband absorption(6.6 GHz,1.78 mm)and high-efficiency loss(-62.5 dB),making samples suitable for complex open electromagnetic environments.This work realizes the tradeoff between dielectric gene sequences and provides a profound insight into the functions and sources of various microwave loss mechanisms.
基金supported by the National Natural Science Foundation of China(No.51702158)the Open Fund of Key Laboratory of Materials Preparation and Protection for Harsh Environment(Nanjing University of Aeronautics and Astronautics),Ministry of Industry and Information Technology(No.56XCA20013-5)the Interdisciplinary Innovation Fundation for Graduates(Nanjing University of Aeronautics and Astronautics,No.KXKCXJJ202009).
文摘With the aim to obtain enhanced absorbing performance at small thickness and low filling,a robust strat-egy to fabricate zinc oxide(ZnO)modified carbon fiber(CF)structures have been successfully prepared by using low temperature hydrothermal method.Due to the multi-interface polarization caused by the high specific surface area of the complex heterostructures and the improvement of impedance matching,the composites show excellent electromagnetic wave absorption properties.Under the condition of low filling content(20 wt%)and ultra-thin thickness(1.5 mm),the excellent absorption performance of minimal reflection loss of−34.4 dB and an effective absorption bandwidth(RL≤−10 dB)of 4.94 GHz is achieved.In addition,the effective absorption bandwidth covers the whole 2-18 GHz band with the increase of thickness from 0.5 to 10 mm.This work provides an innovative method for designing the matching layer of carbon-based absorbing materials,and ZnO@CF heterostructure is expected to become a potential absorbing material.
