Crystal structure and growth mechanism of unusually long fullerene (C₆₀) nanowires

Exceptionally long C-60 nanowires, with a length to width aspect ratio as large as 3000, are grown from a 1,2,4-trimethylbenzene solution of C-60. They have been formed to possess a highly unusual morphology, with each nanowire being composed of two nanobelts joined along the growth direction to give a V-shaped cross section. The crystal structure of these nanowires is found to be orthorhombic, with the unit cell dimensions of a = 10.2 angstrom, b = 20.5 angstrom, and c = 25.6 angstrom. Structural and compositional analyses enable us to explain the observed geometry with an anisotropic molecular packing mechanism that has not been observed previously in C-60 crystal studies. The nanowires have been observed to be able to transform into carbon nanofibers following high-temperature treatment, but the original V-shaped morphology can be kept unchanged in the,transition. A model for the nanowire morphology based upon the solvent-C-60 interactions and preferential growth directions is proposed, and potentially it could be extended for use to grow different types of fullerene nanowires.