2 research outputs found
Growth Analysis of Single-Walled Carbon Nanotubes Based on Interatomic Potentials by Molecular Dynamics Simulation
Molecular
dynamics simulation was performed to understand the growth
mechanism of single-walled carbon nanotubes (SWNTs) by using the Brenner–Tersoff
potential as the interaction among carbon atoms (C–C) and the
Tersoff-type potential as the interaction between carbon and metal
(C–M) and between metal and metal atoms (M–M). The potential
functions for C–M and M–M bonds were established from
the results of ab initio calculations. The growth of high-quality
SWNTs was simulated at a suitable temperature and supply ratio of
carbon atoms. The potential energy of carbon atoms was strongly dependent
on the number of C–C and C–M bonds. The dependence explains
the growth process, including cap formation, its lift-off, and the
continuous SWNT growth
Digital Isotope Coding to Trace the Growth Process of Individual Single-Walled Carbon Nanotubes
Single-walled
carbon nanotubes (SWCNTs) are attracting increasing
attention as an ideal material for high-performance electronics through
the preparation of arrays of purely semiconducting SWCNTs. Despite
significant progress in the controlled synthesis of SWCNTs, their
growth mechanism remains unclear due to difficulties in analyzing
the time-resolved growth of individual SWCNTs under practical growth
conditions. Here we present a method for tracing the diverse growth
profiles of individual SWCNTs by embedding digitally coded isotope
labels. Raman mapping showed that, after various incubation times,
SWCNTs elongated monotonically until their abrupt termination. <i>Ex situ</i> analysis offered an opportunity to capture rare
chirality changes along the SWCNTs, which resulted in sudden acceleration/deceleration
of the growth rate. Dependence on growth parameters, such as temperature
and carbon concentration, was also traced along individual SWCNTs,
which could provide clues to chirality control. Systematic growth
studies with a variety of catalysts and conditions, which combine
the presented method with other characterization techniques, will
lead to further understanding and control of chirality, length, and
density of SWCNTs