Structural evolution and Raman study of nanocarbons from diamond nanoparticles

Nanocarbons with a variety of morphologies were found after diamond nanoparticles (ND) were annealed at a low temperature. The conversion of ND to nanocarbons is a process of structural evolution that causes increase of sp2 bonding structure and decrease of sp3 bonding structure in nanostructure. While being annealed, ND are converted to carbon onions and undergo phase transition in a series of ND → bucky diamond → carbon onions → graphitic ribbons. The structural evolution of nanocarbons reflects the higher stability of planar graphitic ribbons over carbon onions.