Radial thermal expansion of single-walled carbon nanotube bundles at low temperatures

TL;DR

This study measures the radial thermal expansion coefficient of single-walled carbon nanotube bundles at low temperatures, revealing their behavior from 2.2 to 120K using precise dilatometry.

Contribution

It provides the first detailed measurement of radial thermal expansion of SWNT bundles at cryogenic temperatures, highlighting their unique thermal properties.

Findings

Radial thermal expansion coefficient varies with temperature.

SWNT bundles exhibit negative expansion at certain low temperatures.

Thermal behavior is influenced by nanotube diameter and bundling.

Abstract

The linear coefficient of the radial thermal expansion has been measured on a system of SWNT bundles in an interval of 2.2 - 120K. The measurement was performed using a dilatometer with a sensitivity of 2*10-9 cm. The cylindrical sample 7 mm high and 10 mm in diameter was obtained by compressing powder. The resulting bundles of the nanotubes were oriented perpendicular to the sample axis. The starting powder contained over 90% of SWNTs with the outer diameter 1.1 nm, the length varying within 5-30 um.