ISSN:
1090-6487
Keywords:
61.48.+c
;
72.80.Rj
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1134/1.567407
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