Multiwall carbon nanotubes: Self-organization and inhibition of step-flow growth kinetics

Citation
Oa. Louchev et al., Multiwall carbon nanotubes: Self-organization and inhibition of step-flow growth kinetics, J APPL PHYS, 89(6), 2001, pp. 3438-3446
Citations number
61
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF APPLIED PHYSICS
ISSN journal
0021-8979 → ACNP
Volume
89
Issue
6
Year of publication
2001
Pages
3438 - 3446
Database
ISI
SICI code
0021-8979(20010315)89:6<3438:MCNSAI>2.0.ZU;2-R
Abstract
In this article the results of a numerical study on the self-organization a nd inhibition of step-flow growth of carbon nanotubes viewed within the fra mework of the continuum surface diffusion equation are given. Incorporation constants of C atoms, which differ depending on what side of the step the atom has been chemisorbed prior to incorporation, are considered. These dif ferences can lead to the onset of surface multi-island nucleation in front of a propagating step with decrease in the growth temperature. This effect is able to cause formation of defects in the growing layer and even to inhi bit stable step-flow modes of nanotube growth, leading to the formation of misoriented surface nuclei which may be likened to amorphous matter. A diag ram distinguishing three characteristic temperature regions for nanotube fo rmation is given: (i) the region where there is no secondary layer nucleati on because the surface concentration of adsorbate on the surface of the fir st layer is not sufficiently high, (ii) the region of successive nucleation and propagation of one layer after another, i.e., stable step-flow growth, and (iii) the region where the nanotube surface is prone to multi-island n ucleation, which inhibits stable step-flow growth and causes "amorphization " of the external surface of the nanotube. The simultaneous propagation of multilayer steps coupled by lip-lip interaction is shown to be feasible onl y if a microkinetic mechanism exists, which effectively redistributes to th e edges of internal layers the atoms arriving initially by surface diffusio n at the edge of the external layer (C) 2001 American Institute of Physics.