Diamond Phase Transitions at Nanoscale

Surface graphitization of ozone-treated detonation nanodiamonds

“…A similar catalytic effect of oxygen was proposed for graphitization of diamond crystals . Oxygen may promote a new route for diamond conversion into sp 2 forms . In the present case, according to the total pressure in the vacuum chamber during annealing, the partial pressure of O 2 cannot exceed 8 × 10 −7 Torr.…”

Surface Modifications of Nanodiamonds and Current Issues for Their Biomedical Applications

“…The graphitization mechanism is strongly sensitive to the presence of non-diamond carbon at the NDs surface [145]. Indeed, detonation NDs underwent purification procedures which can differ from a supplier to another (Part 4.2).…”

“…Graphitization kinetics for submicron diamond and NDs were compared, different graphitization rates were determined [154]. Moreover, the previous report demonstrates that activation energies differ for {110} and {111} crystallographic facets [145,159].…”

“…Finally, the graphitization could be catalyzed by metals as Fe or Co [142][143][144]. A recent review was devoted to diamond phase transitions at nanoscale [145]. For nanodiamond, the graphitization process can lead to a full transformation into onion like carbon (OLC) structures formed by concentric closed graphitic shells.…”

Production of Nanodiamond Particles

“…The model was derived based on experimental data obtained from XRD and small-angle X-ray scattering (SAXS) of DND of different level of purification. But these models do not take into account surface functional groups present on DND due to different oxidation treatments of detonation soot (Baidakova & Vul, 2007;Kuznetsov & Butenko, 2006). Later models suggested the presence of an intermediate layer between the perfect ND core and the sp 2 shell, resulting in a three-layer model of the DND particles (Aleksenskii et al, 1999;Baidakova & Vul, 2007;Hawelek et al, 2008;Kulakova, 2004;Palosz, et al, 2006).…”