Materials Today Physics
·
2021
·
IF 9.298
Feichong Yao,Wenhao Xie,Ming Yang,Hang Zhang,Hongbo Gu,Ai Du,Nithesh Naik,David P. Young,Jing Lin,Zhanhu Guo
With the purpose of ameliorating the electrical property, permittivity and magnetoresistance of polyaniline (PANI) nanofibers , three types of phenylenediamine (PDA), including o -PDA, m -PDA, and p -PDA, and different contents of PDA have been incorporated into the PANI polymer backbone by the interfacial copolymerization of aniline with PDA. The results demonstrate that different types and contents of PDAs could disclose the distinct effects on the chemical structures , crystalline structures, and morphologies for copolymers of aniline with PDA affirmed by Fourier transform infrared (FTIR) spectroscopy, solid-state 13 C nuclear magnetic resonance ( 13 C NMR), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The molecular weight of all copolymers is reduced by several orders of magnitude relative to pure PANI nanofibers confirmed by gel permeation chromatography (GPC). The resistivity variations for the copolymers of aniline with different types of PDAs are well explained from the point view of their molecular structures based on the first-principle simulations (i.e. intrachain electrical conductivity) and degree of crystallinity gained from XRD (i.e. interchain electrical conductivity). A tunable room-temperature magnetoresistance (MR) and a controllable negative permittivity are discovered in the copolymers of aniline with different types and contents of PDAs. This work provides a new insight for the manipulation of electrical transport for PANI nanofibers and helps seek the new applications of conductive polymer .
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Xiao Sun,Chuanbing Cheng,Jianxing Shen,Yang Liu,Tailin Wang,Qian Ma,Runhua Fan
In this work, amorphous carbon/alumina (C/Al 2 O 3 ) metacomposites with tunable negative permittivity were synthesized by a facile impregnation method. We analyzed the influence of carbon content and the carbonization temperature on the microstructure and electrical properties of the metacomposites. It was found that the conductive carbon networks were formed in the composites with the higher carbon contents and carbonization temperatures, which lead to the appearance of a metal-like conduction and negative permittivity behavior. Low-frequency plasmonic state provided by plenty of free electrons in the carbon networks resulted in the negative permittivity, and its numerical values could be effectively adjusted by controlling the carbon content and carbonization temperature, which could be well explained by Drude model. This work provides a feasible way to prepare metacomposites with tunable negative permittivity, which will expand their potential applications in shielding, absorbing and novel capacitor 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
POLYMER COMPOSITES
·
2020
·Vol. 41
·期 5
·1820-1829
·
IF 2.265
Yuliang Zhang,Kuan Yin,Kai Sun,Shengjia Cao,Fujun Tao,Binbin Wang,Li Li,Xueting Chang,Liangjun Huang,Runhua Fan
In recent years, random metacomposites with tunable negative permittivity have aroused widespread attention because of their distinctive properties and broad potential prospects. It is indicated that an enormously negative permittivity with a large value is not conducive to performance optimizing and impedance matching. In this article, the 2D Mxene Ti 3 C 2 T x was selected as the conductive phase instead of metal and carbon materials to fabricate Ti 3 C 2 T x /poly(vinylidene fluoride) metacomposites. The results of dielectric properties indicated that the conductive Ti 3 C 2 T x networks were formed by Ti 3 C 2 T x contacting with each other near the percolation threshold (ƒ c ). The as-obtained metacomposites containing 75 wt% Ti 3 C 2 T x generated percolating phenomenon. Additionally, when the fraction of Ti 3 C 2 T x was below ƒ c , the frequency dispersion behaviors of conductivity were in accordance with the Jonscher's power law, which proved that conducting mechanism was dependent on hopping conduction. While above ƒ c , the conductivity conformed to the Drude model and Lorentz model, which demonstrated a conductive behavior. Furthermore, the real part of permittivity transformed to negative value at 75 wt%, which can be explained as the existence of the low-frequency plasma oscillation and electric-dipole-induced resonance. The dielectric loss of the metacomposite was also analyzed by the imaginary permittivity spectra. Small negative permittivity values in the range of −550 to −400 were observed, owing to the low free carrier concentration in composites. The appearance of weakly negative permittivity opened up a new direction in negative dielectric materials by 2D layered Ti 3 C 2 T x nanomaterials.
