Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 15: Interfaces I
MM 15.3: Vortrag
Montag, 22. März 2010, 15:15–15:30, H5
Line stress of step edges — •weina li1,2, huiling duan2, and jörg weissmüller1,3 — 1Karlsruher Institut für Technologie, Institut für Nanotechnologie, Karlsruhe, Germany — 2Peking University, Beijing, P.R.China — 3Universität des Saarlandes, Saarbrücken, Germany
It is well known that the surface of a solid interact with the underlying volume phase by a mechanical force, which is quantified by the surface stress. By analogy, the line elements at solid surfaces, such as triple lines, edges, or steps may also interact mechanically with the bulk. The forces originating from lines may be derived by taking the derivative of the line tension - an excess in energy per line length - with respect to the strain. The resulting ’line stress’, t, has not been systematically investigated so far. Consider of dimensionality, line stress should be represented by a scalar describing the magnitude of a stress directed along the line. However, it’s well known that parallel step edges at planar surfaces interact via stress fields in the substrate that are dominated by normal stress components. The standard (dipole-) models [1] of step stress predict that line stress is zero. We present molecular statics computations of vicinal surfaces that show a nonzero value, with parallel and normal components. We also present a continuum model which explains the observations in terms of the extra surface stress at the inclined (up- or down-) face of the step edge. The assistance by Karsten Albe in setting up the numerical simulation is greatly acknowledged.
[1] P. Müller, A. Saul, Sur. Sci. Rep 54 (2004), 157.