CRYSTALLIZATION

Crystallization occurs by thermodynamic means and alternatively by kinetic means. Crystallization can occur rationally by nucleation and growth according to a template model, as in the GE process for the growth of single crystal diamond from graphite powder, or crystals can grow seemingly irrationally.........for example the growth of a single crystal of silicon nitride or germanium nitride, from the elements, in the seemingly impossible template of a phenacite pattern. Crystalline thin films of semiconductors and diamond can be grown by chemical vapor deposition or by epitaxial means. The microscopic details of crystal growth are well understood only with respect to molecular crystals and crystals grown on a strict template model. As powdered graphite assembles in to macroscopic single crystal diamond...........so one would suspect that nanotube cylinders might assemble in to single crystal hexagonites by an analogous process. Though such a scenario is speculative at the moment and would depend upon a cooperative nucleation and templating process of the nanotubes. Twinning of crystals occurs at times whereupon 2 separate but related polymorphs are joined into a single twinned crystal along a complementary crystallographic cell face. And it may be true that cubic diamond is joined to tetragonal glitter across the basal plane of each component unit cell........Although such a scenario is speculative at best and would depend upon a thorough microscopical examination for the model to ultimately be proved right or wrong.