Specific Heat and Thermal Conductivity of Solid Fullerenes

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Science  19 Feb 1993:
Vol. 259, Issue 5098, pp. 1145-1148
DOI: 10.1126/science.259.5098.1145


Evidence is presented that the lattice vibrations of compacted C60/C70 fullerite microcrystals consist predominantly of localized modes. Vibrational motions of the rigid molecules ("buckyballs") have been identified as well as their internal vibrations. Debye waves play only a relatively minor role, except below ∼4 kelvin. By comparison with other crystalline materials, for these materials the Einstein model of the specific heat and thermal conductivity of solids, which is based on the assumption of atoms (in this case, buckyballs) vibrating with random phases, is in much better agreement with the measurements than the Debye model, which is based on collective excitations.