On the Structure of i-Carbon

M.J. BUCKNUM; C.J. PICKARD; I. STAMATÍN; EDUARDO ALBERTO CASTRO

J Theor Comp Chem

Año: 2006 vol. 5 p. 175 - 185

            In the carbon science literature, there have been various reports over the previous few decades of potentially novel crystalline forms of carbon emerging as nanometer scale fragments recovered from the explosive remnants of heated, shock compressed graphite and other precursors of C. Two nanometric forms of C that are particularly prominent in these studies are called n-diamond and i-carbon. In previous work by us, we have shown that the commonly observed diffraction pattern of n-diamond nanocrystals recorded by several research groups around the world, is consistent with the calculated diffraction pattern of a novel form of carbon we have proposed called glitter. Glitter is a tetragonal allotrope of carbon with a density of about 3.08 g/cm3, and the density functional theory-CASTEP (DFT-CASTEP) optimized lattice parameters given as a = 0.2560 nm and c = 0.5925 nm. In addition to the diffraction evidence for n-diamond having the glitter structure, the calculated band structure of glitter (DFT-CASTEP) shows it to be metallic like the observed electrical characteristics of n-diamond. In this communication, we report on a comparison of the diffraction pattern observed for i-carbon by the investigative team of Yamada et al. in 1994, with the calculated diffraction pattern of glitter based upon lattice parameters optimized in by the DFT-CASTEP method by Pickard et al. as was reported separately in the n-diamond comparison described above in 2005.