Abstract

The potential impact of encapsulated molecules on the thermal properties of individual carbon nanotubes (CNTs) has been an important open question since the first reports of the strong modulation of electrical properties in 2002.  However, thermal property modulation has not been demonstrated experimentally because of the difficulty of realizing CNT-encapsulated molecules as part of thermal transport microstructures. Here we develop a nanofabrication strategy that enables measurement of the impact of encapsulation on the thermal conductivity and thermopower of single CNT bundles that encapsulate C60, Gd@C82 and Er2@C82.  Encapsulation causes 35–55% suppression in the conductivity and approximately 40% enhancement in the thermopower compared with the properties of hollow CNTs at room temperature. Measurements of temperature dependence from 40 to 320 K demonstrate a shift of the peak in the thermal conductivity to lower temperature. The data are consistent with simulations accounting for the interaction between CNTs and encapsulated fullerenes.