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Title: Stress in titania nanoparticles: An atomistic study

Stress engineering is becoming an increasingly important method for controlling electronic, optical, and magnetic properties of nanostructures, although the concept of stress is poorly defined at the nanoscale. We outline a methodology for computing bulk and surface stress in nanoparticles using atomistic simulation. The method is applicable to ionic and non- ionic materials alike and may be extended to other nanostructures. We apply it to spherical anatase nanoparticles ranging from 2 to 6 nm in diameter and obtain a surface stress of 0.89 N/m, in agreement with experimental measurements. Based on the extent that stress inhomogeneities at the surface are transmitted into the bulk, two characteristic length-scales are identified: below 3 nm bulk and surface regions cannot be defined and the available analytic theories for stress are not applicable, and above about 5 nm the stress becomes well-described by the theoretical Young-Laplace equation. The effect of a net surface charge on the bulk stress is also investigated. It is found that moderate surface charges can induce significant bulk stresses, on the order of 100 MPa, in nanoparticles within this size range.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
1132192
Report Number(s):
PNNL-SA-98377
KC0203020
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Chemistry Chemical Physics. PCCP, 16(20):9441-9447
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
molecular dynamics simulations; titania nanoparticles; stress