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
Advanced Composites and Hybrid Materials
·
2018
·Vol. 1
·期 3
·548-557
·
IF 0
Mao Fan,Shi Zhicheng,Wang Jing,Zhang Chao,Yang Chaoqiang,Huang Minghua
The search for high-performance dielectric materials has long been driven by the urgent needs for various modern electronics. However, enhanced permittivity is always accompanied by elevated loss, which seriously hinders the development and applications of dielectric materials. Herein, negative- k layers were introduced into layer-structured films, forming a new class of multilayer composites consisting of alternately stacked positive- k and negative- k layers. Compared with traditional multilayer composites without negative- k layers, the layered composites containing extra positive- k /negative- k interfaces exhibit superior ability in balancing the contradict parameters: permittivity and loss, yielding substantially enhanced permittivity without sacrificing the low loss. It is indicated that the permittivity was enhanced by the charge accumulations and reinforced polarizations on the interfaces between positive- k and negative- k layers. Meanwhile, the loss induced by the leakage current was suppressed by the blocked transport of carriers between adjacent layers. The trilayered 60-3.5-60 composite exhibits an enhanced dielectric constant ( ε ′ ≈ 33 @10 kHz) and retained low loss (tanδ ≈ 0.12 @10 kHz) compared with the single-layer BT/PVA composite containing 60 wt% BT fillers ( ε ′ ≈ 9.5 @10 kHz, tanδ ≈ 0.075 @10 kHz). This research offers an effective way to design and fabricate novel high-performance dielectric materials.
Improved dielectric permittivity and retained low loss were obtained in layer-structured films via adjusting interfaces.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
Advanced Composites and Hybrid Materials
·
2023
·Vol. 6
·期 2
·1-12
·
IF 20.1
Zeng Junling,Xie Wenhao,Zhou Heng,Zhao Tong,Xu Ben Bin,Jiang Qinglong,Algadi Hassan,Zhou Zhenyu,Gu Hongbo
Herein, a nitrogen-doped graphite-like carbon material derived from hybrid phthalonitrile (PN) resin with controllable carbon microstructures including crystalline structures, hybridized carbon configurations, degree of disorder, and nitrogen species such as pyridinic N, pyrrolic N, and graphitic N has been manufactured by high-temperature annealing method. By simply altering these carbon microstructures through annealing temperature, the lowest resistivity of 1.76 Ω·cm at 290 K, the negative MR value of − 6.10% at a magnetic field of 9 T and negative permittivity over − 10 5 at low frequency are achieved in the semiconducting nitrogen-doped graphite-like carbon material. The results confirm the decreasing degree of disorder attained from Raman spectroscopy, the increasing ratio of sp 2 and sp 3 hybridized carbon, i.e., C( sp 2 )/C( sp 3 ), from X-ray photoelectron spectroscopy (XPS), and the rise of charge carrier mobility with increasing the magnetic field from Hall-effect measurement is responsible for the negative MR effect in this nitrogen-doped graphite-like carbon material. The negative permittivity is attributed to the plasma oscillation with delocalized charge carriers by the Drude model and the greatly increasing graphitic N in the carbon microstructures. This work opens a new insight for the applications of carbonized PN resins in the electronic device field.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2025
·
IF 6.9
Jingyu Bi,Benli Du,Zihao Guo,Zhihao Sun,Guangshen Li,Jianshu Wang,Ying Sha,Lei Qian
High negative permittivity of most metacomposites has significant limitations for various applications, so design of novel metacomposites with weakly negative dielectric constants still is a critical challenge. In this work, activated carbon felt-polyaniline (ACF-PANI) metacomposites with high compressibility have been prepared through in-situ polymerization of PANI on ACF, and the effect of PANI polymerization on the dielectric properties of the ACF-PANI metacomposites has been investigated. Adjusting the in-situ polymerization time can precisely control the loading of PANI on ACF, thereby achieving controllable negative permittivity. By optimizing the polymerization time to 240 min, we have successfully achieved a weak negative permittivity of approximately −30 from 50 kHz to 1 MHz, and the dispersion of ACF-PANI 240 is only 26. This is attributed to the unique protonic conduction of PANI, which dilutes the carrier concentration in the metacomposite material and enhances the carrier mass, thereby suppressing plasma the oscillations. Moreover, the negative permittivity of the compressible ACF-PANI metacomposites could be dynamically tuned based on its deformation, and the change in negative permittivity (Δε’/ε’) exhibits a clear linear correlation with the strain. This work provides a novel approach for the fabrication of low frequency dispersion and weak negative permittivity metacomposites.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
