Light Element Polycrystalline Structures Incorporating Micron to Nanosize Constituents

Abstract

Light element solids among which diamond, the nitrides of boron and aluminum and their polymorphs have received considerable research attention over the last decade, particularly since the discoveries of new nanosized structures known as bucky balls and fullerenes in many different forms. Concurent with the research activities certain light element materials have as films, bulk and composite structures with micro-or nanosized grains, moved closer to the engineering application stage. This effort will review three areas of particular interest. The current status of polycrystalline c-BN thick films and bulk structures of importance in such applications as high thermal conductivity substrates, high dielectric constant capacitors, laser targets, electron emission cathodes and substrates for thin film deposition, will be reviewed first. In the second part an attempt will be made to give a (non-exhaustive) overview of the current efforts to synthesize and characterize carbon, boron nitride and other fullerenes. The third part will deal with the possible role that light element nanostructures may play in hydrogen storage, a technical challenge of great importance to a global society and to mankind at large.