Phase transformations in pressure polymerized <f>C60</f>

Differential Scanning Calorimetry and infra-red spectroscopy have been used to study the depolymerization of the two pressure polymerized phases of C60, i.e., rhombohedral (R) and orthorhombic (O) into monomeric C60 at <f>p=1</f> 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 C60 was sketched in, using experimental and literature data. [Copyright &y& Elsevier]