|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures显示文摘Te mechanism of negative permittivity/permeability is still unclear in the random metamaterials,where the precise control of microstructure and electromagnetic properties is also a challenge due to its random characteristic.Here silver was introduced into porous SiO_(2) microsphere matrix by a self-assemble and template method to construct the random metamaterials.Te distribution of silver was restricted among the interstices of SiO_(2) microspheres,which lead to the precise regulation of electrical percolation(from hoping to Drude-type conductivity)with increasing silver content.Negative permittivity came from the plasma-like behavior of silver network,and its value and frequency dispersion were further adjusted by Lorentz-type dielectric response.During this process,the frequency of epsilon-near-zero(ENZ)could be adjusted accordingly.Negative permeability was well explained by the magnetic response of eddy current in silver micronetwork.Te calculation results indicated that negative permeability has a linear relation with ω^(0.5),showing a relaxation-type spectrum,diferent from the“magnetic plasma”of periodic metamaterials.Electromagnetic simulations demonstrated that negative permittivity materials and ENZ materials,with the advantage of enhanced absorption(40dB)and intelligent frequency selection even in a thin thickness(0.1 mm),could have potentials for electromagnetic attenuation and shielding.Tis work provides a clear physical image for the theoretical explanation of negative permittivity and negative permeability in random metamaterials,as well as a novel strategy to precisely control the microstructure of random metamaterials. | Peitao Xie Zidong Zhang Zhongyang Wang Kai Sun Runhua Fan | 2019 | Research2019，，1： | 6 |
| 2 | Doped ceramics of indium oxides for negative permittivity materials in MHz-kHz frequency regions显示文摘Negative permittivity has been widely studied in various metamaterials and percolating composites, of which the anomalous dielectric behavior was attributed to critical structural properties of building blocks.Herein, mono-phase ceramics of indium tin oxides(ITO) were sintered for epsilon-negative materials in MHz-k Hz frequency regions. Electrical conductivity and complex permittivity were analyzed with DrudeLorentz oscillator model. Carriers’ characters were measured based on Hall effect and the magnitude and frequency dispersion of negative permittivity were mainly determined by carrier concentration.Temperature-dependent dielectric properties further proved the epsilon-negative behaviors were closely associated with free carriers’ collective responses. It’s found that negative permittivity of ITO ceramics was mainly caused by plasma oscillations of free carriers, while the dielectric loss was mainly attributed to conduction loss. Negative permittivity realized here was related to materials intrinsic nature and this work preliminarily determined the mechanism of negative permittivity in doped ceramics from the perspective of carriers. | Guohua Fan Zhongyang Wang Kai Sun Yao Liu Runhua Fan | 2021 | Journal of Materials Science & Technology2021，，2： | 3 |
| 3 | Epsilon-negative BaTiO_(3)/Cu composites with high thermal conductivity and yet low electrical conductivity显示文摘Epsilon-negative materials with high thermal conductivity and low electrical conductivity are of great importance for high power microwave devices.In this work,BaTiO_(3)/Cu composites,as a class of epsilonnegative materials,are rationally designed to achieve a high thermal conductivity yet maintaining the electrical insulative character.Negative permittivity behavior induced by dielectric resonance and plasma oscillation is observed in these BaTiO_(3)/Cu composites,which can be explained by the Lorentz and Drude model respectively.An outstanding absorption ability is achieved near the zero-cross point of the permittivity.Benefiting from the positive temperature coefficient of resistance and the weak temperature dependence of thermal conductivity in BaTiO_(3)/Cu composites,sample containing 22.3 vol% of Cu content exhibits a thermal conductivity of up to 17.7 W/(m·k)and an electrical conductivity down to 0.0022(Ω cm)^(-1) at 150℃.Therefore,BaTiO_(3)/Cu composite is a promising candidate for applications in electromagnetic attenuation and thermal management. | Zhongyang Wang Kai Sun Peitao Xie Yao Liu Qilin Gu Runhua Fan John Wang | 2020 | Journal of Materiomics2020，6，1： | 3 |
