Infrared metamaterial absorber(MMA) based on metal-insulator-metal(MIM) configuration with flexible design,perfect and selective absorption,has attracted much attention recently for passive radiative cooling applicati...Infrared metamaterial absorber(MMA) based on metal-insulator-metal(MIM) configuration with flexible design,perfect and selective absorption,has attracted much attention recently for passive radiative cooling applications.To cool objects passively,broadband infrared absorption(i.e.8-14 μm) is desirable to emit thermal energy through atmosphere window.We present a novel MMA composed of multilayer MIM resonators periodically arranged on a PbTe/MgF_(2) bilayer substrate.Verified by the rigorous coup led-wave analysis method,the proposed MMA shows a relative bandwidth of about 45%(from 8.3 to 13.1 μm with the absorption intensity over 0.8).The broadband absorption performs stably over a wide incident angle range(below 50°) and predicts 12 K cooling below ambient temperature at nighttime.Compared with the previous passive radiative coolers,our design gets rid of the continuous metal substrate and provides an almost ideal transparency window(close to 100%)for millimeter waves over 1 mm.The structure is expected to have potential applications in thermal control of integrated devices,where millimeter wave signal compatibility is also required.展开更多
Emulating synaptic plasticity in an artificial neural network is crucial to mimic the basic functions of the human brain.In this work,we report a new optoelectronic resistive random access memory(ORRAM)in a three-laye...Emulating synaptic plasticity in an artificial neural network is crucial to mimic the basic functions of the human brain.In this work,we report a new optoelectronic resistive random access memory(ORRAM)in a three-layer vertical heterostructure of graphene/Cd Se quantum dots(QDs)/graphene,which shows non-volatile multi-level optical memory under optical stimuli,giving rise to light-tunable synaptic behaviors.The optical non-volatile storage time is up to^450 s.The device realizes the function of multi-level optical storage through the interlayer changes between graphene and QDs.This work highlights the feasibility for applying two-dimensional(2D)materials in ORRAM and optoelectronic synaptic devices towards artificial vision.展开更多
Two-dimensional ferromagnetic van der Waals(2D vdW)heterostructures have opened new avenues for creating artificial materials with unprecedented electrical and optical functions beyond the reach of isolated 2D atomic ...Two-dimensional ferromagnetic van der Waals(2D vdW)heterostructures have opened new avenues for creating artificial materials with unprecedented electrical and optical functions beyond the reach of isolated 2D atomic layered materials,and for manipulating spin degree of freedom at the limit of few atomic layers,which empower next-generation spintronic and memory devices.However,to date,the electronic properties of 2D ferromagnetic heterostructures still remain elusive.Here,we report an unambiguous magnetoresistance behavior in CrI_(3)/graphene heterostructures,with a maximum magnetoresistance ratio of 2.8%.The magnetoresistance increases with increasing magnetic field,which leads to decreasing carrier densities through Lorentz force,and decreases with the increase of the bias voltage.This work highlights the feasibilities of applying two-dimensional ferromagnetic vdW heterostructures in spintronic and memory devices.展开更多
The increasing demands for electronic devices to achieve high miniaturization,functional integration,and wide bandwidth will exacerbate the heat generation and electromagnetic interference,which hinders the further de...The increasing demands for electronic devices to achieve high miniaturization,functional integration,and wide bandwidth will exacerbate the heat generation and electromagnetic interference,which hinders the further development of electronic devices.Therefore,both the issues of microwave absorption and heat dissipation of materials need to be addressed simultaneously.Herein,a multifunctional composite material is proposed by periodic arrangement of copper pillars in a matrix,based on the wave-absorbing material.As a result,the equivalent thermal conductivity of the composite structure is nearly 35 times higher than the wave-absorbing matrix,with the area filling proportion of the thermal conductivity material being 3.14%.Meanwhile,the reflectivity of the composite structure merely changes from-15.05 d B to-13.70 d B.It is proved that the designed composite structure possesses both high thermal conduction and strong microwave absorption.The measured results accord well with the simulation results,which demonstrates that the thermal conductivity of the composite structure can reach more than 10 W·m^(-1)·K^(-1)without significant deterioration of the absorption performance.展开更多
