Communication—Function-Oriented Design of 3D Carbon Networks Toward Negative Permittivity at kHz Frequencies

Abstract Three-dimensional (3D) carbon networks composed of graphene (GR) and carbon nanotube (CNT) were constructed in copper calcium titanate (CCTO) in order to realize negative permittivity behavior. The results show that negative permittivity can be obtained at kHz frequencies above percolation threshold when 3D carbon networks are successfully constructed. Negative permittivity originates from the low-frequency plasmonic state which is explained by the Drude model. The magnitude of negative permittivity was tuned between 105 and 106 which significantly correlates with concentration of free carriers. Moreover, the reactance spectra clarify the inductive character of negative permittivity materials.

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Tailorable epsilon-negative and epsilon-near-zero behavior of TiC/CCTO metacomposites: Low-frequency plasma oscillation

Functional Materials Letters ◽

10.1142/s1793604721500156 ◽

2021 ◽

pp. 2150015

Author(s):

Baogang Ding ◽

Yunpeng Qu ◽

Kai Sun ◽

Runhua Fan

Keyword(s):

Plasma Oscillation ◽

Three Dimensional ◽

Low Frequency ◽

Calcium Titanate ◽

Negative Permittivity ◽

Free Electrons ◽

Frequency Plasma ◽

Collective Plasma ◽

Negative Formula ◽

Epsilon Near Zero

Epsilon-negative ([Formula: see text]) and epsilon-near-zero (ENZ) property was demonstrated in titanium carbide/copper calcium titanate (TiC/CCTO) metacomposites. Benefiting from the moderate concentration of free electrons in TiC filler and its adjustable three-dimensional (3D) networks, weakly negative permittivity ([Formula: see text]200 at 20 MHz) was achieved. Not only that, tailoring the negative permittivity of metacomposites from [Formula: see text]200 to [Formula: see text]2060, [Formula: see text]4200, [Formula: see text]14000 and [Formula: see text]70000 at 20 MHz was realized by simply increasing TiC content. Besides, Drude model was used to explain the radio-frequency (RF) negative permittivity and quantified the collective plasma oscillation in TiC networks.

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Negative Permittivity Behavior in Silver/Polyaniline Metacomposites Induced by the Low-Frequency Plasmonic Oscillation

10.21203/rs.3.rs-239025/v1 ◽

2021 ◽

Author(s):

Jiahong Tian ◽

Runhua Fan ◽

Zongxiang Wang ◽

Jiahao Xin ◽

Zhongyang Wang

Keyword(s):

Synthesis Method ◽

Low Frequency ◽

In Situ Synthesis ◽

Negative Permittivity ◽

Free Electrons ◽

Dominant Effect ◽

Equivalent Circuit Analysis ◽

Inductive Character ◽

Percolation Network

Abstract Silver/polyaniline (Ag/PANI) composites were prepared by an in-situ synthesis method. Interestingly, the permittivity changed from positive to negative along with the formation of percolation network. The plasma oscillations of free electrons from the network made a dominant effect on the negative permittivity behavior. Further investigation based on equivalent circuit analysis revealed that the composites with negative permittivity presented inductive character. The epsilon-negative composites can be applied to electromagnetic shielding, absorbing and attenuation.

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Radio-frequency negative permittivity of carbon nanotube/copper calcium titanate ceramic nanocomposites fabricated by spark plasma sintering

Ceramics International ◽

10.1016/j.ceramint.2019.09.213 ◽

2020 ◽

Vol 46 (2) ◽

pp. 2261-2267 ◽

Cited By ~ 14

Author(s):

Chuanbing Cheng ◽

Yulin Wu ◽

Yunpeng Qu ◽

Rongwei Ma ◽

Runhua Fan

Keyword(s):

Carbon Nanotube ◽

Radio Frequency ◽

Spark Plasma Sintering ◽

Calcium Titanate ◽

Negative Permittivity ◽

Plasma Sintering ◽

Spark Plasma ◽

Titanate Ceramic ◽

Ceramic Nanocomposites

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Low frequency plasmonic state and negative permittivity spectra of coagulated Cu granular composite materials in the percolation threshold

Applied Physics Letters ◽

10.1063/1.4804379 ◽

2013 ◽

Vol 102 (18) ◽

pp. 181904 ◽

Cited By ~ 67

Author(s):

