Linear specific heat of carbon nanotubes

The specific heat and thermal conductivity of millimeter-long aligned carbo n multiwall nanotubes (MWNT's) have been measured. As a rolled-up version o f graphene sheets, a MWNT of a few tens nm diameter is found to demonstrate a strikingly linear temperature-dependent specific heat over the entire te mperature range measured (10-390 K). The results indicate that interwall co upling 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 tu bules. The thermal conductivity is found to be low, indicating the existenc e of substantial amounts of defects in the MWNT's prepared by a chemical-va por-deposition method. [S0163-1829(99)50714-5].