Since the beginning of research on two-dimensional(2D)materials,a few numbers of 2D ferroelectric materials have been predicted or experimentally confirmed,but 2D ferroelectrics as necessary functional materials are g...Since the beginning of research on two-dimensional(2D)materials,a few numbers of 2D ferroelectric materials have been predicted or experimentally confirmed,but 2D ferroelectrics as necessary functional materials are greatly important in developing future electronic devices.Recent breakthroughs in 2D ferroelectric materials are impressive,and the physical and structural properties of twisted 2D ferroelectrics,a new type of ferroelectric structure by rotating alternating monolayers to form an angle with each other,have attracted widespread interest and discussion.Here,we review the latest research on twisted 2D ferroelectrics,including Bernal-stacked bilayer graphene/BN,bilayer boron nitride,and transition metal dichalcogenides.Finally,we prospect the development of twisted 2D ferroelectrics and discuss the challenges and future of 2D ferroelectric materials.展开更多
Zero-index metamaterials(ZIMs)feature a uniform electromagnetic mode over a large area in arbitrary shapes,enabling many applications including high-transmission supercouplers with arbitrary shapes,directionindependen...Zero-index metamaterials(ZIMs)feature a uniform electromagnetic mode over a large area in arbitrary shapes,enabling many applications including high-transmission supercouplers with arbitrary shapes,directionindependent phase matching for nonlinear optics,and collective emission of many quantum emitters.However,most ZIMs reported to date are passive;active ZIMs that allow for dynamic modulation of their electromagnetic properties have rarely been reported.Here,we design and fabricate a magnetically tunable ZIM consisting of yttrium iron garnet(YIG)pillars sandwiched between two copper clad laminates in the microwave regime.By harnessing the Cotton–Mouton effect of YIG,the metamaterial was successfully toggled between gapless and bandgap states,leading to a“phase transition”between a zero-index phase and a single negative phase of the metamaterial.Using an S-shaped ZIM supercoupler,we experimentally demonstrated a tunable supercoupling state with a low intrinsic loss of 0.95 d B and a high extinction ratio of up to 30.63 d B at 9 GHz.We have also engineered a transition between the supercoupling state and the topological one-way transmission state at10.6 GHz.Our work enables dynamic modulation of the electromagnetic characteristics of ZIMs,enabling various applications in tunable linear,nonlinear,quantum,and nonreciprocal electromagnetic devices.展开更多
Developing highly efficient magnetic microwave absorb-ers(MAs)is crucial,and yet challenging for anti-corrosion properties in extremely humid and salt-induced foggy environments.Herein,a dual-oxide shell of ZnO/Al_(2)...Developing highly efficient magnetic microwave absorb-ers(MAs)is crucial,and yet challenging for anti-corrosion properties in extremely humid and salt-induced foggy environments.Herein,a dual-oxide shell of ZnO/Al_(2)O_(3) as a robust barrier to FeSiAl core is introduced to mitigate corrosion resistance.The FeSiAl@ZnO@Al_(2)O_(3) layer by layer hybrid structure is realized with atomic-scale precision through the atomic layer deposition technique.Owing to the unique hybrid structure,the FeSiAl@ZnO@Al_(2)O_(3) exhibits record-high micro-wave absorbing performance in low-frequency bands covering L and S bands with a minimum reflection loss(RLmin)of-50.6 dB at 3.4 GHz.Compared with pure FeSiAl(RLmin of-13.5 dB,a bandwidth of 0.5 GHz),the RLmin value and effective bandwidth of this designed novel absorber increased up to~3.7 and~3 times,respectively.Fur-thermore,the inert ceramic dual-shells have improved 9.0 times the anti-corrosion property of FeSiAl core by multistage barriers towards corrosive medium and obstruction of the electric circuit.This is attributed to the large charge transfer resistance,increased impedance modulus|Z|0.01 Hz,and frequency time constant of FeSiAl@ZnO@Al_(2)O_(3).The research demonstrates a promising platform toward the design of next-generation MAs with improved anti-corrosion properties.展开更多
The discoveries of ferromagnetic and ferroelectric two-dimensional(2D)materials have dramatically inspired intense interests due to their potential in the field of spintronic and nonvolatile memories.This review focus...The discoveries of ferromagnetic and ferroelectric two-dimensional(2D)materials have dramatically inspired intense interests due to their potential in the field of spintronic and nonvolatile memories.This review focuses on the latest 2D ferromagnetic and ferroelectric materials that have been most recently studied,including insulating ferromagnetic,metallic ferromagnetic,antiferromagnetic and ferroelectric 2D materials.The fundamental properties that lead to the long-range magnetic orders of 2D materials are discussed.The low Curie temperature(Tc)and instability in 2D systems limits their use in practical applications,and several strategies to address this constraint are proposed,such as gating and composition stoichiometry.A van der Waals(vdW)heterostructure comprising 2D ferromagnetic and ferroelectric materials will open a door to exploring exotic physical phenomena and achieve multifunctional or nonvolatile devices.展开更多
