An internal-friction study of C₆₀crystal intercalated with O₂

After a C60crystal was intercalated with O2, the internal-friction peak due to the orientational relaxation of the C60molecules shifted to a lower temperature. Also, the activation energy decreased, by 26 meV. These results indicate that the depth of the orientational potential well is changed by the O2intercalation. This change is assumed to be due to the electrostatic interaction between O2and C60molecules. The decrease of the order-disorder phase transition temperature, which is by about 20 K, can also be explained using this model.