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Line stress of step edges at crystal surfaces

Li, W. N. and Duan, H. L. and Albe, K. and Weissmueller, J. (2011):
Line stress of step edges at crystal surfaces.
In: Surface Science, Elsevier Science Publishing Company, pp. 947-957, 605, (9-10), [Online-Edition: http://www.sciencedirect.com/science/article/pii/S0039602811...],
[Article]

Abstract

Step edges at crystal surfaces interact elastically with the underlying bulk solid. The resulting attraction or repulsion between neighboring steps is well described by an established dipole model. Here, we focus on the average stress which a step edge generates in the bulk. This quantity represents an excess of surface stress due to the presence of the step. Within the standard dipole description of the stress field of steps, that excess is zero. Yet, atomistic simulation testifies to a significant variation in the apparent surface stress of vicinal surfaces with the number density of steps. We show how a line stress can be defined as an excess in surface stress per line length. The definition is analogous to that of line tension as an excess of surface tension. Even though the step edge may be viewed as a one-dimensional object, we show that the line stress cannot be represented by a vector along the line; it is also not adequately represented by dipole forces. The line stresses give rise to cusps, typically upward, in polar plots of the principal values of the surface stress tensor in the surface orientation domain. We present a continuum model that links the directionality and magnitude of the line stress to the surface stress at the inclined step face. (C) 2011 Elsevier B.V. All rights reserved.

Item Type: Article
Erschienen: 2011
Creators: Li, W. N. and Duan, H. L. and Albe, K. and Weissmueller, J.
Title: Line stress of step edges at crystal surfaces
Language: English
Abstract:

Step edges at crystal surfaces interact elastically with the underlying bulk solid. The resulting attraction or repulsion between neighboring steps is well described by an established dipole model. Here, we focus on the average stress which a step edge generates in the bulk. This quantity represents an excess of surface stress due to the presence of the step. Within the standard dipole description of the stress field of steps, that excess is zero. Yet, atomistic simulation testifies to a significant variation in the apparent surface stress of vicinal surfaces with the number density of steps. We show how a line stress can be defined as an excess in surface stress per line length. The definition is analogous to that of line tension as an excess of surface tension. Even though the step edge may be viewed as a one-dimensional object, we show that the line stress cannot be represented by a vector along the line; it is also not adequately represented by dipole forces. The line stresses give rise to cusps, typically upward, in polar plots of the principal values of the surface stress tensor in the surface orientation domain. We present a continuum model that links the directionality and magnitude of the line stress to the surface stress at the inclined step face. (C) 2011 Elsevier B.V. All rights reserved.

Journal or Publication Title: Surface Science
Volume: 605
Number: 9-10
Publisher: Elsevier Science Publishing Company
Uncontrolled Keywords: Line stress, Vicinal surface, Transverse coupling
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
Date Deposited: 28 Feb 2012 14:48
Official URL: http://www.sciencedirect.com/science/article/pii/S0039602811...
Identification Number: doi:10.1016/j.susc.2011.02.013
Related URLs:
Funders: Support by the following agencies and programs is acknowledged:, Helmholtz-Chinese Scholarship Society fellowship program (W-N Li), Deutsche Forschungsgemeinschaft, Grant WE1424/13 (JW)., National Natural Science Foundation of China under Grants 10872003 and 10932001, Foundation for the Author of National Excellent Doctoral Dissertation of PR China (FANEDD, Grant no. 2007B2),, Research Fund for the New Teacher Program of the State Education Ministry of China (under Grant no. 200800011011) and Scientific Research Foundation for the Returned Overseas Chinese Scholars State Education Ministry of China (HL D).
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