In this study,tri-rutile type Mg_(0.5)Ti_(0.5)TaO_(4) ceramics were synthesized,where the structure–property relationship,especially the structural configuration and intrinsic dielectric origin of Mg_(0.5)Ti_(0.5)TaO...In this study,tri-rutile type Mg_(0.5)Ti_(0.5)TaO_(4) ceramics were synthesized,where the structure–property relationship,especially the structural configuration and intrinsic dielectric origin of Mg_(0.5)Ti_(0.5)TaO_(4) ceramics,and the low-firing characteristics were studied.It is found that the tri-rutile structural type is unambiguously identified through the Rietveld refinement analysis,the selected area electron diffraction(SAED),and the high-resolution transmission electron microscopy(HRTEM)along the[110]zone axis.With the increase in sintering temperature,the densification and uniformity of crystal growth play important roles in regulating the microwave dielectric properties of Mg_(0.5)Ti_(0.5)TaO_(4) ceramics.Intrinsically,theoretical dielectric properties calculated by the far-infrared reflective spectra approached the experimental values,indicating the importance of structural features to dielectric properties.Furthermore,a glass additive with high matching relevance with ceramics has been developed to decrease the high sintering temperature of Mg_(0.5)Ti_(0.5)TaO_(4) ceramics,where 2–4 wt%Li_(2)O–MgO–ZnO–B_(2)O_(3)–SiO_(2)(LMZBS)glass frit was adopted to reduce the suitable temperature from 1275 to 1050℃ without significantly deteriorating the microwave dielectric characteristics.Specifically,Mg_(0.5)Ti_(0.5)TaO_(4) ceramics containing 2 wt% glass addition sintered at 1050℃for 4 h possess excellent microwave dielectric properties:dielectric constant(ε_(r))=44.3,quality factor multiplied by resonant frequency(Q×f)=23,820 GHz(f=6.2 GHz),and the temperature coefficient of resonant frequency(τ_(f))=123.2 ppm/℃.展开更多
Electromagnetic absorbing materials may convert electromagnetic energy into heat energy and dissipate it.However,in a high-power electromagnetic radiation environment,the temperature of the absorbing material rises si...Electromagnetic absorbing materials may convert electromagnetic energy into heat energy and dissipate it.However,in a high-power electromagnetic radiation environment,the temperature of the absorbing material rises significantly and even burns.It becomes critical to ensure electromagnetic absorption performance while minimizing temperature rise.Here,we systematically study the coupling mechanism between the electromagnetic field and the temperature field when the absorbing material is irradiated by electromagnetic waves.We find out the influence of the constitutive parameters of the absorbing materials(including uniform and non-uniform)on the temperature distribution.Finally,through a smart design,we achieve better absorption and lower temperature simultaneously.The accuracy of the model is affirmed as simulation results aligned with theoretical analysis.This work provides a new avenue to control the temperature distribution of absorbing materials.展开更多
Environmentally-friendly magnetic metallic absorbers with high-performing antioxidant property,thermal stability,and anticorrosion capability have attracted great attention in real-world applications.A surface modific...Environmentally-friendly magnetic metallic absorbers with high-performing antioxidant property,thermal stability,and anticorrosion capability have attracted great attention in real-world applications.A surface modification technology of magnetic metallic absorbers with dense and inert materials has been an effective strategy to solve the aforesaid problem.Herein,fluorinefree core–shell carbonyl iron-organic silicon absorbers(CI@SiO_(2)/1,1,1,3,3,3-hexamethyl disilazane(HMDS))were fabricated via a facile one-pot synthesis using tetraethyl orthosilicate(TEOS)and HMDS as the precursor of protective layer(SiO_(2)/HMDS),and CI@SiO_(2)/HMDS hybrid reveals its long-term corrosion resistance and excellent microwave absorption performance with a minimum reflection loss value of−44.3 dB and an effective absorption bandwidth of 5.3 GHz at a thin thickness of 2.0 mm after immersion in 5.0 wt.%NaCl acidic solutions for 2,160 h.Meanwhile,CI@SiO_(2)/HMDS hybrid can still achieve the maximum radar cross-sectional(RCS)reduction values about 16.5 dB·m^(2) at the detectionθof 0°.The exceptional microwave absorption performance and structural stability are largely due to the extraordinary wave-transparent property and shielding ability against corrosive medium of SiO_(2)/HMDS hydrophobic protective layer with a contact angle of 132.5°.The research paves the way for the large-scale and batch production of high-performance magnetic metallic absorbers and increases their survivability and reliability in the harsh environments.展开更多
