(623c) Growth Mechanism of Five-Fold Twinned Ag Nanowires from Multi-Scale Theory and Simulations

Five-fold twinned nanowires can be synthesized from various fcc metals via solution-phase methods. These anisotropic nanostructures can be grown with aspect ratios (AR) beyond 1000 and they possess unique electrical, optical, and mechanical properties that show promise for many applications. Despite considerable interest in their synthesis and properties, the kinetic mechanisms that promote the high-AR growth of metal NW are not well understood. We combine atomic-scale, meso-scale, and continuum theoretical methods to predict growth morphologies of Ag nanowires from seeds and to demonstrate that high aspect-ratio nanowires can originate from anisotropic surface diffusion induced by the strained nanowire structure. Nanowire seeds are similar to Marks decahedra, with {111} “notches” that accelerate diffusion along the nanowire axis to facilitate one-dimensional growth. The strain distribution on the {111} facets induces heterogeneous atom aggregation and leads to atom trapping at the nanowire ends. We predict that decahedral Ag seeds can grow to become nanowires with aspect ratios in the experimental range. Our studies show that there is a complex interplay between atom deposition, diffusion, seed architecture, and nanowire aspect ratio that could be manipulated experimentally to achieve controlled nanowire syntheses.