THE LOW-TEMPERATURE SYMMETRY CHANGE OF C-60 - A HIGH-RESOLUTION X-RAY-DIFFRACTION INVESTIGATION

High resolution X-ray diffraction has been used to investigate the ori gin of both, the unexpected presence and the diverging temperature evo lution of some specific reflections in the low temperature phase (Pa(3 ) over bar) of fullerene C-60. The results indicate that these reflect ions are most likely associated with the existence of degenerated doma ins of Pa(3) over bar symmetry as proposed initially by Moret et al. a nd not to the development of a lower symmetry phase below 160 K. They do not either correspond to a precursor effect (short range order) of a virtual phase transition which would occur below T-g. Copyright (C) 1996 Elsevier Science Ltd