ORIENTATIONAL PHASE-TRANSITION IN C-60 SINGLE-CRYSTAL UNDER HIGH-PRESSURE

By using a piston-cylinder type hydrostatic high-pressure unit, the el ectrical de conductance of bulk C-60 single crystal was measured in th e pressure range of 0 to 0.6 GPa at 290 K. With increasing pressure, a discontinuous increase of the conductance was observed at the pressur e of 0.176 GPa, which can be ascribed to the orientational ordering ph ase transition. In the simple cubic phase, the increase of conductance with increasing pressure is faster than that in the face-centered-cub ic phase.