Thermal-induced shape transformation of solvated C60 microcrystals

Phase transformation of solvated C60 microcrystals (MCs) was directly observed for the first time by use of thermal treatment to induce the phase transformation. C60 MCs were changed from bundle rod-shape to disc-shape, accompanied with the change of crystal structure from P63 symmetry to fcc symmetry. This kind of phase transformation included three steps in solvent medium: exchange of incorporated solvent, decomposition of old crystals, and formation of new crystals. It is not likely a kind of crystal-to-crystal phase transition assisted by incorporation of dispersing solvents but can be demonstrated as a decomposition-recrystallization process. The mechanism has been also tested by the thermal-induced phase transformation of C60 MCs from bundle shape to bipyramid shape.