Thermal measurements on multi-wall nanotubes

The electrical and mechanical properties of carbon nanotubes (CNTs) have been studied in depth at a single nanotube level; the same though cannot be said for their thermal properties. We have measured the thermal properties of multi-wall carbon nanotubes (MWNTs) using a temperature sensing scanned microscope probe. An arc-grown MWNT bundle is attached to a thermal probe with several individual MWNTs protruding from the end of the bundle. The system is operated in high vacuum and the temperature of the thermal probe may be controlled anywhere between 300 and 600 K. Then, under piezo displacement, the MWNT is brought into contact with a substrate surface (HOPG, highly oriented pyrolitic graphite). The substrate can be cooled from room temperature to similar to100 K. The heat flow down the MWNTs in contact with the substrate can be recorded as a function of the temperature difference across their ends. Simultaneous measurements of the electrical conductance and force applied to the nanotube are taken. The thermal and electrical conductance curves of different MWNTs are presented; the size of the conductance steps observed and the correlation between electrical and thermal conductance steps are discussed together with the effect of oxygen adsorption on the properties of the MWNTs.