The explosive process of 5G communication evokes the urgent demand of miniaturized and integrated dielectric ceramics filter It is a pressing need to advance the development of dielectric ceramics utilization of emerg...The explosive process of 5G communication evokes the urgent demand of miniaturized and integrated dielectric ceramics filter It is a pressing need to advance the development of dielectric ceramics utilization of emerging technology to design new materials and understand the polarization mechanism.This review provides the summary of the study of microwave dielectric ceramics(MWDCs)sintered higher than 1000℃ from 2010 up to now,with the purpose of taking a broad and historical view of these ceramics and illustrating research directions.To date,researchers endeavor to explain the structure-property relationship of ceramics with multitude of approaches and design a new formula or strategy to obtain excellent microwave dielectric properties.There are variety of factors that impact the permittivity,dielectric loss,and temperature stability of dielectric materials,covering intrinsic and extrinsic factors.Many of these factors are often intertwined,which can complicate new dielectric material discovery and the mechanism investigation.Because of the various ceramics systems,pseudo phase diagram was used to classify the dielectric materials based on the composition.In this review,the ceramics were firstly divided into ternary systems,and then brief description of the experimental probes and complementary theoretical methods that have been used to discern the intrinsic polarization mechanisms and the origin of intrinsic loss was mentioned.Finally,some perspectives on the future outlook for high-temperature MWDCs were offered based on the synthesis method,characterization techniques,and significant theory developments.展开更多
This article presents low-firing,low-loss and temperature stable ZnO-TiO_(2)-Nb_(2)O_(5) microwave dielectric composite ceramics with the assistance of lithium borosilicate(LBS)and zinc borosilicate(ZBS)glass frits.Th...This article presents low-firing,low-loss and temperature stable ZnO-TiO_(2)-Nb_(2)O_(5) microwave dielectric composite ceramics with the assistance of lithium borosilicate(LBS)and zinc borosilicate(ZBS)glass frits.There is a liquid phase(eutectic mixture)generated by LBS(ZBS)glass,and solid particles could be wetted and dissolved.Therefore,the migrations and rearrangements of particles could be performed.Besides,compared with ceramics undoped with glass frits,lower activation energies(E_(a))of ceramics doped with LBS and ZBS glass suggest that the low-temperature sintering behavior is easier to carry out.The results indicated that LBS and ZBS glass both are effective sintering aids to accelerate the sintering process and improve the microwave dielectric properties of composite ceramics by controlling the phase compositions under low temperature.Combination great properties of ZnO-TiO_(2)-Nb_(2)O_(5) ceramics were obtained when sintered at 900℃ for 4 h:ε_(r)=36.7,Q×f=20,000 GHz,τ_(f)=7 ppm/℃.展开更多
Although plasmonic nanostructure has attracted widespread research interest in recent years, it is still a major challenge to realize large-scale active plasmonic nanostructure operation in the visible optical frequen...Although plasmonic nanostructure has attracted widespread research interest in recent years, it is still a major challenge to realize large-scale active plasmonic nanostructure operation in the visible optical frequency. Herein,we demonstrate a heterostructure geometry comprising a centimeter-scale Au nanoparticle monolayer and VO_2 films, in which the plasmonic peak is inversely tuned between 685 nm and 618 nm by a heating process since the refractive index will change when VO_2 films undergo the transition between the insulating phase and the metallic phase. Simultaneously, the phase transition of VO_2 films can be improved by plasmonic arrays due to plasmonic enhanced light absorption and the photothermal effect. The phase transition temperature for Au∕VO_2 films is lower than that for bare VO_2 films and can decrease to room temperature under the laser irradiation. For lightinduced phase transition of VO_2 films, the laser power of Au∕VO_2 film phase transition is ~28.6% lower than that of bare VO_2 films. Our work raises the feasibility to use active plasmonic arrays in the visible region.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.52022018 and 52021001)the Program for Changjiang Scholars and Innovative Research Team in University。
文摘Infrared metamaterial absorber(MMA) based on metal-insulator-metal(MIM) configuration with flexible design,perfect and selective absorption,has attracted much attention recently for passive radiative cooling applications.To cool objects passively,broadband infrared absorption(i.e.8-14 μm) is desirable to emit thermal energy through atmosphere window.We present a novel MMA composed of multilayer MIM resonators periodically arranged on a PbTe/MgF_(2) bilayer substrate.Verified by the rigorous coup led-wave analysis method,the proposed MMA shows a relative bandwidth of about 45%(from 8.3 to 13.1 μm with the absorption intensity over 0.8).The broadband absorption performs stably over a wide incident angle range(below 50°) and predicts 12 K cooling below ambient temperature at nighttime.Compared with the previous passive radiative coolers,our design gets rid of the continuous metal substrate and provides an almost ideal transparency window(close to 100%)for millimeter waves over 1 mm.The structure is expected to have potential applications in thermal control of integrated devices,where millimeter wave signal compatibility is also required.
