Coalescence-induced shape transformations in Pd and AuPd clusters

The coalescence of pure Pd and Pd-rich AuPd nanoparticles is studied by molecular dynamics simulations. The collision of icosahedral nanoparticles with face-centered-cubic truncated octahedral ones is considered. These structures are considered because they have been experimentally shown to be the most stable for AuPd nanoalloys and for pure Pd clusters. The final structures of the coalescence process are determined depending on the composition of the initial colliding units, which heavily influences the structure of the final outcome. The key mechanisms at the atomic level of coalescence processes are analysed, revealing the peculiar types of collective atomic rearrangements that enable the transformation of an icosahedron into a sequence of close packed planes and, conversely, the transformation of a series of close packed planes into icosahedral shells.