Structural studies of nanodiamond by high-energy X-ray diffraction

The atomic scale structure of explosive diamond nanoparticles has been studied using high-energy X-ray diffraction. The diffraction data have been converted to the real space representation in the form of the radial distribution function. Spherical and truncated octahedron nanodiamond clusters containing from 729 to 1182 atoms have been computer generated and then relaxed using the molecular dynamics method with the reactive empirical bond order potential for carbon-carbon interaction and the Lennard-Jones potential with parameters for inter-layer interactions. Validity of such constructed models has been verified by comparison of the simulations and the experimental data in both real and reciprocal space. The obtained results show that the structure of the investigated diamond nanoparticles cannot be satisfactorily described in terms of the model based on the perfect diamond lattice. The core-shell model with an average size of 22.5-23.4 Å, consisting of the diamond core and the graphite-like shell, accounts very well for the experimental data.