MATERIALS LETTERS
·
2022
·
IF 3.574
Jinke Song,Guangyue Shi,Xiaoting Song,Zidong Zhang,Yao Liu,Runhua Fan
Composites with negative permittivity behavior have brought about widespread attention for their broad application prospects in electromagnetic field or being used for novel capacitance. In this work, multiwall carbon nanotubes/polyvinylidene fluoride (MWCNTs/PVDF) composites with gradually increasing MWCNT filling content were prepared by hot-pressing in order to acquire negative permittivity. The microstructure, ac conductivity, and real permittivity of the samples were elaborated. As MWCNTs content increases, the percolation phenomenon occurs accompanied by the conversion of conductive mechanism from hopping conduction to free electron conduction. It’s found that negative permittivity property was obtained at a lower filler content and can be regulated by controlling MWCNTs content, which is related to the plasma oscillation state of free electrons in MWCNTs.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2018
·Vol. 29
·期 18
·15994-16003
·
IF 2.324
Xu Ciqun,Qu Yunpeng,Fan Guohua,Xie Peitao,Ren Huan,Chen Jiaqi,Liu Yao,Wu Yulin,Fan Runhua
Metacomposites have been induced widespread concern in the realization of negative permittivity. In this paper, composites with titanium nitride (TiN) particles homogeneously dispersed in polyethylene terephthalate (PET) resin were prepared by high energy ball-milling and adhesive hot-pressing method. The influences of TiN networks in composites on the electric and dielectric properties were investigated in detail. With the formation of conductive TiN networks, the conductance mechanism changed from hopping conduction to metal-like conduction. The tunable and weakly negative permittivity in the radio frequency range was obtained in TiN/PET composites by adjusting the frequency range and volume fraction ( v ) of TiN in composites. Negative permittivity behavior raises from the low-frequency plasma oscillation of free electrons in TiN networks, which could be analyzed by the Drude model. The impedance of TiN/PET composites were investigated by the equivalent circuit analysis, demonstrating the capacitive or inductive of the composites. This paper shows an effective way toward the tunable and weakly negative permittivity, which will promote practical applications of metacomposites in electromagnetic shielding and impedance matching fields.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES SCIENCE AND TECHNOLOGY
·
2021
·
IF 8.528
Yunpeng Qu,Zhongyang Wang,Peitao Xie,Zongxiang Wang,Runhua Fan
Metacomposites have drawn considerable attention due to their enticing prospect in electronic and dielectric devices, which meanwhile unfortunately suffered from extremely high negative permittivity ( ε' < 0). Herein, we put forward a strategy to suppress the plasma oscillation in metacomposites and thereby constrain the value of negative permittivity by introducing the semiconductive polyaniline to construct polyaniline/nickel (PANI/Ni) metacomposites. Weakly negative permittivity was obtained at a magnitude of 10 2 over the whole test frequency band, which is remarkably lower by at least three orders of magnitude than that of most metacomposites. The ε′ -negative value was resultantly fine-tuned by about 10 2 with equally adjusting Ni content. Lorentz and Drude models were employed to describe ε′ -negative spectra, indicating that both dielectric resonance and plasma oscillation contributed to negative permittivity. Negative susceptibility of ε′ -negative materials was mainly ascribed to high-frequency diamagnetic response within Ni networks. The well-designed PANI/Ni metacomposites with weakly and fine-tuning negative permittivity can greatly benefit the practical applications on electromagnetic (EM) shielding, microwave absorption and novel EM sensors.
研究领域:
材料科学
·
电子与电磁学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materiomics
·
2019
·
IF 0
Peng Wang,Zhongbin Pan,Mingkun Wang,Shuangwu Huang,Jinjun Liu,Jiwei Zhai
Percolating composites with negative permittivity can be promising candidates for metamaterials. Herein, novel all-organic composite films containing of random coil polypyrrole (PPy) and poly(vinylidene fluoride) (PVDF) are fabricated via a solution casting method. The random coil PPy is prepared by oxidative template assembly approach for the first time. The experimental result indicates that the negative permittivity is easily adjusted through controlling the random coil PPy contents. Especially, the random coil PPy contents exceeded 7 wt% the negative permittivity appear attributed to the formation of 3D interconnected PPy network. This facile approach not only opens a new way to preparing negative permittivity of all-organic composite films, but also points out a route to facilitate the practical applications of metamaterials.
