AN X-RAY-DIFFRACTION STUDY OF C60 UP TO 28 GPA

C60 has been investigated up to 28 GPa in a diamond anvil cell by x-ray diffraction, using both film and an imaging ate. Above 10 GPa, significant broadening of the diffraction lines was observed with a ring of diffuse scattering remaining at 23 GPa. At 28 GPa, the diffraction pattern was featureless due to the highly disorganised nature of the material. These results are consistent with the formation of C60 agglomerates above 10 GPa and of the collapsed fullerite (CF) phase above 23 GPa. The bulk modulus of the simple cubic (sc) phase at ambient pressure was determined to be 14.4(1.8) GPa based on the high pressure pV data.