Diffusion Growth Mechanism of Five-Fold Twinned Ag Nanowire

Five-fold twinned nanowires can be produced with high aspect ratios from diverse face-centered cubic (fcc) metals. However, the mechanism of their anisotropic growth is still poorly understood. We develop a model combining deposition and surface diffusion to predict the diameters and the aspect ratios of Ag nanowires. We describe two aspects of nanowire growth, denoted as the seed process and the wire process. In the seed process, the deposition time is much longer than the surface diffusion time, so that the seed shape only depends on the difference between interfacet diffusion times. The structure of nanowire seeds is similar to Marks decahedra with {111} notches and {110} steps that accelerate interfacet diffusion leading to wire growth. The result exhibits that the decahedron seeds could lead to three kinds of products with different strucutures as nanowires, decahedron particles and giant decahedron seeds. We focus on the seeds growing to nanowires and introduce the wire process, which occurs subsequently and continues until the diffusion time is equal to the deposition time. We predict the aspect ratio by contrasting the diffusion rate from {100} to {111} to the deposition rate on {100}. The aspect ratios predicted in our simulations are in the experimental range.