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Research

The research areas of this Laboratory are: fabrication of nanorods/nanowires and thin films, mechanics of nanostructures, and development of simulation methods.

 

Fabrication of Nanorods/Nanowires and Thin Films

The primary objective is to reveal the scientific principles that govern the fabrication of nanorods or nanowires. A theoretical framework has emerged [see JOM 64, 1253 (2012)] from this effort. Based on the competition of characteristic length scales – such as separation of nanorods [see Applied Physics Letters 100, 141605 (2012)] and the diameter of nanorods [see Physical Review Letters 110,136102 (2013)] – the smallest metallic nanorods using physical vapor deposition are realizable and have been realized.

Mechanics of Nanostructures

The primary objective is to provide atomistic-level physical insights to the mechanics of nanostructures. In terms of elasticity, a nanostructure can be elastically softer or stiffer than its bulk counterpart depending on the competition of bond loss on surfaces, bond saturation on surfaces, reconstruction on surfaces, and nonlinear elasticity under the surfaces. In terms of plasticity, a nanowire can be strengthened by the introduction of twin boundaries. We have demonstrated such introduction by using the combination of electron radiation and mechanical torsion.

Development of Simulation Methods

The objective is to provide methods that optimize physical rigor and computational efficiency. The recently developed Response Embedded Atom Method (R-EAM) allows the rigorous description of crystalline elasticity and surfaces, with very modest increase of computational cost, by a factor of 1.2-1.5 [see Physical Review B 87, 45431 (2013)]. Another simulation method – the polycrystalline lattice kinetic Monte Carlo method – allows the simulation of polycrystalline structure formation and evolution, at the atomic level, in three-dimensional space, and in real time [see Journal of Applied Physics 84, 3636 (1998)Texture Evolution during Thin Film Deposition, in Handbook of Materials Modeling, Springer Science and Business Media, 2005].