Takanori Tsutaoka ◽

Teruhiro Kasagi ◽

Shinichiro Yamamoto ◽

Kenichi Hatakeyama

Keyword(s):

Composite Materials ◽

Percolation Threshold ◽

Low Frequency ◽

Negative Permittivity ◽

Granular Composite

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Tailorable negative permittivity of graphene-carbon nanotube/copper calcium titanate metacomposites

Ceramics International ◽

10.1016/j.ceramint.2020.12.142 ◽

2020 ◽

Author(s):

Rongwei Ma ◽

Chuanbing Cheng ◽

Yunpeng Qu ◽

Runhua Fan

Keyword(s):

Carbon Nanotube ◽

Calcium Titanate ◽

Negative Permittivity

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A General Route to Prepare One- and Three-Dimensional Carbon Nanotube/Metal Nanoparticle Composite Nanostructures

Langmuir ◽

10.1021/la063246b ◽

2007 ◽

Vol 23 (11) ◽

pp. 6352-6357 ◽

Cited By ~ 45

Author(s):

Xiaoge Hu ◽

Tie Wang ◽

Liang Wang ◽

Shaojun Guo ◽

Shaojun Dong

Keyword(s):

Carbon Nanotube ◽

Three Dimensional ◽

Metal Nanoparticle ◽

Composite Nanostructures

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Understanding the low frequency response of carbon nanotube thermoacoustic projectors

Journal of Sound and Vibration ◽

10.1016/j.jsv.2021.115940 ◽

2021 ◽

Vol 498 ◽

pp. 115940

Author(s):

Prashant Kumar ◽

Rammohan Sriramdas ◽

Ali E. Aliev ◽

John B. Blottman ◽

Nathanael K. Mayo ◽

...

Keyword(s):

Carbon Nanotube ◽

Frequency Response ◽

Low Frequency

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Three-dimensional spherical composite of layered double hydroxides/carbon nanotube for ethanol electrocatalysis

Applied Clay Science ◽

10.1016/j.clay.2020.105964 ◽

2021 ◽

Vol 202 ◽

pp. 105964

Author(s):

Xiaotong Yang ◽

Yibo Gao ◽

Zhenzhen Zhao ◽

Ye Tian ◽

Xianggui Kong ◽

...

Keyword(s):

Carbon Nanotube ◽

Layered Double Hydroxides ◽

Three Dimensional ◽

Double Hydroxides

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Dual percolations of electrical conductivity and electromagnetic interference shielding in progressively agglomerated CNT/polymer nanocomposites

Mathematics and Mechanics of Solids ◽

10.1177/10812865211021460 ◽

2021 ◽

pp. 108128652110214

Author(s):

Xiaodong Xia ◽

George J. Weng

Keyword(s):

Experimental Data ◽

Electrical Conductivity ◽

Carbon Nanotube ◽

Percolation Threshold ◽

Polymer Nanocomposites ◽

Electromagnetic Interference ◽

Effective Medium Theory ◽

Scale Model ◽

Shielding Effectiveness ◽

Emi Shielding

Recent experiments have revealed two distinct percolation phenomena in carbon nanotube (CNT)/polymer nanocomposites: one is associated with the electrical conductivity and the other is with the electromagnetic interference (EMI) shielding. At present, however, no theories seem to exist that can simultaneously predict their percolation thresholds and the associated conductivity and EMI curves. In this work, we present an effective-medium theory with electrical and magnetic interface effects to calculate the overall conductivity of a generally agglomerated nanocomposite and invoke a solution to Maxwell’s equations to calculate the EMI shielding effectiveness. In this process, two complex quantities, the complex electrical conductivity and complex magnetic permeability, are adopted as the homogenization parameters, and a two-scale model with CNT-rich and CNT-poor regions is utilized to depict the progressive formation of CNT agglomeration. We demonstrated that there is indeed a clear existence of two separate percolative behaviors and showed that, consistent with the experimental data of poly-L-lactic acid (PLLA)/multi-walled carbon nanotube (MWCNT) nanocomposites, the electrical percolation threshold is lower than the EMI shielding percolation threshold. The predicted conductivity and EMI shielding curves are also in close agreement with experimental data. We further disclosed that the percolative behavior of EMI shielding in the overall CNT/polymer nanocomposite can be illustrated by the establishment of connective filler networks in the CNT-poor region. It is believed that the present research can provide directions for the design of CNT/polymer nanocomposites in the EMI shielding components.

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