Structural transformations of double-walled carbon nanotube bundle under hydrostatic pressure

TL;DR

This paper investigates how double-walled carbon nanotube bundles respond structurally to hydrostatic pressure, revealing different transformation mechanisms depending on their size and symmetry, with potential experimental signatures identified.

Contribution

It identifies distinct pressure-induced structural transformation mechanisms in DWNT bundles based on diameter and symmetry, including phase transitions and continuous deformations.

Findings

Small DWNT bundles show discontinuous volume change and then deform continuously.

Intermediate DWNT bundles undergo a complete collapse after a phase transition.

Larger DWNT bundles with certain symmetries exhibit two phase transitions.

Abstract

Three kinds of the response mechanisms to the external pressure have been found for double-walled carbon nanotube (DWNT) bundle, depending strongly on their average radius and symmetry. The small-diameter DWNT bundle undergoes a small discontinuous volume change, and then deform continuously. The intermediate-diameter DWNT bundle collapses completely after a structure phase transition (SPT). Significantly, two SPTs exist for the larger-diameter DWNT bundle if the outer tube has no $C_{6}$ or $C_{3}$ symmetry. It would be interesting to search for signatures of these different structural transformations by experimentally investigating mechanical, optical and thermal response functions of DWNT bundle.