Heat capacity measurements and thermodynamic studies of the new compound C 60

Abstract

Heat capacity of the new compound C 60 was measured by using a laboratory-made adiabatic calorimeter between liquid helium temperature and room temperature. A phase transition phenomenon was observed as a large heat capacity anomaly extending from 180 to 260 K. The fact that the anomaly has two peaks at 250 and 255 K indicates a complicated mechanism of the phase transition and/or some effects of purity, multi-phases in the sample. The values of enthalpy and entropy of transition were estimated as 6.7 kJmol −1 and 28 JK −1mol −1, respectively. The normal portion of the heat capacity curve as a whole is very similar to that of graphite. In the lowest temperature region, however, the heat capacity of C 60 is much larger than that of graphite. Molecular motion in the crystal of C 60 is discussed concerning with the lattice vibrations.