Towards fractional-order capacitors with broad tunable constant phase angles: Multi-walled carbon nanotube-polymer composite as a case study

Agamyrat Agambayev, Karam Hani Rajab, Ali H. Hassan, Mohamed Farhat, Hakan Bagci, Khaled N. Salama

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

In this study, multi-walled carbon nanotube (MWCNT) filled Polyevinelidenefluoride-trifluoroethylene-chlorofluoroethylene (PVDF-TrFE-CFE) composites are used to realize fractional-order capacitors (FOCs). A solution-mixing and drop-casting approach is used to fabricate the composite. Due to the high aspect ratio of MWCNTs, percolation regime starts at a small weight percentage (wt%), 1.00 % .The distributed MWCNTs inside the polymer act as an electrical network of micro-capacitors and micro-resistors, which, in effect, behaves like a FOC. The resulting FOCs' constant phase angle (CPA) can be tuned from to by changing the wt% of the MWCNTs. This is the largest dynamic range reported so far at the frequency range from 150 kHz to 2 MHz for an FOC. Furthermore, the CPA and pseudo-capacitance are shown to be practically stable (with less than 1% variation) when the applied voltage is, changed between 500 µV and 5V. For a fixed value of CPA, the pseudo-capacitance can be tuned by changing the thickness of the composite, which can be done in a straightforward manner via the solution-mixing and drop-casting fabrication approach. Finally, it is shown that the frequency of a Hartley oscillator built using an FOC is almost 15 times higher than that of a Hartley oscillator built using a conventional capacitor.
Original languageEnglish (US)
Pages (from-to)065602
JournalJournal of Physics D: Applied Physics
Volume51
Issue number6
DOIs
StatePublished - Jan 22 2018

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