The influence of activation and growth time on the geometry and structural perfection of multi-walled carbon nanotubes

We studied the influence of the activation time on the phase composition and geometric parameters of catalytic centers (CC). We found, that the treatment of substrate in an ammonia atmosphere allows to restore oxidized nickel. The activation time and the presence of ammonia plasma do not affect the phase composition of catalyst, but has a significant effect on the geometric dimensions of catalytic centers. Also we studied the influence of growth time on the geometry and structure of vertically aligned carbon nanotubes (VACNT). When the growth time ranged from 5 to 15 min we observed the formation of new walls, which resulted in an increase of the outer diameter. Within the range of 15 to 30 minutes, however, there was a decrease in the diameter of carbon nanotubes, which is associated with the disturbance of structural perfection and disorientation of carbon nanotubes caused by wall undercutting in the plasma. (paper)