Convection assisted synthesis of single-walled carbon nanotubes by the electric arc technique

In this thesis, we explored for the first time production of single walled carbon nanotubes (SWCNTs) using the electric arc technique in vertical configuration. The study included growth and characterization of SWCNTs, measurements of key process parameters such as temperature and velocity, and numerical simulations using the commercial code NEKTON. This was the first study of the electric-arc process in vertical configuration, which appears to be superior to the presently used horizontal process.; We obtained the following key results: A deposit, not observed in previous studies (conducted only in the horizontal configuration) grew on the sides of the cathode. We named this deposit “Cathode Texture”.; Our “Cathode Texture” contains primarily thin single-wall nanotubes, having an average diameter ∼0.8 nm. The horizontal configuration always yields 1.4 nm nanotubes.; Bundles of 0.4 nm nanotubes have been obtained for the first time. We determined by thermocouple measurements that “Cathode Texture” with 0.8 nm SWCNTs grew at a relatively cold cathode side wall at about 900 C. ∼1.4 nm SWCNTs grow at ∼1150 C. The spontaneous lifetime of the electronic direct band gap transitions in SWCNTs have been estimated in the order of milliseconds.; Strong unsteady and asymmetric convection was demonstrated in the process chamber. The convection is driven primarily by the hot jet, produced in the arc. This jet enters the process chamber at 13 cm/s. The resulting flow velocity in the process chamber is 5 to 10 cm/s.; Measurements of the temperature and velocity fields during the electric arc process were determined for the first time. The velocity field in the process chamber is complex, unsteady and asymmetric.; A simple model of the electric arc process was developed. The temperature in the electrodes field obtained by NEKTON simulations agrees with the thermocouple measurements.; The velocity field obtained by NEKTON simulations qualitatively agrees with the typical measured convection velocity in the chamber.