INFLUENCE OF OXYGEN ON CRYSTALLINE FULLERENE C-60 - A DSC STUDY

A C60 sample has been submitted to a 18 MPa oxygen pressure at room te mperature and DSC thermograms have been recorded as a function of the evacuating time under a primary vacuum at 315 K. These thermograms exh ibit the well-known phase transition at 258 K and also a lower-tempera ture broad effect whose temperature and enthalpy seem to depend on the oxygen concentration in the C60 powder. These observations support pr evious NMR work according to which the octahedral sites of C60 cubic l attice can be reversibly occupied by oxygen molecules; they reveal the resulting thermodynamic counterpart.