Published online by Cambridge University Press: 15 February 2011
A thermodynamic model describing the co-existence of phases at orientational phase transition in solid fullerenes is developed. It is shown that for such a transition in fullerene C60 characterized by the comparatively low enthalpy, heterophase fluctuations can lead to the wide temperature region of the phase co-existence within about 30 K below the 260 K transition point, and mainly determine the anomalies of thermodynamic characteristics observed within that region. By comparison of the theoretical dependence obtained on this basis with the experimental data on the x-ray diffraction and heat capacity measurements for C60, the energetical characteristics of the heterophase cluster formation are evaluated. The relative contribution of homophase and heterophase fluctuations to breaking the orientational order is discussed.