ORGANIC ELECTRONICS
·
2018
·
IF 3.68
Ciqun Xu,Yunpeng Qu,Guohua Fan,Huan Ren,Jiaqi Chen,Yao Liu,Yulin Wu,Runhua Fan
Metacomposites with conductive polymer matrix toward negative permittivity have promising applications in energy storage devices and electromagnetic shielding . In this paper, carbon nanotubes (CNTs)/polypyrrole (PPy) nanocomposites with different loadings of CNTs have been synthesized using a surface-initiated polymerization (SIP) method. Scanning electron microscopy (SEM) results indicate that conductive networks have constructed inside the nanocomposites by CNTs and PPy granules. A frequency switch of permittivity from positive to negative in pure PPy and CNTs/PPy nanocomposites with low CNTs loading (1 wt%) is observed, which can be analyzed by the Lorentz model. Besides, all negative permittivity behavior in the test frequency range (10–1000 MHz) is found in CNTs/PPy nanocomposites with higher CNTs content which can be easily tuned by adjusting the CNTs loading. Negative permittivity is considered arising from the plasma oscillation of delocalized electrons in conductive networks and could be fitted by Drude model. Furthermore, the equivalent circuit models, ac conductivity and dielectric loss are discussed.
研究领域:
材料科学
·
电磁学
·
高分子化学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2020
·Vol. 8
·期 9
·3029-3039
·
IF 7.059
Peitao Xie,Yifan Li,Qing Hou,Kunyan Sui,Chunzhao Liu,Xueyan Fu,Jiaoxia Zhang,Vignesh Murugadoss,Jincheng Fan,Yanpeng Wang,Runhua Fan,Zhanhu Guo
One-dimensional wires are the most common building blocks in metamaterials. In this study, zero-dimensional nanoparticles connected by tunneling networks were used to construct metamaterials, thus providing a more flexible alternative for designing the geometrical configuration of metamaterials, particularly in nanodevices. The composites with nickel nanoparticles@MnO were prepared by a bio-gel derived strategy. Nickel nanoparticles were not connected geometrically, but the conductive network had been already formed, which was a tunneling-dominated percolative phenomenon demonstrated by the first-principles calculation. Negative permittivity was achieved in the composites, as the low-frequency plasmonic state could be generated in the tunneling nickel-networks. At the same time, negative susceptibility was observed due to the diamagnetism of the tunneling current loops. Electromagnetic simulations indicate that the composites have the potential for electromagnetic shielding (only 0.25 mm in thickness). It is believed that this study not only fills up the research gap in the influence of the tunneling effect on negative electromagnetic parameters but also opens up another way of preparing metamaterials by using zero-dimensional nanoparticles instead of one-dimensional wires.
研究领域:
材料科学
·
电磁学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Advanced Composites and Hybrid Materials
·
2024
·Vol. 8
·期 1
·1-13
·
IF 23.2
Mu Zuxiang,Sun Yinuo,Qin Jiachen,Shen Zhaocun,Liang Gemeng,Zou Jinshuo,Lan Di,Xie Peitao
Negative permittivity materials hold immense potential in the field of sensing due to their high sensitivity. As the next generation of sensors moves toward flexible and wearable designs, conventional negative permittivity materials, which are predominantly based on rigid metal conductive networks, struggle to achieve the necessary flexibility. In this study, we synthesized Ni x /C/SiO 2 flexible composite films by electrospinning and high-temperature pyrolysis. Using polyacrylonitrile (PAN) as the precursor, along with nickel acetate tetrahydrate and tetraethyl orthosilicate, the material underwent carbonization to form a dual-phase carbon-nickel network, establishing a flexible conductive framework. A relatively low carbonization temperature was employed to maintain the flexibility of the carbon network, avoiding excessive graphitization that could compromise flexibility. To ensure sufficient carrier concentration within the system, Ni was introduced, while the addition of SiO 2 not only enhanced the flexibility of the composite fiber membrane but also strengthened the positive permittivity effect, allowing for precise tuning of the negative permittivity. The composite films exhibit excellent negative dielectric properties of about − 2000 and conductivity up to 0.018 (Ω·cm) −1 . Our research offers a viable approach for introducing flexibility into negative permittivity materials, thereby advancing their potential applications in the sensing field.
