Carbon Nanotubes, Thermo-mechanical and Transport Properties of

Abstract

Glossary Scanning tunneling microscope (STM) A nano-technology instrument capable of imaging the topography of conducting surfaces with atomistic resolution. It can also be used to manipulate individual atoms and molecules, and construct nano-scale structures. Atomic force microscope (AFM) A nano-technology instrument for investigation of material surfaces on atomistic and molecular scales. It can be used to map the topography of non-conducting surfaces, by sensing the inter-atomic forces, and produce three-dimensional images of these surfaces. Spintronics Refers to the field of spin-based electronics rather than charge-based electronics. It will lead to a new type of device that is based on the use of electron spin for transfer and storage of information. Brillouin zone In solid state physics several Brillouin zones can be defined. The first zone is defined as the Wigner-Seitz primitive cell of the reciprocal lattice. The nth Brillouin zone is defined as the set of points that are reached from the origin by crossing (n 1) Bragg planes. Monte Carlo (MC) method In computational modeling, this method provides a probabilistic scheme for solving a variety of problems by employing powerful sampling techniques. In nano-science and condensed matter physics, one application of this method is for computing the minimum energy state of a nano-structure. Stochastic dynamics (SD) method This refers to the computer simulation method wherein the Langevin equation of motion, describing the random behavior of a particle, is solved as opposed to the deterministic MD method in which Newton's equations of motion are solved. Nano-electromechanical systems (NEMS) These are nano-technology based systems that are the smaller versions of the micro-electromechanical systems (MEMS). They are capable of measuring small displacements , sensing minute amount of substances, and performing rotary motions. NEMS can be constructed via either the top-down approach, i. e., via minia-turization of the micro-scale devices, or via the bottom up approach, i. e., by positioning single atoms or molecules so that a complex and functional nano-system is built from below the nano-scale. Ab initio approach This is the first-principles approach to the computation of the properties, especially the electronic-structure properties, of nano-scale systems using quantum-mechanical concepts and methods. In this method, the structure of a molecule, for instance, is obtained purely from a knowledge of its composition by solving the Schrödinger equation. 690 C Carbon Nanotubes, Thermo-mechanical and Transport Properties of Definition of the Subject Carbon nanotubes form the fourth allotrope of crystalline carbon after graphite, diamond, and a variety of caged-like fullerene molecules, and were discovered in the early 1990s. Their mechanical properties make them stronger than steel, and their thermal conductivity is faster than copper. They have very exotic electronic-conduction properties, namely, by changing their geometry, or introducing topological defects into their structure, their electronic conductance can change from metals to semiconductors. They can also be used to store gases and transport fluids. Furthermore, nano-scale robots, machines, and sensors can be constructed from them, and these can be used to deliver drugs to specific locations in the body, or detect individual cancer cells, or be used as molecular filters to separate minute particles from the environment. Carbon nanotubes are referred to as the fabric of nano-technology, and will play a central role in the future development of this technology. Understanding the properties of nanotubes, via computational simulation studies, has been one of the most intensive areas of research in physical sciences during the past 20 years.