No abstract

The unpredictability of different operational parameters has rendered finding the optimum conditions for carbon nanotube (CNT) growth particularly challenging. This study attempts to explore the effect of temperature and pressure based on the growth regimes suggested by Lebedeva et al. (Carbon 2011, 49, 2508−2521. While the absorption regime resulted in premature growth, the surface-and diffusion-controlled ones showed a remarkable growth of carbon products. Along with these two regimes, the diameter, array height, and quality of CNTs generally increased with an increase in temperature, but these parameters experienced a reduction near the boundary between two regimes. Just before this reduction, the location may be considered as the optimum condition for growing tall arrays of high-quality CNTs. The quality and quantity of the grown CNTs improved as the pressure increased up to 7000 Pa.

No abstract

While the effects of partial pressure of carbon feed on the growth of carbon nanotubes (CNTs) are well documented, the effects of total pressure in the growth chamber are not well understood. To shed some light, we investigated the growth of CNTs at different total pressures and a constant partial pressure using catalytic chemical vapour deposition method. It was observed that the growth height and diameter of CNTs decreased as the total pressure increased, probably due to the dilution of carbon feed, the increase in the boundary layer thickness and the decrease in the gas diffusion coefficient. Furthermore, the growth quality of the CNTs was found to be highest at intermediate total pressures. This can provide clues as to where the best temperature concentration is for high-quality CNTs.