Quantum effects in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with He4

Abstract

The radial thermal expansion αr of bundles of single-walled carbon nanotubes saturated with He4 impurities to the molar concentration 9.4% has been investigated in the interval 2.5–9.5K using the dilatometric method. In the interval 2.1–3.7K αr is negative and is several times higher than the negative αr for pure nanotube bundles. Most likely this points to He4 atom tunneling between different positions in the nanotube bundle system. The excess expansion was reduced with decreasing He4 concentration.