Phase transformations in pressure polymerized C60

Differential Scanning Calorimetry and infra-red spectroscopy have been used to study the depolymerization of the two pressure polymerized phases Of C-60, i.e., rhombohedral (R) and orthorhombic (0) into monomeric C-60 at p = 1 atm. The depolymerization enthalpies obtained were 10.3 +/- 0.5 and 20.1 +/- 0.6 kJ/mol for R-, O-phases, respectively. The R-phase, prepared at 1025-1050 K and 6 GPa ('magnetic carbon') demonstrated the depolymerization behaviour, similar to the typical R-phase. Part of the p-T-phase diagram Of C-60 was sketched in, using experimental and literature data. (C) 2003 Elsevier B.V. All rights reserved.