研究领域:
材料科学
·
传感器技术
✓ 已验证
产品关联
DOI
高影响因子
ECS Journal of Solid State Science and Technology
·
2019
·Vol. 8
·期 10
·N141
·
IF 1.795
Guangyue Shi,Yunpeng Qu,Guohua Fan,Yao Liu
The CNTs-CBs nano-units composed of carbon nanotubes (CNTs) and carbon black (CBs) have been prepared by electrostatic self-assembly. Herein, the CNTs-CBs/PS composites with different CNTs-CBs contents were prepared. The negative permittivity behavior was observed when three-dimensional conductive network was constructed by CNTs-CBs. Tunable and weakly negative permittivity originated from the low frequency plasmonic state which was collective electrons oscillation in CNTs-CBs network. The Jonscher's power law and Drude model were used to analyze the dielectric behavior and conductive mechanism changing. This work has broadened the applications of carbonaceous materials and polymers in the field of metamaterials.
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
·
2017
·
IF 2.986
Guohua Fan,Peitao Xie,Zhongyang Wang,Yunpeng Qu,Zidong Zhang,Yao Liu,Runhua Fan
Titanium nitride (TiN) with high-temperature plasmonic property can be a promising candidate for metamaterials at radio-frequency region. In this paper, pure TiN powders were pretreated by a facile oxidation process . The introduced titanium oxide was in favor of sintering of TiN, and further controlled the dielectric properties of TiN bulks. The radio-frequency (10 MHz-1 GHz) permittivity spectra of the obtained samples were investigated in detail. Negative permittivity was achieved using TiN based ceramic and it was tailorable by the oxidation temperatures of powders before sintering. The negative permittivity induced by plasma oscillations of conductive electrons was analyzed by Drude model. Interestingly, the zero-crossing points of permittivity from negative to positive were depend on the porous microstructure and weakly conductive titanium oxynitride , as well as the scattering effect by grain boundaries and impurity atoms. The conduction loss is dominant in determining the high dielectric loss. The realization of tunable negative permittivity using TiN gives a new and simple method to achieve negative electromagnetic parameters in single-phase materials.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
Advanced Composites and Hybrid Materials
·
2022
·Vol. 5
·期 3
·2369-2377
·
IF 11.806
Wang Zhipeng,Yin Kuan,Zhang Yuliang,Sun Kai,Xie Longjie,Cong Mengyang,Cao Shengjia,Lei Yanhua,Li Xiaofeng,Fan Runhua
In recent years, random composites with negative permittivity have been widely concerned owing to their unique properties and broad application prospects. In this paper, Ti 3 C 2 T x /carbonized wood (CW) composites with weakly negative permittivity were prepared by using CW as matrix and two-dimensional layered Ti 3 C 2 T x as the functional filler. The results of dielectric properties indicated that when the content of Ti 3 C 2 T x was 42.5 wt%, three-dimensional conductive networks were formed universally on the surface and inside the CW matrix. Meanwhile, the conduction mechanism changed from jumping conduction to metal-like conduction. Besides, the permittivity values of Ti 3 C 2 T x /CW composites changed from positive to negative and significantly reduced to the range of −65 to −35. This unique phenomenon was owing to the total electron concentration in the Ti 3 C 2 T x /CW composite being diluted equivalently, resulting in the decrease of plasma frequency, thus showing a weakly negative permittivity. This work provides a new strategy to determine the suitable content of conductive filler using percolation theory. Furthermore, the original fantastic structure properties of Ti 3 C 2 T x and wood also opened a new way for designing metacomposites, which has very important research value and far-reaching research significance. Graphical abstract Weakly negative permittivity achieved in two-dimensional Ti 3 C 2 T x /carbonized wood metacomposites.
研究领域:
材料科学
·
电磁学
✓ 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）