Cyclic transformation in shape and crystal structure of C60 microcrystals

The cyclic transformations in shape and crystal structure of C60 microcrystals in dispersion are experimentally demonstrated by changing the dispersion solvent medium, and keeping the dispersion under ultrasonication. The shape of C60 microcrystals was changed from as-grown rod-shape to hexagonal disc-shape, then to belt-shape, and again back to rod-shape. The transformation processes were investigated by means of TEM, XRD and FT-IR measurements. As a results, the present transformation is regarded to be a crystal-to-crystal phase transition induced by the exchange of the dispersion medium, which is finally ascribed to weak intermolecular interactions between C60s inside the crystal.