FULLERENE ALLOYS

The results of differential scanning calorimetry (DSC) and powder X-ra y diffraction (XRD) on C-60(x) - C-70(1-X) (0<X<1) fullerene alloys ar e presented. Samples have been prepared by solubilizing weighed amount s of C-60 and C-70 in toluene and then evaporating the solvent, and by subliming C-60 - C-70 powders under dynamic vacuum. Dilute alloys pre pared from toluene solution undergo the orientational transition at lo wer temperatures than pure C-60 and C-70, the depression of the transi tion temperature depending on the alloy fraction. These samples also e xhibit a large miscibility gap for 0.04<x<0.95. In contrast, alloys pr epared by sublimation are miscible in all proportions, at least in the high-temperature fee phase. The experimental solubilities are compare d with the calculated binary phase diagram, in which intermolecular in teractions are treated by the Girifalco potential.