Nanotube growth rate

Cation was found to be the key parameter influencing both the nanotube growth rate and length [49], With increasing cation size, the interfacial oxide layer was getting thinner. Ionic transport was facilitated and the nanotube growth was enhanced. The thinnest nanotubes ever reported was 5 nm, which was obtained in an electrolyte containing 0.5 M tetrabutylammonium fluoride in formamide with 5% water (Fig. 8). 

Kpetsu JBA, Jedrzejowski P, Cote C, Sarkissian A, Merel P, Laou P, et al. Influence of Ni catalyst layer and TiN diffusion barrier on carbon nanotube growth rate. Nanoscale Res Lett 2010 5 539. ... 

The discussed models of the carbon nanofilaments and nanotubes forma tion allow many other thermodynamic factors to be taken into consider ation, all of which affect the shape, texture, and growth rate of the nano objects under discussion (see, e.g.. Refs. [6, 7]). It is assumed that the forma tion of the fluidized active component of the catalyst nanoparticles due to its stationary oversaturation with the crystallizing component gives rise to the possibility to synthesize nanofilaments and nanotubes from not only carbon but also from different substances, such as silicon carbide (over catalysts capable of dissolving carbon and silicon simultaneously), germanium metal (over gold metal catalysts [8]), and so on. 

The method is apt to produce structured nanotube films as required, for example, for field emission displays. To this purpose the catalyst is lithographed onto the substrate. The high growth rate then leads to sharply contoured structures of... 

Figure 3.18 Nanotube arrays generated by CVD with added water, (a) The high growth rates enable the production of macroscopic amounts within just a few minutes, (b) Various...

Vapor-phase techniques are not as widely used as growth from the melt or solution because the growth rate is generally slow or only small crystals can be grown. However, two vapor-phase techniques have commercial application the growth of whiskers or small islands (e.g., SiC and GaN) by the VLS process and the growth of SiC and nanotubes by sublimation processes. 

The rate of nanotube growth can be increased by bigb-intensity ultrasonication during the anodization process [8]. Under ultrasonication, the transient curve (current density plotted vs. anodization time) is modified probably due to more rapid dissolution of the titanium foil. 

Figure 5.9 shows the growth rate (R) as a function of reciprocal (absolnte) temperature for various PE-CVD and T-CVD synthesized nanotubes, nanoflbers, and graphene [135,192,204]. Data has been linearly fitted according to the Arhenius relation ... 

Kim KE, Kim KJ, Jung WS, Bae SY, Park J, Choi J, et al. Investigation on the temperature-dependent growth rate of carbon nanotubes using chemical vapor deposition of ferrocene and acetylene. Chem Phys Lett 2005 401 459-64. 

In principle, carbon nanotubes can be grown from any gaseous hydrocarbons or CO, onto Fe, Co, or Ni particles dispersed on a substrate under appropriate reaction conditions. Higher temperatures and slower growth rates favor graphitic filament formation, while lower temperatures and fast rates lead to nongraphitic forms (Baker and Harris, 1978). Beside Fe, Co, and Ni, filaments can also be formed on other metals such as Pt and Cu. Acetylene is among the most reactive hydrocarbon precursors. Unsaturated hydrocarbons like propylene and butadiene are more reactive than the saturated hydrocarbons such as methane and... 

One particularly interesting, and likewise promising, market with unprecedented growth rates appears to exist for carbon nanotubes (CNTs), the global demand for which in electronic, automotive and aerospace and defense applications is summarized in Table 6.7. 

Choi YC, Shin YM, Lee YH, Lee BS, Park GS, Lee NS, et al. Controlling the diameter, growth rate, and density of vertically aUgned carbon nanotubes synthesized by microwave plasma-enhanced chemical vapor deposition. Appl Phys Lett 2000 76 2367-9. 

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