Curvature dependence of electric and thermal conductivity in carbon nanotubes
This presentation is the property of its rightful owner.
Sponsored Links
1 / 11

Curvature dependence of electric and thermal conductivity in carbon nanotubes PowerPoint PPT Presentation


  • 85 Views
  • Uploaded on
  • Presentation posted in: General

Curvature dependence of electric and thermal conductivity in carbon nanotubes. Wan-Ju Li Phys 570X Proposal presentation 04/22/2009. Outline. Motivation Introduction Conductivities under strain Summary. Motivation.

Download Presentation

Curvature dependence of electric and thermal conductivity in carbon nanotubes

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Curvature dependence of electric and thermal conductivity in carbon nanotubes

Wan-Ju Li

Phys 570X Proposal presentation

04/22/2009


Outline

  • Motivation

  • Introduction

  • Conductivities under strain

  • Summary


Motivation

  • Structure deformations are common in the growth of CNTs as well as in developing CNT-based nano devices.

  • Dependences of electric and thermal conductivities on the radius of the CNTs and the curvature radius are essential for estimating the preperties of our designed nano device.


Introduction-electric conductivity

M: number of transport channels

G: electric conductance

E: energy of electrons

When E lies inside a band gap we can use quantum mechanical penetration or thermal activation transport to obtain the transmission coefficient and then get electric conductance.

J X Cao, X H Yan, J W Ding and D L Wang, J. Phys.: Condens. Matter 13 (2001) L271–L275


Introduction-electric(cont.)

Liu Yang and Jie Han,

Phys.Rev.Lett. 5,154(2000)

E. D. Minot,et al (McEuen group) Phys.Rev.Lett.90.156401(2003)


Introduction-Molecule Dynamics

  • Computer Simulation

  • Interatomic potential form

  • Newtonian dynamics

Example of a molecular dynamics simulation in a simple system: deposition of a single Cu atom on a Cu (001) surface. Each circle illustrates the position of a single atom;

http://en.wikipedia.org/wiki/Molecular_dynamics


Introduction-Molecule Dynamics

Potential form for our problem

Parameters, except R and D, are chosen to fit the cohesive energy, lattice constant, and bulk modulus of diamond. For carbon we choose R=1.95A D=0.15A, where R is chosen to include only the first neighbor shell.

J. Tersoff, PRB 37, 6991(1988)


Introduction-thermal conductivity

Thermal conductivity λ is related to the thermal current correlation function.

Savas Berber, Young-Kyun Kwon,* and David Tománek, Phys.Rev.Lett.84,4613(2000)


r

R

Electric conductivity under strain

  • Tight binding model for band structure

  • Add band gap modification

  • Get electric conductance (conductivity) as a function of incident energy

  • Also include effects of tube radius and curvature radius


r

R

Thermal conductivity under strain

  • Specify the geometry under strain

  • Molecule Dynamics simulation

Michael C H Wu and Jang-Yu Hsu,

nanotechnology 20 145401(2009)


Summary

  • In order to predict the behaviors of designed nano devices it is necessary to understand the influence of curvature

  • Electric conductivity-

    Tight-binding model

    + change of gap by strain

  • Thermal conductivity-

    Molecule dynamics simulation

R. Heyd. et al, PRB 55,6820(1997)


  • Login