Polymerized Fullerite Structures

We show in this Letter that heating under high pressure drives C₆₀ to new distorted crystalline phases that are metastable at room temperature and pressure. We report three different distortions that are essentially characterized by two nearest neighbor distances, d₀^'~10 and d₀^''~9.2 {}. The excellent accord with theoretical calculations supports the view that these new carbon phases can be understood as the long range order polymerization of C₆₀ through cycloaddition reactions that are at the origin of the shorter intermolecular distances.