Article

# Mechanical Properties of Silicon Nanowires.

Nanoscale Research Letters (Impact Factor: 2.48). 01/2009; 5(1):211-216. DOI: 10.1007/s11671-009-9467-7

Source: PubMed

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**ABSTRACT:**The plastic response of perfect face-centred cubic single-crystal aluminium (Al) nanowires (NWs) under torsion is studied using molecular dynamics simulations. The Al–Al interaction is described by the many-body tight-binding potential. The effects of the crystal orientation and aspect ratio of the NWs on their deformation are evaluated in terms of atomic trajectories, potential energy, a centrosymmetry parameter and the torque required for deformation. Simulation results clearly show that for NWs, regardless of crystal orientation, dislocations nucleate and propagate on the (1 1 1) close-packed plane. In a NW under torsion, dislocations begin at the surface, extend to the interior along the (1 1 1) close-packed plane and finally diffuse to the middle part. A 〈1 1 0〉-oriented NW has the lowest required torque for deformation due to the occurrence of homogeneous deformation. The mechanism of the plastic response of an Al NW depends on its crystal orientation. For a long NW, geometry instability occurs before material instability (buckling).Molecular Simulation 06/2013; 39(7). · 1.12 Impact Factor -
##### Article: a Finite Element Study of Diffusion-Induced Mechanics in Li-Ion Battery Electrode Materials

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**ABSTRACT:**In this paper, a Finite Element (FE) framework for studying diffusion induced mechanics of Li-ion battery electrode materials is presented. In a previous study [Vanimisetti and Ramakrishnan (2011), Proc. IMechE, Part C: J. Mech. Eng. Sci. 0954406211432668], a set of analytical expressions for the stress distribution in ideal geometries, such as slab and cylindrical shaped particles, were derived using thermal stress analogy while solutions for spherical particles already exist. However, the limitations of the analytical study in handling complex geometries, the material behavior and the functional parameters necessitated the development of an FE model based approach. A multi-physics model was developed in COMSOL® package linking diffusion phenomenon to stress development. The model was verified comparing the results with those of the earlier analytical studies. As an illustration, we use the model to make inferences with regard to the effect of electrode particle shape. Along similar lines, the diffusion-induced mechanics in silicon rod structures grown on copper current collector is also demonstrated.International Journal of Computational Materials ScieInternational Journal of Computational Materials Science and Engineeringnce and Engineering 09/2012; 1(3):50028-. - [Show abstract] [Hide abstract]

**ABSTRACT:**In this work, we have modeled a three point bending test of monocrystalline Si nanowires using molecular dynamics simulations in order to investigate their elastic properties. Tested nanowires were about 30 nm in length and had diameters from 5 to 9 nm. To study the influence of a native oxide layer, nanowires were covered with a 1 nm thick silica layer. The bending force was applied by a carbon diamond half-sphere with a 5 nm diameter. The Si-O parametrization for the Tersoff potential was used to describe atomic interactions between Si and O atoms. In order to remove the indentation effect of the diamond half-sphere and to obtain a pure bending behavior, we have also performed a set of simulations with fixed bottoms of the nanowires. Our results show that the oxide layer reduces the nanowire stiffness when compared with a pure Si nanowire with the same number of silicon atoms—in spite of the fact that the oxidized nanowires had larger diameters.Journal of Applied Physics 03/2014; 115(10):104305-104305-5. · 2.19 Impact Factor

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