基金financial support from National Science Foundation of China(51602040,51872039)Science and Technology Program of Sichuan(M112018JY0025)Scientific Research Foundation for New Teachers of UESTC(A03013023601007)。
文摘Emulating synaptic plasticity in an artificial neural network is crucial to mimic the basic functions of the human brain.In this work,we report a new optoelectronic resistive random access memory(ORRAM)in a three-layer vertical heterostructure of graphene/Cd Se quantum dots(QDs)/graphene,which shows non-volatile multi-level optical memory under optical stimuli,giving rise to light-tunable synaptic behaviors.The optical non-volatile storage time is up to^450 s.The device realizes the function of multi-level optical storage through the interlayer changes between graphene and QDs.This work highlights the feasibility for applying two-dimensional(2D)materials in ORRAM and optoelectronic synaptic devices towards artificial vision.
基金Project supported by the National Natural Science Foundation of China(Grant No.51872039)Science and Technology Program of Sichuan,China(Grant No.M112018JY0025).
文摘Two-dimensional ferromagnetic van der Waals(2D vdW)heterostructures have opened new avenues for creating artificial materials with unprecedented electrical and optical functions beyond the reach of isolated 2D atomic layered materials,and for manipulating spin degree of freedom at the limit of few atomic layers,which empower next-generation spintronic and memory devices.However,to date,the electronic properties of 2D ferromagnetic heterostructures still remain elusive.Here,we report an unambiguous magnetoresistance behavior in CrI_(3)/graphene heterostructures,with a maximum magnetoresistance ratio of 2.8%.The magnetoresistance increases with increasing magnetic field,which leads to decreasing carrier densities through Lorentz force,and decreases with the increase of the bias voltage.This work highlights the feasibilities of applying two-dimensional ferromagnetic vdW heterostructures in spintronic and memory devices.
文摘The increasing demands for electronic devices to achieve high miniaturization,functional integration,and wide bandwidth will exacerbate the heat generation and electromagnetic interference,which hinders the further development of electronic devices.Therefore,both the issues of microwave absorption and heat dissipation of materials need to be addressed simultaneously.Herein,a multifunctional composite material is proposed by periodic arrangement of copper pillars in a matrix,based on the wave-absorbing material.As a result,the equivalent thermal conductivity of the composite structure is nearly 35 times higher than the wave-absorbing matrix,with the area filling proportion of the thermal conductivity material being 3.14%.Meanwhile,the reflectivity of the composite structure merely changes from-15.05 d B to-13.70 d B.It is proved that the designed composite structure possesses both high thermal conduction and strong microwave absorption.The measured results accord well with the simulation results,which demonstrates that the thermal conductivity of the composite structure can reach more than 10 W·m^(-1)·K^(-1)without significant deterioration of the absorption performance.
基金the financial support from National Science Foundation of China(51872039,52021001,5197204)。
文摘Since the beginning of research on two-dimensional(2D)materials,a few numbers of 2D ferroelectric materials have been predicted or experimentally confirmed,but 2D ferroelectrics as necessary functional materials are greatly important in developing future electronic devices.Recent breakthroughs in 2D ferroelectric materials are impressive,and the physical and structural properties of twisted 2D ferroelectrics,a new type of ferroelectric structure by rotating alternating monolayers to form an angle with each other,have attracted widespread interest and discussion.Here,we review the latest research on twisted 2D ferroelectrics,including Bernal-stacked bilayer graphene/BN,bilayer boron nitride,and transition metal dichalcogenides.Finally,we prospect the development of twisted 2D ferroelectrics and discuss the challenges and future of 2D ferroelectric materials.
