Few Wall Carbon Nanotube Coils

Dekel Nakar dekelnakar@gmail.com ¹ Georgy Gordeev ² Eliézer R. de Oliveria ³ Ronit Popovitz-Biro ⁴ Katya Rechav ⁴ Patryk Kusch ² Leonardo D. Machado ⁵ Ado Jorio ⁶ Douglas S. Galvão ³ Stephanie Reich ² Ernesto Joselevich ¹

¹Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
²Department of Physics, Freie Universität Berlin, Berlin, Germany
³Applied Physics Department, University of Campinas - UNICAMP, Campinas, SP, Brazil
⁴Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
⁵Department of Physics, Federal University of Rio Grande do Norte, Natal, RN, Brazil
⁶Department of Physics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil

While various electronic components based on carbon nanotubes (CNTs) have been produced, a micron-scale planar induction coil has not been demonstrated yet. Our group previously created defect-free single-wall CNT coils, but short-circuiting between turns prevents the coils from acting as inductors. To overcome this limitation, here we explore the use of few-wall CNTs, in which the outer walls may act as sheathing for the inner walls. We show the successful formation of the first few-wall CNT coils with accessible ends, low defect densities and a µm-scale. We characterized their structural, optical and electrical properties using optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), top-view transmission electron microscopy (TEM), cross-sectional TEM, Raman spectroscopy and electrical measurements. The coils comprised CNTs of two, three and four walls with up to 163 turns and diameters between 1 and 5 µm. Based on the structural results, we suggest a formation mechanism for the coils, supported by molecular dynamics simulations. These ordered coils extend the known repertoire of self-organized structures of 1D nanomaterials. They are also promising candidates for inductive devices, and for manifesting other interesting properties, such as electromagnetism and superconductivity.

Structure of a few wall CNT coil. (a) SEM image. (b) AFM image. (c) Medium magnification TEM images of the cross-sectional lamella (taken from the location marked by the green line in b). (d) High magnification TEM image of the cross-sectional lamella, showing this is a few wall CNT coil (magnification of the purple rectangle in c).