(Invited) Synthesis of Monochiral CNTs

The conductivity of CNT yarn or wire depends on chirality, alignment, doping, lack of contamination, residual amorphous carbon, and twist angle. All these factors must be well controlled to obtain good conductivity. This talk addresses one of these issues, the synthesis of all metallic tubes, and as it happens these tend to be of predominately the same chirality. The synthesis and characterization of monochiral tubes are difficult due to variable bundle strain and the consequent shift in the Radial Breathing Mode Peaks. In this presentation, we present a method for compensating for this strain phenomenon that utilizes the known strain-free position of the G band. We also present TEM data of SWCNT metallic carbon nanotube material as is, and with amorphous carbon removed. The latter is important to analytically determine the crystal structure and diameter of the tubes. We found that: (1) the tubes are remarkably consistent in diameter, (2) the diameters ranged from about 1.2 to 2.5 nm but most bundles were about 1.7nm consistent with our TEM and Raman findings, and finally (3) We found that all the tubes resided in bundles that vary in size. We used both acetylacetonate and benzyl alcohol as carbon sources. We showed by TEM the bundles are monochiral.