Effect of nanoparticle density on narrow diameter distribution of carbon nanotubes and particle evolution during chemical vapor deposition growth

Jeong, Goo‐Hwan; Suzuki, Satoru; Kobayashi, Yoshihiro; Yamazaki, Akira; Yoshimura, Hideyuki; Homma, Yoshikazu

doi:10.1063/1.2146054

Cited by 51 publications

(43 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, if the length and width distributions have a positive correlation, then the consequences of such a length distribution are completely different. To estimate the level of correlation, one could argue that the probability of breaking SWCNTs also exhibit a diameter variation 39,50 and for these the scission energy, which is proportional to the number of bonds that have to be broken, presumably scales linearly with the diameter. If D γ = αL i , we find that…”

Section: Realistic Size Distributionsmentioning

confidence: 99%

Connectivity percolation of polydisperse anisotropic nanofillers

Otten¹,

Schoot²

2011

The Journal of Chemical Physics

127

168

View full text Add to dashboard Cite

We present a generalized connectedness percolation theory reduced to a compact form for a large class of anisotropic particle mixtures with variable degrees of connectivity. Even though allowing for an infinite number of components, we derive a compact yet exact expression for the mean cluster size of connected particles. We apply our theory to rodlike particles taken as a model for carbon nanotubes and find that the percolation threshold is sensitive to polydispersity in length, diameter, and the level of connectivity, which may explain large variations in the experimental values for the electrical percolation threshold in carbon-nanotube composites. The calculated connectedness percolation threshold depends only on a few moments of the full distribution function. If the distribution function factorizes, then the percolation threshold is raised by the presence of thicker rods, whereas it is lowered by any length polydispersity relative to the one with the same average length and diameter. We show that for a given average length, a length distribution that is strongly skewed to shorter lengths produces the lowest threshold relative to the equivalent monodisperse one. However, if the lengths and diameters of the particles are linearly correlated, polydispersity raises the percolation threshold and more so for a more skewed distribution toward smaller lengths. The effect of connectivity polydispersity is studied by considering nonadditive mixtures of conductive and insulating particles, and we present tentative predictions for the percolation threshold of graphene sheets modeled as perfectly rigid, disklike particles.

show abstract

Section: Realistic Size Distributionsmentioning

confidence: 99%

Connectivity percolation of polydisperse anisotropic nanofillers

Otten¹,

Schoot²

2011

The Journal of Chemical Physics

127

168

View full text Add to dashboard Cite

show abstract

“…The size of catalyst nanoparticles can be increased by the continued agglomeration of small catalyst particles during the CVD process or the enhanced diffusion along the growing nanotube surface [29]. Simultaneously, the dissolution of carbon atoms in the particles and the formation of amorphous carbon or a graphitic carbon shell from excessive carbon species covering on the Co nanoparticle surface could also give rise to the increase of nanoparticle size [24,27,30].…”

Section: Resultsmentioning

confidence: 99%

“…1(a)] which constantly affect the stability of the AFM tips, it was not possible to resolve the SWNTs unambiguously and confirm a clear particle-tube relationship of the silica sample by AFM. However, based on the fact that, the catalytic nanoparticle size gives the upper bound for the nanotube diameter [24,27,29], we could expect here that, base on the Co nanoparticle size distribution, the diameters of SWNTs on our thermal SiO 2 surface should show slightly smaller diameter than that on quartz.…”

Section: Resultsmentioning

confidence: 99%

A Comparative Study of Cobalt Catalyst Behavior between Silica and Quartz Substrates for Single-Walled Carbon Nanotube Growth

Xie

Inaba

Yamada

et al. 2011

e-J. Surf. Sci. Nanotechnol.

Self Cite

View full text Add to dashboard Cite

The cobalt (Co) catalyst behavior for SWNT growth on thermal oxidized silica and single-crystalline quartz by using alcohol chemical vapor deposition (CVD) was compared. The influence of the nature of substrate surface was analyzed from the size and density of both catalyst nanoparticles and SWNTs. The Co nanoparticles, on the quartz substrate after growth, had a mean diameter of about 5.9 nm which was larger than that (2.1 nm) on the silica substrate. Randomly dispersed SWNTs with a higher density were obtained on silica, while aligned SWNTs with a lower density were achieved on ST-cut quartz. The lower density of the nanoparticles on the quartz substrate can be attributed to a larger surface diffusion length of Co atoms in comparison with the silica surface.

show abstract

“…There appears to be a consensus in the literature concerning the correlation of catalyst size and SWNT diameter. Several groups have observed a direct dependence of the two quantities (Jeong et al, 2005;Wei et al, 2001). However, whether there is a correlation between the atomic structure/facets of the nanoparticle catalyst and the chirality of the synthesized nanotube has not yet been determined.…”

Section: Discussionmentioning

confidence: 99%