Nano Science and Technology InstituteNano Science and Technology Institute
Nano Science and Technology Institute 2005 NSTI Nanotechnology Conference & Trade Show
Nanotech 2005
Bio Nano 2005
Business & Investment
Nano Impact Workshop
Program
Sessions
Sunday
Monday
Tuesday
Wednesday
Thursday
Index of Authors
Index of Keywords
Keynote Presentations
Confirmed Speakers
Participating Companies
Industry Focus Sessions
Nanotech Expo
Special Symposia
Conferences
Sponsors
Exhibitors
Venue 2005
Organization
Press Room
Subscribe
Site Map
 
Nanotech 2005 At A Glance
Nanotech Proceedings
Nanotechnology Proceedings
Global Partner
nano tech
Supporting Organizations
Nanotech 2005 Supporting Organization
Media Sponsors
Nanotech 2005 Medias Sponsors
Event Contact
696 San Ramon Valley Blvd., Ste. 423
Danville, CA 94526
Ph: (925) 353-5004
Fx: (925) 886-8461
E-mail:
 
 

Strain and Structure in Nanocrystals

Y. Bae and R.E. Caflisch
University of California, Los Angeles, US

Keywords:
nanocrystals, strain energy, quantum yield and linear elasticity

Abstract:
Layered nanocrystals consist of a core of one material surrounded by a shell of a second material. Because of the small size of these systems, their atomic structure is epitaxial in many cases. Lattice mismatch between the materials in the core and shell leads to elastic strain in a layered nanocrystal. Quantum yield for a layered nanocrystal has been found to correlate with strain. We present computation of the atomistic strain energy density in a layered nanocrystal, using an idealized model with a simple cubic lattice and harmonic interatomic potentials. The present study employs a simple model for the structure and strain of layered nanocrystal. Simulation of this model for a range of geometric and elastic parameters shows that there is a critical shell size at which strain has maximal influence. Moreover, this critical shell size correlated well with the shell size at which quantum yield is maximal. Our main results are as follows. We find that the elastic energy density of nanocrystals is concentrated in the region of the shell, along the interface with the core. Moreover, Figure ef(fig:3D_energy_density} shows that the energy density is more concentrated for thicker shells and the largest values of the energy density are close to the diagonal. Figure ef(fig:max_shell} (a) shows that the maximum energy density as a function of shell thickness peaks with small shell thickness. We define this shell thickness as critical shell thickness $r_s^(*}$ and compare these results to known QY results from expeiments in cite(Uri_critical}. Figure ef(fig:max_shell} (b) shows that the critical shell thickness is the same as that of quantum yield . The robustness of these results with respect to variation of dimension, geometry and material parameters suggests that these results are qualitative and generally applicable. Therefore, our atomistic elastic model has allowed us to investigate the instabilities of nanocrystals which result in their irregular growth with large lattice mismatch.

Back to Program

Sessions Sunday Monday Tuesday Wednesday Thursday Authors

Nanotech 2005 Conference Program Abstract

 
Gold Sponsors
Nanotech Gold Sponsors
Silver Sponsors
Nanotech Silver Sponsors
Gold Key Sponsors
Nanotech Gold Key Sponsors
Nanotech Ventures Sponsors
Nanotech Ventures Sponsors
Sponsors
Nanotech Sponsors
News Headlines
NSTI Online Community
 
 

© Nano Science and Technology Institute, all rights reserved.
Terms of use | Privacy policy | Contact