基金Ministry of Science and Technology of the People's Republic of China(2021YFA1401000,2021YFB2801600)National Natural Science Foundation of China(51972044,52021001,62075114,U22A20148)+3 种基金Zhuhai Industry-University Research Collaboration Project(ZH22017001210108PWC)Beijing Municipal Natural Science Foundation(4212050,Z220008)Fundamental Research Funds for the Central Universities(ZYGX2020J005)Sichuan Provincial Science and Technology Department(2019YFH0154,2021YFSY0016,99203070)。
文摘Zero-index metamaterials(ZIMs)feature a uniform electromagnetic mode over a large area in arbitrary shapes,enabling many applications including high-transmission supercouplers with arbitrary shapes,directionindependent phase matching for nonlinear optics,and collective emission of many quantum emitters.However,most ZIMs reported to date are passive;active ZIMs that allow for dynamic modulation of their electromagnetic properties have rarely been reported.Here,we design and fabricate a magnetically tunable ZIM consisting of yttrium iron garnet(YIG)pillars sandwiched between two copper clad laminates in the microwave regime.By harnessing the Cotton–Mouton effect of YIG,the metamaterial was successfully toggled between gapless and bandgap states,leading to a“phase transition”between a zero-index phase and a single negative phase of the metamaterial.Using an S-shaped ZIM supercoupler,we experimentally demonstrated a tunable supercoupling state with a low intrinsic loss of 0.95 d B and a high extinction ratio of up to 30.63 d B at 9 GHz.We have also engineered a transition between the supercoupling state and the topological one-way transmission state at10.6 GHz.Our work enables dynamic modulation of the electromagnetic characteristics of ZIMs,enabling various applications in tunable linear,nonlinear,quantum,and nonreciprocal electromagnetic devices.
基金financially supported by the National Natural Science Foundation of China(No.51972045,5197021414)the Fundamental Research Funds for the Chinese Central Universities,China(No.ZYGX2019J025)+4 种基金Sichuan Science and Technology Program(No.2020JDRC0015 and No.2020JDRC0045)Sichuan Science and Technology Innovation Talent Project(No.2021JDRC0021)the Vice-Chancellor fellowship scheme at RMIT Universitythe RMIT Micro Nano Research Facility(MNRF)in the Victorian node of the Australian National Fabrication Facility(ANFF)the RMIT Microscopy and Microanalysis Facility(RMMF)to support this work。
文摘Developing highly efficient magnetic microwave absorb-ers(MAs)is crucial,and yet challenging for anti-corrosion properties in extremely humid and salt-induced foggy environments.Herein,a dual-oxide shell of ZnO/Al_(2)O_(3) as a robust barrier to FeSiAl core is introduced to mitigate corrosion resistance.The FeSiAl@ZnO@Al_(2)O_(3) layer by layer hybrid structure is realized with atomic-scale precision through the atomic layer deposition technique.Owing to the unique hybrid structure,the FeSiAl@ZnO@Al_(2)O_(3) exhibits record-high micro-wave absorbing performance in low-frequency bands covering L and S bands with a minimum reflection loss(RLmin)of-50.6 dB at 3.4 GHz.Compared with pure FeSiAl(RLmin of-13.5 dB,a bandwidth of 0.5 GHz),the RLmin value and effective bandwidth of this designed novel absorber increased up to~3.7 and~3 times,respectively.Fur-thermore,the inert ceramic dual-shells have improved 9.0 times the anti-corrosion property of FeSiAl core by multistage barriers towards corrosive medium and obstruction of the electric circuit.This is attributed to the large charge transfer resistance,increased impedance modulus|Z|0.01 Hz,and frequency time constant of FeSiAl@ZnO@Al_(2)O_(3).The research demonstrates a promising platform toward the design of next-generation MAs with improved anti-corrosion properties.
基金the National Natural Science Foundation of China(Nos.51602040 and 51872039)Science and Technology Program of Sichuan(No.M112018JY0025)Scientific Research Foundation for New Teachers of UESTC(No.A03013023601007).
文摘The discoveries of ferromagnetic and ferroelectric two-dimensional(2D)materials have dramatically inspired intense interests due to their potential in the field of spintronic and nonvolatile memories.This review focuses on the latest 2D ferromagnetic and ferroelectric materials that have been most recently studied,including insulating ferromagnetic,metallic ferromagnetic,antiferromagnetic and ferroelectric 2D materials.The fundamental properties that lead to the long-range magnetic orders of 2D materials are discussed.The low Curie temperature(Tc)and instability in 2D systems limits their use in practical applications,and several strategies to address this constraint are proposed,such as gating and composition stoichiometry.A van der Waals(vdW)heterostructure comprising 2D ferromagnetic and ferroelectric materials will open a door to exploring exotic physical phenomena and achieve multifunctional or nonvolatile devices.
