Structures of Carbon Nanocrystals

Single-crystal electron nanodiffraction patterns have been obtained from nanocrystals of various phases formed within carbonaceous balls produced by chemical vapor deposition (CVD). For the face-centered cubic phase, n-diamond, with cell dimension a = 0.36 nm, the relative intensities of the (200) reflection (forbidden for the diamond structure) and the (111) reflection suggest that the structure may include hydrogen atoms, and theoretical analyses support this possibility. There is evidence for a body-centered cubic phase with a = 0.31 nm, and the incorporation of hydrogen in this structure is suggested. Small amounts of hexagonal diamond, i-carbon, and other cubic phases are also present.