Low-temperature heat capacity of fullerite C60 doped with nitrogen

Анотація

The heat capacity C_m of polycrystalline fullerite C₆₀ doped with nitrogen has been measured in the temperature interval 2-13 K. The contributions to the heat capacity from translational lattice vibrations (Debye contribution), orientational vibrations of the C₆₀ molecules (Einstein contribution), and from the motion of the N₂ molecules in the octahedral cavities of the C₆₀ lattice have been estimated. However, we could not find (beyond the experimental error limits) any indications of the first-order phase transformation that had been detected earlier in the dilatometric investigation of the orientational N₂-C₆₀ glass. A possible explanation of this fact is proposed.