Synthesis arc-discharge

Carbon tubules (or nanotubes) are a new form of elemental carbon recently isolated from the soot obtained during the arc-discharge synthesis of fuller-enes[I]. High-resolution electron micrographs do not favor a scroll-like heUcal structure, but rather concentric tubular shells of 2 to 50 layers, with tips closed by curved, cone-shaped, or even polygonal caps. Later work[2] has shown the possibility of obtaining singleshell seamless nanotubes. 

ARC DISCHARGE SYNTHESIS OF METALLOFULLERENES USING A CARBON ELECTRODE WITH CHEMICALLY MODIFIED SURFACE... 

Yet contrary to the arc discharge synthesis of multiwalled nanotubes, the yield of carbon materials is not hmited to the cathode deposit. Actually much larger amounts and concentrations of SWNT are found elsewhere in the reactor. Especially the deposits on the walls of the apparatus are rich in single-waUed tubes. From these locations the precipitate can be peeled off like some textile material (Figure 3.13). Furthermore, there is a kind of collar around the edges of the... 

An article by lijima showed that carbon nanotubes are formed during arc-discharge synthesis of C, and other fullerenes also triggered an outburst of the interest in carbon nanofibers and nanotubes. These nanotubes may be even single walled whereas, low-temperature, catalytically grown... 

Arc-discharge synthesis of CNTs in the presence of several metals has been discussed for filling CNTs [110]. Mainly nano wires were obtained using this procedure and some of them do not completely fill the CNT. 

Arora N, Sharma NN. Arc discharge synthesis of carbon nanotubes comprehensive review. Diamond and Related Materials 2014 50 135-50. http //dx.doi.org/10.1016/ j. diamond.2014.10.001. 

Zhang, Y.-L., Hou, P.-X., Liu, C., Cheng, H.-M., 2014a. De-bundling of single-wall carbon nanotubes induced by an electric field during arc discharge synthesis. Carbon 74, 370—373. 

O Table 19-1 lists the total amount of possible isomers of fidlerenes C for different . These numbers clearly show that consideration of all isomers is hardly feasible for the low-symmetric structures. For instance, 99918 isomers are possible for C90, and the information that an experimentally studied isomer has C2 symmetry allows one to reduce the structural guesses to 1266 isomers, which is stiU not very feasible. On the other hand, the number of isomers formed in arc-discharge synthesis is usually rather low. Therefore, it seems possible and highly desirable to develop some simple rules to reduce the number of isomers that should be considered. 

C82 has seven IPR isomers, but only one of them, 2(3), was isolated in pure form (Kikuchi et al. 1992 Zalibera et al. 2007). 2(3) is the most stable isomer of C82 and has large HOMO-LUMO gap (Sun and Kertesz 2001a), so its high abundance is not surprising. Meanwhile, Cs(4) isomer is also rather stable and has similar gap, but this isomer has never been observed. The studies of the insoluble fullerene fraction have shown that 2(5) isomer is also formed in the arc-discharge synthesis, as verified by the isolation and characterization of its CF3 derivative, (C82-C2(5))(CF3)i2 (Shustova et al. 2006). 

Experimental structural information on the empty fullerenes beyond C92 is very scarce and usually limited to the mixtures of isomers. X-ray crystallographic study of C94(CF3)2o and C96(C2F5)i2 obtained by perfluoroalkylation of the higher fuUerene mixture with subsequent HPLC separation proved formation of C94-C2(61) and G96-Ci(145) isomers in the arc-discharge synthesis (Tamm et al. 2009a), but these data are inconclusive since the actual isomeric composition of the initial fullerene mixture remains unknown. Yet, a lot of calculations were performed for larger fullerenes, and systematic information on the lowest energy isomers is available up to Ciso. 

The mechanical removal of powder from the sample surface (for example from the cathode electrodes after the arc discharge synthesis). 

In the arc discharge synthesis of CNTs, Bethune and co-workers used thin electrodes with hored holes filled with a mixture of pure powdered metals (Fe, Ni, or Co) and graphite as anodes. The electrodes were vaporized with a current of 95-105 A in 100-500 Ton of helium gas. TEM analysis of the obtained samples revealed that only cocatalyzed CNTs had single-atomic-layer walls with uniform diameters of 1.2 0.1 nm (Figure 7). 

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