Polymerized Fullerite Structures

We show in this Letter that heating under high pressure drives ${\mathrm{C}}_{60}$ 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, ${d}_{0}^{\ensuremath{'}}\ensuremath{\sim}10$ and ${d}_{0}^{\ensuremath{'}\ensuremath{'}}\ensuremath{\sim}9.2$ \AA{}. The excellent accord with theoretical calculations supports the view that these new carbon phases can be understood as the long range order polymerization of ${\mathrm{C}}_{60}$ through cycloaddition reactions that are at the origin of the shorter intermolecular distances.