基金support from the open research fund of Songshan Lake Materials Laboratory (No.2022SLABFN20)the Qinchuangyuan Citing Highlevel Innovation and Entrepreneurship Talent Projects (No.QCYRCXM-2022-40)+3 种基金the Natural Science Basic Research Program of Shaanxi (No.2022JQ-390)the National Natural Science Foundation of China (No.52102123)the National Key R&D Program of China (No.2022YFB2807405)the Natural Science Foundation of Sichuan Province (Nos.22NSFSC1973 and 2022NSFSC1959).
文摘In this study,tri-rutile type Mg_(0.5)Ti_(0.5)TaO_(4) ceramics were synthesized,where the structure–property relationship,especially the structural configuration and intrinsic dielectric origin of Mg_(0.5)Ti_(0.5)TaO_(4) ceramics,and the low-firing characteristics were studied.It is found that the tri-rutile structural type is unambiguously identified through the Rietveld refinement analysis,the selected area electron diffraction(SAED),and the high-resolution transmission electron microscopy(HRTEM)along the[110]zone axis.With the increase in sintering temperature,the densification and uniformity of crystal growth play important roles in regulating the microwave dielectric properties of Mg_(0.5)Ti_(0.5)TaO_(4) ceramics.Intrinsically,theoretical dielectric properties calculated by the far-infrared reflective spectra approached the experimental values,indicating the importance of structural features to dielectric properties.Furthermore,a glass additive with high matching relevance with ceramics has been developed to decrease the high sintering temperature of Mg_(0.5)Ti_(0.5)TaO_(4) ceramics,where 2–4 wt%Li_(2)O–MgO–ZnO–B_(2)O_(3)–SiO_(2)(LMZBS)glass frit was adopted to reduce the suitable temperature from 1275 to 1050℃ without significantly deteriorating the microwave dielectric characteristics.Specifically,Mg_(0.5)Ti_(0.5)TaO_(4) ceramics containing 2 wt% glass addition sintered at 1050℃for 4 h possess excellent microwave dielectric properties:dielectric constant(ε_(r))=44.3,quality factor multiplied by resonant frequency(Q×f)=23,820 GHz(f=6.2 GHz),and the temperature coefficient of resonant frequency(τ_(f))=123.2 ppm/℃.
文摘Electromagnetic absorbing materials may convert electromagnetic energy into heat energy and dissipate it.However,in a high-power electromagnetic radiation environment,the temperature of the absorbing material rises significantly and even burns.It becomes critical to ensure electromagnetic absorption performance while minimizing temperature rise.Here,we systematically study the coupling mechanism between the electromagnetic field and the temperature field when the absorbing material is irradiated by electromagnetic waves.We find out the influence of the constitutive parameters of the absorbing materials(including uniform and non-uniform)on the temperature distribution.Finally,through a smart design,we achieve better absorption and lower temperature simultaneously.The accuracy of the model is affirmed as simulation results aligned with theoretical analysis.This work provides a new avenue to control the temperature distribution of absorbing materials.
基金supported by the National Natural Science Foundation of China(Nos.51972045 and 5197021414)the Fundamental Research Funds for the Chinese Central Universities,China(No.ZYGX2019J025)+2 种基金Sichuan Science and Technology Program(Nos.2020JDRC0015 and 2020JDRC0045)the Natural Science Foundation of Sichuan(No.2022NSFSC0347)Sichuan Science and Technology Innovation Talent Project(No.2021JDRC0021).
文摘Environmentally-friendly magnetic metallic absorbers with high-performing antioxidant property,thermal stability,and anticorrosion capability have attracted great attention in real-world applications.A surface modification technology of magnetic metallic absorbers with dense and inert materials has been an effective strategy to solve the aforesaid problem.Herein,fluorinefree core–shell carbonyl iron-organic silicon absorbers(CI@SiO_(2)/1,1,1,3,3,3-hexamethyl disilazane(HMDS))were fabricated via a facile one-pot synthesis using tetraethyl orthosilicate(TEOS)and HMDS as the precursor of protective layer(SiO_(2)/HMDS),and CI@SiO_(2)/HMDS hybrid reveals its long-term corrosion resistance and excellent microwave absorption performance with a minimum reflection loss value of−44.3 dB and an effective absorption bandwidth of 5.3 GHz at a thin thickness of 2.0 mm after immersion in 5.0 wt.%NaCl acidic solutions for 2,160 h.Meanwhile,CI@SiO_(2)/HMDS hybrid can still achieve the maximum radar cross-sectional(RCS)reduction values about 16.5 dB·m^(2) at the detectionθof 0°.The exceptional microwave absorption performance and structural stability are largely due to the extraordinary wave-transparent property and shielding ability against corrosive medium of SiO_(2)/HMDS hydrophobic protective layer with a contact angle of 132.5°.The research paves the way for the large-scale and batch production of high-performance magnetic metallic absorbers and increases their survivability and reliability in the harsh environments.
