Growth mechanisms of carbon nanotubes converted from diamond-like carbon films

Trying to understand the growth mechanism of the carbon nanotubes (CNTs), a very simple growth approach was undertaken. Nanotubular structures were grown from diamond-like carbon (DLC) films. Vacuum annealing of DLC (C-sp3 rich) films mixed with catalysts in argon atmosphere at 1000 °C leads to the formation of the nanotubular structures. In the same growth process graphite (100% C-sp2) does not promote to form CNTs. We proposed the growth mechanism in two step process: (1) conversion of C-sp3 phase into C-sp2 phase in the presence of the catalyst(s) at elevated temperature; (2) crystallization and rolling of C-sp2 in tubular shape.