Condensed Matter Seminar Series

Intimate Relationship between Structural Deformation and Properties of Carbon Nanotubes and its Functionalized Derivatives; A first-principles study

Taner Yildirim

National Institute of Standards & Technology

Thursday October 30, 1:30 pm, Room 234, Physics Building

Abstract: Carbon nanotubes continue to surprise scientists with their novel properties. Recently, we have discovered many intimate relationships between mechanical, electronic and chemical properties of single walled carbon nanotubes (SWNT), that could be important in nanotechnological applications. Using state-of-the-art first-principles total energy calculations, we show that the mechanical deformation can control the electronic and chemical properties of SWNTs. The energy band gap is shown to be strongly dependent on the curvature and on the magnitude of the applied mechanical deformation, and the semiconducting band gap decreases and eventually vanishes leading to metalization as a result of increasing radial deformation. We also demonstrate that adsorption of foreign atoms on carbon nanotubes and associated properties can be modified continuously and reversibly by radial deformation. Hence, we conclude that not only the band gap but also chemical reactions taking place on the surface of a SWNT can be engineered through various mechanical deformations. In addition, the effect of deformation is found to be significantly different for the zigzag and armchair SWNT's, which may be important in selective functionalization of nanotubes. Finally, we discuss how the tunable electronic and chemical properties of SWNTs via mechanical deformation can ultimately lead to a wide variety of technological applications such as variable metal-insulator junctions, quantum wells, catalysts, synthesis of metal nanowires, etc.