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Figure 1: Methods for computing Young’s modulus and the thermal expansion coefficient:
(a) Young’s modulus is computed by obtaining the strain energy as a function of longitudinal strain. The cross-sectional view of a typical Core-Shell NanoWire (CSNW) is also shown.
(b) The thermal expansion is obtained from the thermal strain in a direct MD simulation. At higher temperatures, the thermal fluctuations increase, thereby causing the MD data to be dispersed more broadly. The plots presented here correspond to a Si/Ge, <111> CSNW with a 4 nm core diameter.
FROM:
Suvankar Das, Amitava Moitra, Mishreyee Bhattacharya and Amlan Dutta (primarily from S. N. Bose National Centre for Basic Sciences, Sector - III, Salt Lake, Kolkata 700098, India),
“Simulation of thermal stress and buckling instability in Si/Ge and Ge/Si core/shell nanowires”, Beilstein Journal of Nanotechnology, Vol. 6, pp 1970-1977, 2015, doi:10.3762/bjnano.6.201
ABSTRACT: The present study employs the method of atomistic simulation to estimate the thermal stress experienced by Si/Ge and Ge/Si, ultrathin, core/shell nanowires with fixed ends. The underlying technique involves the computation of Young’s modulus and the linear coefficient of thermal expansion through separate simulations. These two material parameters are combined to obtain the thermal stress on the nanowires. In addition, the thermally induced stress is perceived in the context of buckling instability. The analysis provides a trade-off between the geometrical and operational parameters of the nanostructures. The proposed methodology can be extended to other materials and structures and helps with the prediction of the conditions under which a nanowire-based device might possibly fail due to elastic instability.
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