PNNL

Abstract

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. Molecular dynamics simulations at 300 K in vacuum were used to study nanoparticle motion and structural changes during aggregation and coarsening of 3 nm sphalerite (ZnS) particles and atomic diffusion during the subsequent phase transformation. Interaction forces between atoms in different nanoparticles can induce translational and rotational movements of the nanoparticles, driving them to find appropriate locations and orientations for aggregation. Following aggregation, the coarsened particle adopts a near-amorphous structure that transforms rapidly to wurtzite. Atomic diffusion is faster on the surface than in the bulk. Transient episodes of very fast atomic diffusion occur locally on the surface. Diffusion plays significant roles in nanoparticle structural change, aggregation, coarsening, and surface nucleation.