Direct Atomic Simulations of Facet Formation and Equilibrium Shapes of SiC Nanoparticles

Understanding the shapes of nanoparticles is an important interdisciplinary problem because particle shapes can affect their properties, functionality and applications. Advances in nanoscale imaging probes have revealed exquisite details of nano-faceting phenomena. However, quantitative theoretical predictions have not kept up pace with experimental advances, and the atomic pathways of facet formation are largely unknown due to a lack of direct observations and simulations. Here we examine facet formation in spherical and cubic SiC nanoparticles and in SiC nanowires using molecular dynamics simulations reaching microseconds. We characterize layer-by-layer formation, diffusional motion along edges and corners, and determine energy barriers. We find that the equilibrium shapes are identical regardless of the initial shape of SiC nanoparticles or nanowires. For spherical and cubic nanoparticles, (110) facets form within 10 ns by lateral liquid-like diffusion of atoms. In contrast, faceting in SiC nanowires a...