| 4 | Defect-induced insulator-metal transition and negative permittivity in La_(1-x)Ba_(x)CoO_(3)perovskite structure显示文摘The development of negative permittivity materials in multifunctional applications requests expansion of their operating frequency and improvement of stability of negative permittivity.Low electron density is beneficial to reduce plasma frequency so that negative permittivity is achieved in kHz region.Negative permittivity achieved by percolating composites is restricted in practicality due to its instability nature at high temperatures.To achieve temperature-stable negative permittivity in kHz region,monophase La_(1-x)Ba_(x)CoO_(3)ceramics were prepared,and the transition from dielectric to metal was elaborated in the perspective of electrical conductivity and negative permittivity.The plasma-like negative permittivity is attained in kHz region,which is interpreted by the collective oscillation of low electron density.The temperature-stable negative permittivity is based on the fact that the plasmonic state will not be undermined at high temperatures.In addition,zero-crossing behavior of real permittivity is observed in La_(0.9)Ba_(0.1)CoO_(3)sample,which provides a promising alternative to designing epsilon-near-zero materials.This work makes the La_(1-x)Ba_(x)CoO_(3)system a source material for achieving effective negative permittivity. | Zaixin Wei Zhongyang Wang Ciqun Xu Guohua Fan Xiaoting Song Yao Liu Runhua Fan | 2022 | Journal of Materials Science & Technology2022，，17： | 2 |
| 5 | 显示文摘 | Fan Runhua Chen Yun Zhang Jingde | 2004 | Journal of Functional Materials2004，35，4： | 1 |
| 6 | Kinetics of thermite reaction in A1-Fe2O3 system显示文摘 | Fan Runhua Lu Hongliang Sun Kangning | 2006 | Thermochimica Acta2006，440，： | 1 |
| 7 | Ki-netics of thermite reaction in Al-Fe203 system 显示文摘 | Fan Runhua Lii Hongliang Sun Kangning | 2005 | Thermochimica Acta2005，440，2： | 1 |
| 8 | Effects of exogenous nitric oxide on growth, active oxygen species metabolism, and photosynthetic characteristics in cucumber seedlings under NaCl stress显示文摘 | Huaifu Fan Shirong Guo Yansheng Jiao Runhua Zhang Juan Li | 2007 | Frontiers of Agriculture in China2007，，3： | 1 |
| 9 | Kinetics of thermite reaction in A1-Fe203 system 显示文摘 | Fan Runhua Lfl Hongliang Sun Kangning | 2006 | Thermochimica Acta2006，440，： | 1 |
| 10 | Preparation and mechanical properties of Fe3Al/Al2O3 nano-micro-composite 显示文摘 | YIN Yansheng GONG Hongyu FAN Runhua | 2003 | Trans Nonferrous Met Soc China2003，13，6： | 1 |
| 11 | 显示文摘 | Fan Runhua Chen Yun Zhang Jingde | 2004 | Journal of Functional Materials2004，35，4： | 1 |
| 12 | 显示文摘 | FAN Huaifu GUO Shirong JIAO Yansheng ZHANG Runhua LI Juan College of Horticulture Nanjing Agricultural University Nanjing 210095 China.? Effects of exogenous nitric oxide on growth active oxygen species metabolism and photosynthetic characte | 2007 | Frontiers of Agriculture in China2007，，03： | 1 |
| 13 | Moisture-proof and Enhanced Effect of Inorganic Coating on Porous Si_3N_4 Ceramic显示文摘Inorganic coating was fabricated on the surface of the porous Si3N4 ceramic by polymer derived(PD) and spraying technology, via using vinyl-polysilazane(PSN-1) as a preceramic polymer and Si3N4 and lithium aluminosilicate(LAS) powders as fillers. The phase and microstructure of the coatings were analyzed by X-ray diffraction(XRD) analysis and scanning electron microscopy(SEM), respectively. The effect of the coatings on mechanical property and humidity resistance of the porous Si3N4 ceramic was investigated. The experimental results showed that we successfully fabricated the uniform and dense coating which preferably combined with the substrate upon the addition of fillers. The bending strength of the porous Si3N4 ceramic sprayed the coating increased by more than 18%, and the surface hardness increased by 1.7 times. The apparent porosity of the materials reduced by an average of 97.7%, and water absorption was below 0.5%. Therefore, the prepared coating with preferable density had an obviously moisture-proof and enhanced effect on the porous Si3N4 ceramic. | 程传兵 FAN Runhua WANG Chonghai WANG Hongsheng ZHOU Changling 刘福田 | 2015 | Journal of Wuhan University of Technology(Materials Science)2015，30，2： | 1 |
