Ab initio study of carbon nanotube based conductors

Abstract

The development of new high strength, high reliability, and high ampacity conductors can benefit a wide range of commercial and military systems. Improved conductors are needed to perform a variety of power and data transmission functions, and their strategic research importance is highlighted in numerous publications. The most promising opportunities for fundamental improvements in conductors appear to be offered by carbon nanotube (CNT) based composites. Material architectures of interest include doped nanotube wires and cables, and nanotube-copper composites. Although the electrical conductivity of current CNT fibers lag copper by an order of magnitude, a mass specific comparison shows that CNT composites are promising candidates for disruptive advances in conductor technology. The majority of published research on carbon nanocomposite conductors has taken an experimental approach. Although experimental research has been productive, the complexity of the materials design problem motivates complementary efforts on simulation. Simulation can serve as a valuable adjunct to experiment, in particular when published experimental studies speculate on physics which may not be amenable to direct experimental measurement. This thesis investigates the conductance of iodine or chromium doped CNT and copper-CNT nanocomposites using ab initio methods, which can complement experimental work by estimating the performance of systems that may be difficult to study experimentally. Both conductor and junction models of these nanomaterials were built to perform conductance calculations. Based on the computed microscopic properties, a transmission line model is proposed to predict the behavior of nanowires. The results suggest that iodine doped carbon nanotube conductors are viable research and development candidates for electrical conductors in ship and aircraft applications, where mass specific conductivity is of central interest.