研究领域:
材料科学
·
有机电子学
✓ 已验证
DOI
Journal of Materials Chemistry C
·
2020
·Vol. 8
·期 33
·11610-11617
·
IF 7.059
Guohua Fan,Zhongyang Wang,Kai Sun,Yao Liu,Runhua Fan
Materials with negative permittivity have recently become a research hotspot due to their potential applications in electromagnetic shielding, novel capacitance, inductor design, etc. Negative permittivity realized in metamaterials and multicomponent composites are determined by the critical building blocks within them. Herein, from the perspective of intrinsic properties of mono-phase materials, Sb-doped SnO2 (ATO) was synthesized by a hydrothermal method and sintered into mono-phase ceramics to be negative permittivity materials. The influences of Sb-doping on the electric and dielectric properties of the ceramics were studied. It was found that the electron concentration was increased as Sb-doping amount increases in a certain range, leading to the decrease in resistivity. Negative permittivity was observed owing to the plasma oscillations of free carriers derived from donor Sb-dopants. Moreover, the evident dielectric loss accompanied with plasma-like negative permittivity was completely caused by loss of conduction. In addition, reactance analysis revealed that epsilon-negative ceramics were electrically inductive. This work explored the unusual dielectric properties of ATO ceramics and elucidated the mechanism and physical significance of negative permittivity in doped mono-phase ceramics.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 28
·14575-14582
·
IF 8.867
Zhicheng Shi,Jing Wang,Fan Mao,Chaoqiang Yang,Chao Zhang,Runhua Fan
High-k polymer composites are promising candidates for energy-storage capacitors and many other electronic devices. However, balancing the permittivity, loss and breakdown strength remains a challenge for us. Herein, theoretical calculations and experimental studies were simultaneously carried out to develop an original design of sandwich-structured composites consisting of alternating negative-k and positive-k layers toward high performance dielectric applications. It is experimentally proved that the trilayered composites are capable of balancing the two contrasting parameters of permittivity and loss. The introduction of negative-k layers into trilayered composites leads to a higher dielectric constant (ε′ ≈ 90@10 kHz) and low retained loss (tan δ ≈ 0.025@10 kHz) compared with those of the pristine PVDF (ε′ ≈ 10@10 kHz, tan δ ≈ 0.020@10 kHz). Moreover, the trilayered composites possess an obviously improved energy-storage capacity which is nearly 3 times higher than those of traditional trilayered composites without negative-k layers. Although the permittivity boost effect is still far below the theoretically predicted results and the mechanisms need to be further clarified, these results undoubtedly validated the feasibility of our design, and multilayer high-k composites with fascinating dielectric performances are expected to emerge in the near future via tailoring the properties of single layers and stacking sequences.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
ACTA MATERIALIA
·
2019
·
IF 7.293
Zhongyang Wang,Kai Sun,Peitao Xie,Qing Hou,Yao Liu,Qilin Gu,Runhua Fan
As an important supplement to the metamaterials , negative permittivity in 'natural' materials has attracted increasing attention, while some fundamental regulation mechanisms and common theoretical principles have not yet been systematically explored. In this paper, the permittivity transition is investigated along with insulator-conductor conversion in BaTiO 3 /Ni composite. When the Ni content in BaTiO 3 /Ni composites is lower than and higher than the percolation threshold, Lorentz-like and Drude-type negative permittivity behaviors is obtained, respectively. In addition, the fundamental principles of negative permittivity are discussed, especially the validity of the Kramers–Kronig relations and the relationship between the negative permittivity and the reactance characters. Further, a universal regulatory mechanism of the Drude-type negative permittivity profile is qualitatively analyzed. Negative permittivity and negative permeability are achieved simultaneously in BaTiO 3 /Ni composites with 35.56 vol% of Ni loading, which show potential application in electromagnetic wave absorption and shielding.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Zhongyang Wang,Peitao Xie,Guohua Fan,Zidong Zhang,Yao Liu,Qilin Gu,Runhua Fan
