Dislocation drag in the low-temperature phase of C60 fullerite due to orientational relaxation of the molecules

The interaction of edge dislocations with pentagonal (p) and hexagonal (h) orientation states of the molecules in the low-temperature simple cubic phase of C-60 fullerite is discussed. The temperature interval considered is T-g < T < T-c, where T-c = 260 K is the phase transition temperature and T-g = 90 K is the orientational glass point. The nonuniform distribution of the h configurations around a sessile dislocation line is described, and the starting force F-s(T) needed to break the dislocation away from the cloud of h configurations formed by it is determined. The dynamic drag force F-D(T,V) arising as a result of thermally activated transitions between the p and h configurations under the influence of the elastic field of a dislocation moving at a constant velocity V is calculated and analyzed. (C) 2000 American Institute of Physics. [S1063-777X(00)00703-9].