Tailoring the formation of textured oxide films via primary and secondary nucleation of oxide islands

Abstract Complex hierarchical architectures of nano/microcrystals are of great interests for tuning material properties at the micro- and meso-scale. Unfortunately, the fundamental mechanisms underlying the hierarchical organization of nanocrystals, especially the preferred crystallographic directions and their inter-transitions, remain largely elusive. Herein, we demonstrate the tunability of the crystallographic orientations in textured oxide films through a two-stage nucleation process of oxide nanoislands in metal oxidation. Using in situ environmental transmission electron microscopy, we manipulate the oxidation of copper to result in a dually-structured architecture of Cu2O nanocrystalline films via primary nucleation of cube-on-cube epitaxy of oxide islands, and secondary nucleation of oxide islands on side facets of the primary islands. This dual-nucleation mechanism of oxide islands may find broader applicability in making hierarchical architectures of other nanocrystalline metal oxides.