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, $d_0^{\prime }\sim 10$ and $d_0^{\prime \prime }\sim 9.2$ Å. 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.