The generation of domain boundaries in catalytically-grown carbon nanotubes

Arrays of catalytically-grown multi-wall carbon nanotubes were grown using identical conditions in a chemical vapor deposition environment, but cooled at different cooling rates, to identify the influence of cooling rate on the structural properties of the nanotube at the catalyst-wall interface. Ex-situ transmission electron microscopy led to the identification of twist, twin, and tilt domain boundaries in all samples irrespective of cooling rate. In addition, the relative position of twist, twin, and tilt domain boundaries in nanotubes cooled at different rates was maintained uniformly across all samples cooled at different rates. The results are interpreted in light of the concurrence of base- and tip-growth for the catalytic synthesis of nanotubes, suggesting a rather steady position occupied by the domain boundaries coupled to the catalytic particles.