Monitoring structural defects and crystallinity of carbon nanotubes in thin films

Abstract

We report the influence of catalyst formulation and reaction temperature on the formation of carbon nanotube (CNT) thin films by the chemical vapour deposition (CVD) method. Thin films of CNTs were grown on Fe-Mo/Al 2 O 3 -coated silicon wafer by thermal decomposition of methane at different temperatures ranging from 800 to 1000 • C. The electron microscopic investigations, SEM as well as HRTEM, of the as-grown CNT thin films revealed the growth of uniform multi-walled CNTs in abundance. The intensity ratio of D-band to G-band and FWHM of G-band through Raman measurements clearly indicated the dependency of structural defects and crystallinity of CNTs in thin films on the catalyst formulation and CVD growth temperature. The results suggest that thin films of multi-walled CNTs with negligible amount of defects in the nanotube structure and very high crystallinity can be obtained by thermal CVD process at 925 • C.

In Vitro and in Vivo Studies of Novel Poly(d,l-lactic acid), Superhydrophilic Carbon Nanotubes, and Nanohydroxyapatite Scaffolds for Bone Regeneration

“…All of the scaffold groups had a strong absorption band at 1750 cm –1 that corresponds to the carbonyl group (C–O) of the PDLLA . Data show the peak at 960 cm –1 , attributed to phosphate stretch mode, identifying the carbonated nHAp presence, and the absorption band of the phosphate groups are found between 1200 and 1030 cm –1 . − The bands in region of 1300–1650 cm –1 and that at 870 cm –1 are designated to carbonate in the surface. − We can observe that the areas of phosphate and carbonate bands were increased in the control group, which occurred probably due to the smaller diameter of surface pores obtained by the control group. Nanosized pores can also act as sites for starting nucleation and apatite crystals growth…”

Elucidating the effect of heating induced structural change on electrical and thermal property improvement of single wall carbon nanotube

“…2d). The G 0 peak has been reported to not depend on increases in the wall number [31]. Therefore, the G 0 /D ratio indicates the level of defects in the CNT graphitic structure, in which a high crystallinity would result in a high ratio.…”

Field electron emission measurements as a complementary technique to assess carbon nanotube quality

“…Endorsing this proposal, the same exponential relationship can be obtained between ATS at first emission and the FWMH of G Peak, in which S7 presented an FWHM of 84.1 cm À1 and the less defective S1 showed an FWHM of 66.8 cm À1 . 35 Moreover, the inset of Fig. 4 presents an exponential relationship between the smallest b and the I D /I G ratios plotted high to low on the x-axis.…”