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Negative permittivity derived from inductive characteristic in the percolating Cu/EP metacomposites

Sun, K; Xin, J; Li, Y; Wang, Z; Hou, Q; Li, X; Wu, X; ... Leong Choy, K; + view all (2019) Negative permittivity derived from inductive characteristic in the percolating Cu/EP metacomposites. Journal of Materials Science & Technology , 35 (11) pp. 2463-2469. 10.1016/j.jmst.2019.07.015. Green open access

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Abstract

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.

Type: Article
Title: Negative permittivity derived from inductive characteristic in the percolating Cu/EP metacomposites
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.jmst.2019.07.015
Publisher version: https://doi.org/10.1016/j.jmst.2019.07.015
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions
Keywords: Negative permittivity; Epsilon-negative materials; Percolating composites; Metacomposites; Metamaterials
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > MAPS Faculty Office
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > MAPS Faculty Office > Institute for Materials Discovery
URI: https://discovery.ucl.ac.uk/id/eprint/10085472
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