Preparation and study of high-pressure phases of C60 fullerene

Several phase modifications of C60 were obtained using 3 GPa pressure-treatment of fullerene at different temperatures in 100–900 C range. The substances possessed very different properties and were thoroughly investigated. In the present work we report optical data on the material that can be associated with the mixture of rhombohedral and tetragonal high-pressure phases. It was synthesized when treatment temperature was only a little lower than the high-temperature limit of C60 stability. The phase exhibited extremely rich infrared and Raman spectra as well as luminescence spectra of an unusual shape. The spectra show that the symmetry of vibrational and electronic transitions in the prepared carbon architecture was substantially reduced in comparison with that of buckyballs. The changes apparently originate from carbon-carbon interaction in the same or adjacent molecules which can be expected for compound formed by disk-shaped fullerene clusters.