Linear specific heat of carbon nanotubes

The specific heat and thermal conductivity of millimeter-long aligned carbon multiwall nanotubes (MWNT’s) have been measured. As a rolled-up version of graphene sheets, a MWNT of a few tens nm diameter is found to demonstrate a strikingly linear temperature-dependent specific heat over the entire temperature range measured (10–300 K). The results indicate that interwall coupling in MWNT’s is rather weak compared with its parent form, graphite, so that one can treat a MWNT as a few decoupled two-dimensional single wall tubules. The thermal conductivity is found to be low, indicating the existence of substantial amounts of defects in the MWNT’s prepared by a chemical-vapor-deposition method.