Systematic investigation of the growth mechanisms for conventional, doped and bamboo-shaped nanotubes

Fundamental physico-chemical mechanisms underlying the synthesis of nanotubes wereinvestigated, including conventional, doped, and bamboo-shaped nanotubes. The mechanisms are examined from the viewpoint of the well-known base growth (root growth) and tip growth mechanisms. The analysis of the surface characteristics of nanoparticles is key to the present approach. Surface and interface melting, surface and bulk diffusion through nanoparticle, and the formation of a hill due to over-segregation of the source species to the nanoparticle peripheral surface have also been investigated. The study may have led to an understanding of the basics and the differences between the base growth and the tip growths of nanotubes, and also of the formation of nanotube diaphragms (caps), if any. The proposed mechanisms have been used to attempt to explain various prior observations on the conventional, doped, and bamboo-shaped nanotubes. Experimental results available in the literature have been extensively employed to justify the validity of the mechanisms, and to highlight the possible appeal of these mechanisms.