The emerging field of nanoengineering requires design of nanoscale structures with determined physical and chemical properties. It is important that basic building blocks for these structures are easily accessible, for example, as nanodiamonds and nanotubes. Both structural components are unique materials with diverse electronic properties depending on their size and morphologies. The feasibility of designing composites of nanodiamond with carbon nanotube as well as their electronic properties will be discussed.
Depending on a nanotubes size and morphology, some types of open nanotubes can be chemically connected with different diamond surfaces, atom to atom. So far, the following nanotube/nanodiamond combinations have been designed: (12,0) and (6,0) nanotubes with cubo-octahedron particles; (5,5) nanotube and a pentaparticle. All structures are mechanically stable with all bonds saturated. An especially low mismatch (2.5%) exists between the armchair (5,5) nanotube and a pentaparticle surface when the <011> pentaparticle axis coinciding with the tube axis (see the figure). Fabrication of these structures could potentially be achieved using self-assembly of the components in microemulsions or by laser irradiation.
Different types of heterojunctions can be designed which could be used for logic or memory nanodevices by combining semiconducting or metallic nanotubes with diamond clusters. Another possible application of the tube/nanodiamond composite, illustrated in the figure, may be a tip for a field emitting display. Currently nanotubes have potential as a field emitting material and the above design of a nanotube capped with nanodiamond may reduce tube erosion and increase device lifetimes.
Electronic and optical properties of nanostructures consisting of carbon nanocones will be also briefly discussed.