By means of topological arguments we predict a new class of 4-coordinated covalent carbon lattices having a hollow structure (hollow diamonds (HDs)). A calculation of their structural and elastic properties based on the Tersoff potential indicates a stability and hardness very close to, albeit smaller than diamond. However, the intercalation of the smallest HDs with either mono- or divalent ions is estimated to give new nanocomposite materials which are harder than diamond.

http://dx.doi.org/10.1007/BF02451606