| 14 | Negative permittivity derived from inductive characteristic in the percolating Cu/EP metacomposites显示文摘Recently,increasing attention has been concentrated on negative permittivity with the development of the emerging metamaterials composed of periodic array structures.However,taking facile preparation into consideration,it is important to achieve negative permittivity behavior based on materials'intrinsic properties rather than their artificially periodic structures.In this paper,we proposed to fabricate the percolating composites with copper dispersed in epoxy(EP)resin by a polymerization method to realize the negative permittivity behavior.When Cu content in the composites reached to 80 wt%,the conductivity abruptly went up by three orders of magnitudes,suggesting a percolation behavior.Below the percolation threshold,the conductivity spectra conform to Jonscher's power law;when the Cu/EP composites reached to percolating state,the conductivity gradually reduced in high frequency region due to the skin effect.It is indicated that the conductive mechanism changed from hopping conduction to electron conduction.In addition,the permittivity did not increase monotonously with the increase of Cu content in the vicinity of percolation threshold,due to the presence of leakage current.Meanwhile,the negative permittivity conforming to Drude model was observed above the percolation threshold.Further investigation revealed that there was a constitutive relationship between the permittivity and the reactance.When conductive fillers are slightly above the percolation threshold,the inductive characteristic derived from conductive percolating network leads to the negative permittivity.Such epsilon-negative materials can potentially be applied in novel electrical devices,such as high-power microwave filters,stacked capacitors,negative capacitance field effect transistors and coil-free resonators.In addition,the design strategy based on percolating composites provides an approach to epsilon-negative materials. | Kai Sun Jiahao Xin Yaping Li Zhongyang Wang Qing Hou Xiaofeng Li Xinfeng Wu Runhua Fan Kwang Leong Choy | 2019 | Journal of Materials Science & Technology2019，35，11： | 0 |
| 15 | Flexible and biocompatible poly(vinyl alcohol)/multi-walled carbon nanotubes hydrogels with epsilon-near-zero properties显示文摘Epsilon-near-zero(ENZ)material has been a research hotspot in recent years due to unique physical properties such as inverse Doppler effect and negative refractive index,showing great potentials in the fields of flexible electronics,wearable devices,sensors,etc.The ENZ materials are mostly reported at visible,infrared and terahertz wavelengths,while the report about ENZ materials at radio frequency is rare.In this work,flexible and biocompatible poly(vinyl alcohol)/multi-walled carbon nanotubes(PVA/MWCNTs)hydrogels,which were successfully fabricated by an environmentally friendly method,were used as ENZ materials at radio frequency for the first time.Cytotoxicity experiments proved that the experimental process and products are green,environmentally friendly and biocompatible.The microstructure,crystalline structure,chemical composition and dielectric properties were investigated.Two different water states,which were free water molecules and bound water molecules,coexisted in these PVA/MWCNTs hydrogels and accounted for about 37.5 wt%and 15.9 wt%respectively by analyzing the thermogravimetric analysis curves.When the MWCNTs content reached 12 wt%and 15 wt%,the continuous conductive MWCNTs network was formed in the hydrogel,and ENZ phenomenon was observed at about 760 k Hz and 580 k Hz respectively,which was attributed to the interband transition.Considering the flexibility and non-toxicity of PVA/MWCNTs hydrogels,the ENZ properties of this structure at the radio frequency can be well used in wearable invisibility cloak,flexible electronics,skin sensors and other wearable devices. | Jiahong Tian Runhua Fan Zheng Zhang Yang Li Haikun Wu Pengtao Yang Peitao Xie Wenxin Duan Chun-Sing Lee | 2022 | Journal of Materials Science & Technology2022，，36： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员