Epsilon-negative behavior in metamaterials has attracted increasing attention recently. In this work, excessively percolating BaTiO 3 /Ag composites were synthesized by an in-situ preparation method to achieve negative permittivity. The epsilon-negative behavior is explained by low-frequency plasma oscillation of free electrons, which can be well fitted by the Drude model. Moreover, the negative permittivity of composites can be tuned by adjusting the content of randomly distributed Ag particles. The ac conductivity of excessively percolating BaTiO 3 /Ag composites shows a typical metal-like behavior. Furthermore, the investigation of reactance reveals that the inductive character derived from the conductive network is the main contributor to negative permittivity, as confirmed by the equivalent circuit analysis. This work provides a theoretical recipe for designing negative permittivity, supplements the family of metamaterials, and would further facilitate the practical applications of epsilon-negative materials in electromagnetic devices.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
DIAMOND AND RELATED MATERIALS
·
2023
·
IF 4.1
Benli Du,Zihao Guo,Zhihao Sun,Yu Qiu,Peng Wang,Han Ding,Shaoyao Tian,Lei Qian
Negative dielectric materials show bright application prospects in the electromagnetic protection, energy storage and radio transmission fields. However, high negative permittivity and expensive manufacturing costs limit their applications in above fields. Here, phenolic resin composites containing short carbon fibers (SCF) with different length-diameter ratios were prepared by mechanical mixing and dry pressing. The effects of length-diameter ratio and mass fraction of SCF on conductivity, permittivity and impedance were investigated. The AC conduction mechanism changed from jump conduction to metal-like conduction due to the increased carrier concentration resulting from improved connectivity of the 3D conductive network. In addition, a weak negative permittivity was obtained in SCF 429 -10/PF composite. At SCF of 20 wt%, when the length-diameter ratio increased from 114 to 429, the negative permittivity mechanism changed from Lorentz & Drude to Drude model, indicating that the plasma oscillation of delocalized electrons was the main cause of negative permittivity. The relationship between reactance and permittivity were discussed by impedance and equivalent circuit analysis . This work provided a new strategy for obtaining weak negative permittivity, which exhibited potential applications in the fields of electromagnetic protection, high dielectric capacitors, and perfect absorption.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
ECS Journal of Solid State Science and Technology
·
2020
·Vol. 9
·期 5
·053003
·
IF 2.142
Hanying Wang,Chunyuan Deng,Kai Sun,Yunpeng Qu,Runhua Fan
In this paper, FeCrNi/CaCu3Ti4O12 metacomposites with different FeCrNi content were fabricated by low-temperature presureless sintering process. With increasing FeCrNi content above percolation threshold, the conduction mechanism changed from hopping conduction to metal-like conduction. Meanwhile, epsilon-negative property was obtained at 70 wt%–90 wt% content of FeCrNi, ascribing to the low frequency plasmonic state from three-dimensional conductive FeCrNi networks. The correlation between epsilon-negative property and inductive character was clarified by reactance spectrum. This work benefited the exploration of metal/ceramic metacomposites which could facilitate their promising applications in invisibility, high-k capacitors, novel antennae and sensors.
研究领域:
材料科学
·
电磁学
·
纳米技术
✓ 已验证
DOI
高影响因子
SCRIPTA MATERIALIA
·
2020
·
IF 5.079
Guohua Fan,Zhongyang Wang,Huan Ren,Yao Liu,Runhua Fan
In this work, dielectric behaviors of dielectric resonance, relaxation, and plasma-like negative permittivity are observed in percolative copper/rutile cermets . Transition for permittivity changing from positive to negative is associated with composition and determined by percolation . The resonance and relaxation responses are related to isolated metallic particles or clusters. Negative permittivity is induced by the plasmonic state of electrons within percolating pathways and dielectric loss of epsilon-negative composites is dominated by conduction loss. Besides, the percolative cermets change from electrical capacitive to inductive with the permittivity transition. Epsilon-negative cermets are expected to be used for electromagnetic shielding and coil-less electrical inductors.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
Functional Materials Letters
·
2020
·
IF 2
Yao Liu,Ciqun Xu,Huan Ren,Zaixin Wei,Zidong Zhang
Meta-composites with negative permittivity are promising candidates for future electronics such as microwave absorbers, novel capacitors, etc. In this work, we proposed to develop the Fe/BaTiO 3 meta-composites with tuneable negative permittivity. Fe content influenced the conductivity of composites and even led to the change of the conductive mechanism. The tuneable permittivity behavior was achieved by controlling the Fe fraction, and the plasma oscillation theory was employed to explain the negative permittivity behavior. Meanwhile, a frequency-switched negative permittivity was observed in this composite, which could be used to extend applications of meta-composites.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）