The kinetics of sorption and subsequent desorption of argon gas by powdered C60 was investigated at 58 to 290K. The temperature dependence of the Ar diffusion coefficients in fullerite was obtained using the measured characteristic times of sorption. The diffusion coefficients of Ar decrease monotonically with lowering temperature in the whole temperature range, what corresponds to the thermally activated diffusion of Ar atoms in fullerite. The glass transition in fullerite induced an order-of magnitude decrease in the activation energy of Ar diffusion in fullerite. This appeared to be because of new directions appeared due to the glass transition in which the barriers separating the interstitial voids in the C60 lattice were significantly lower.

The Effect of Glass Transition in Fullerite C60 on Ar Impurity Diffusion. Dolbin, A.V., Eselson, V.B., Gavrilko, V.G., Manzhelii, V.G., Vinnikov, N.A., Basnukaeva, R.M.: Fizika Nizkikh Temperatur, 2013, 39[4], 475-80