Thermal-induced shape transformation of solvated C60 microcrystals

Phase transformation of solvated C-60 microcrystals (MCs) was directly observed for the first time by use of thermal treatment to induce the phase transformation. C-60 MCs were changed from bundle rod-shape to disc-shape, accompanied with the change of crystal structure from P6(3) 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 C-60 MCs from bundle shape to bipyramid shape. (C) 2013 Elsevier Ltd. All rights reserved.