THERMODYNAMIC PROPERTIES OF C_(60) SINGLE CRYSTALS AT LOW TEMPERATURE

The structure of C60) single crystals at room temperature was determined to be face-centered-cubic (fcc) by X-ray diffraction. The thermodynamic properties at low temperature of C60 single crystals grown by vapor transport method were studied by means of differential-scanning-calorimetry (DSC). The possible origin of the anomalous endothermal peaks of orientational transition is solvation whose effect is estimated to be 1.13 J · g-1. The procedure to purify the starting C60 powder was improved. The DSC measurement on pure C60 single crystals shows that the orientational phase transition occurs at 261K. The latent heat of the transition is approximately 8.39J·g-1. The activation energy of the transition is estimated to be about 190kJ· mol-1.