Diamond has always been a material that attracted a lot of interest among researchers ofvarious fields. Not only its valuable properties like the hardness, inertness and electronic behaviour but also its structural properties such as surface structure and lattice defects are of great interest. The existence of nanoscale diamond in the interstellar dust was also discussed.
Especially at the nanoscale diamond exhibits a variety of exceptional features. Among them, the easy reconstruction of the particle surface and the transformation into carbon onions play an important role. In a size range up to ~10 nm the thermodynamic stability of sp2 and sp3 carbon shows only slight differences and the transformation of diamond into carbon onions can be achieved by electron irradiation or thermal treatment. Here we will discuss some mechanistic issues of this transformation and the properties of the resulting materials.
On the other hand, the production of nanoscale diamond itself represents an interesting task. Production methods include the milling of larger diamond crystals, the shock wave transformation of graphite as well as the production of so-called detonation diamond from explosives. This technique was developed in Russia in the 1960s. We are working on the deagglomeration and solubilisation of the primary nanocrystalline diamond particles. Here we discuss mechanical and chemical methods of deagglomeration, namely the beads milling, the beads assisted sonic disintegration and the reductive hydroboration. Altogether, nanoscale diamond, carbon onions and other nanoscale carbons are important for the discussion of the production of larger scale carbon materials with well-defined properties and the understanding of their crystallographic properties.