Abstract
The behavior of the thermal conductivity k(T) of bulk faceted fullerite C60 crystals is investigated at temperatures T=8–220 K. The samples are prepared by the gas-transport method from pure C60, containing less than 0.01% impurities. It is found that as the temperature decreases, the thermal conductivity of the crystal increases, reaches a maximum at T=15–20 K, and drops by a factor of ∼2, proportional to the change in the specific heat, on cooling to 8 K. The effective phonon mean free path λ p, estimated from the thermal conductivity and known from the published values of the specific heat of fullerite, is comparable to the lattice constant of the crystal λ p∼d=1.4 nm at temperatures T>200 K and reaches values λp∼50d at T<15 K, i.e., the maximum phonon ranges are limited by scattering on defects in the volume of the sample in the simple cubic phase. In the range T=25−75 K the observed temperature dependence k(T) can be described by the expression k(T)∼exp(Θ/bT), characteristic for the behavior of the thermal conductivity of perfect nonconducting crystals at temperatures below the Debye temperature Θ (Θ=80 K in fullerite), where umklapp phonon-phonon scattering processes predominate in the volume of the sample.
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References
A. P. Ramirez, Condens. Matter News 3, 6, 9 (1994).
G. Pitsi, J. Caerels, and J. Thoen, Phys. Rev. B 55, 915 (1997).
J. E. Fischer, A. R. McGhie, J. K. Estrada et al., Phys. Rev. B 53, 11418 (1996).
R. C. Yu, N. Tea, M. B. Salamon et al., Phys. Rev. Lett. 68, 2050 (1992).
J. R. Olson, K. A. Topp, and R. O. Pohl, Science 259, 1145 (1993).
W. P. Beyermann, M. F. Hungley, J. D. Thompson et al., Phys. Rev. Lett. 68, 2046 (1992).
M. Tachibana, M. Michiyama, H. Sakuma et al., J. Cryst. Growth 166, 883 (1996).
J. M. Ziman, Electrons and Phonons, Clarendon, Oxford, 1963.
R. Berman, Thermal Conduction in Solids, Clarendon Press, Oxford, 1976 [Russian translation, Mir, Moscow, 1979].
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Pis’ma Zh. Éksp. Teor. Fiz. 65, No. 8, 651–656 (25 April 1997)