High dielectric permittivity in C-60 crystals

The complex dielectric response in C-60 crystal reveals very high real part of the dielectric constant epsilon' > 100 at 300 K and < 500 Hz. This very large polarizability results from a thermally activated process (occurring at 200 K < T < 300 K) with two different activation energies of 0.41 eV fo r T < 260 K and 0.33 eV associated with extra addition polarization for T > 250 K. We have found 0.75 < alpha < 0.9, 55 < Delta epsilon' < 70, and 5 < epsilon'(infinity) < 7 by a Cole-Cole model analysis. (C) 2000 Elsevier Sc ience B.V. All rights reserved.