Variable step radial ordering in carbon onions

We analyse the radial distribution of atoms in carbon onions optimised using a combination of classical molecular dynamics and density functional theory. X-ray diffractograms of thermally annealed nanodiamonds are also exploited together with high-resolution transmission electron microscopy data published elsewhere. The internal radial ordering of atoms inside the onions was determined showing a gradual change of intershell separation as a function of radius. This change may result in a twisted internal structure of the onions. The influence of atomic defects appearing in the shells altering their curvature on the formation of twisted onions is discussed. (c) 2012 Elsevier B.V. All rights reserved.