New superhard phases for three-dimensional C-60-based fullerites

We have explored new possible phases of 3D C-60-based fullerites using semi empirical potentials and ab initio density functional methods. We have foun d three closely related structures-two body-centered orthorhombic and one b ody-centered cubic-having 52, 56, and 60 tetracoordinated atoms per molecul e. These 3D polymers result in semiconductors with bull; moduli near 300 GP a, and shear moduli around 240 GPa, which make them good candidates for new low density superhard materials.