An ab initio study of the nickel-catalyzed transformation of amorphous carbon into graphene in rapid thermal processing

摘要: Ab initio molecular dynamics (AIMD) simulations are employed to investigate the chemical mechanism underlying Ni-catalyzed transformation of amorphous carbon (a-C) into graphene in rapid thermal processing (RTP) experiment directly grow on various dielectric surfaces via evaporation surplus Ni and C at 1100 °C (below melting point bulk Ni). It is found that a-C-to-graphene entails metal-induced crystallization layer exchange mechanism, rather than conventional dissolution/precipitation typically involved vapor deposition (CVD) growth graphene. The multi-layer can be tuned by changing relative thicknesses deposited a-C thin films. Our AIMD suggest easy with excess likely attributed formation a viscous-liquid-like Ni-C solution within temperature range 900-1800 K faster diffusion atoms above 600 K. Even room temperature, sp(3)-C quickly converted sp(2)-C course simulation, graphitic occur low temperature. When as high 1200 K, grown structures reversely dissolve Ni. Because rate increase considerably realistic experiments, defects kinetically trapped. In this kinetic stage, from sp(3)-carbon or sp(2)-carbon exhibit marked differences.