基金supported by the National Natural Science Foundation of China(Grant No.51872037).
文摘The explosive process of 5G communication evokes the urgent demand of miniaturized and integrated dielectric ceramics filter It is a pressing need to advance the development of dielectric ceramics utilization of emerging technology to design new materials and understand the polarization mechanism.This review provides the summary of the study of microwave dielectric ceramics(MWDCs)sintered higher than 1000℃ from 2010 up to now,with the purpose of taking a broad and historical view of these ceramics and illustrating research directions.To date,researchers endeavor to explain the structure-property relationship of ceramics with multitude of approaches and design a new formula or strategy to obtain excellent microwave dielectric properties.There are variety of factors that impact the permittivity,dielectric loss,and temperature stability of dielectric materials,covering intrinsic and extrinsic factors.Many of these factors are often intertwined,which can complicate new dielectric material discovery and the mechanism investigation.Because of the various ceramics systems,pseudo phase diagram was used to classify the dielectric materials based on the composition.In this review,the ceramics were firstly divided into ternary systems,and then brief description of the experimental probes and complementary theoretical methods that have been used to discern the intrinsic polarization mechanisms and the origin of intrinsic loss was mentioned.Finally,some perspectives on the future outlook for high-temperature MWDCs were offered based on the synthesis method,characterization techniques,and significant theory developments.
基金the financial support from the National Natural Science Foundation of China (51602040 and 51872039)the Science and Technology Program of Sichuan (M112018JY0025)the Scientific Research Foundation for New Teachers of UESTC (A03013023601007)
基金supported by the National Natural Science Foundation of China(51602040,51872039,51525202 and 51902098)the Science and Technology Program of Sichuan(M112018JY0025)+1 种基金Scientific Research Foundation for New Teachers of UESTC(A03013023601007)the Ministry of Science and Technology of China(MOST,2016YFA0300802)。
基金financial supports from the National Natural Science Foundation of China(No.51872037).
文摘This article presents low-firing,low-loss and temperature stable ZnO-TiO_(2)-Nb_(2)O_(5) microwave dielectric composite ceramics with the assistance of lithium borosilicate(LBS)and zinc borosilicate(ZBS)glass frits.There is a liquid phase(eutectic mixture)generated by LBS(ZBS)glass,and solid particles could be wetted and dissolved.Therefore,the migrations and rearrangements of particles could be performed.Besides,compared with ceramics undoped with glass frits,lower activation energies(E_(a))of ceramics doped with LBS and ZBS glass suggest that the low-temperature sintering behavior is easier to carry out.The results indicated that LBS and ZBS glass both are effective sintering aids to accelerate the sintering process and improve the microwave dielectric properties of composite ceramics by controlling the phase compositions under low temperature.Combination great properties of ZnO-TiO_(2)-Nb_(2)O_(5) ceramics were obtained when sintered at 900℃ for 4 h:ε_(r)=36.7,Q×f=20,000 GHz,τ_(f)=7 ppm/℃.
基金National Natural Science Foundation of China(NSFC)(51602040)Scientific Research Foundation for New Teachers of University of Electronic Science and Technology of China(UESTC)(A03013023601007,ZYGX2015KYQD057)
文摘Although plasmonic nanostructure has attracted widespread research interest in recent years, it is still a major challenge to realize large-scale active plasmonic nanostructure operation in the visible optical frequency. Herein,we demonstrate a heterostructure geometry comprising a centimeter-scale Au nanoparticle monolayer and VO_2 films, in which the plasmonic peak is inversely tuned between 685 nm and 618 nm by a heating process since the refractive index will change when VO_2 films undergo the transition between the insulating phase and the metallic phase. Simultaneously, the phase transition of VO_2 films can be improved by plasmonic arrays due to plasmonic enhanced light absorption and the photothermal effect. The phase transition temperature for Au∕VO_2 films is lower than that for bare VO_2 films and can decrease to room temperature under the laser irradiation. For lightinduced phase transition of VO_2 films, the laser power of Au∕VO_2 film phase transition is ~28.6% lower than that of bare VO_2 films. Our work raises the feasibility to use active plasmonic arrays in the visible region.