Microstructure of ZnO shell on Zn nanoparticles

When exposed to air at room temperature, Zn nanoparticles oxidize gradually to form crystalline ZnO shells with a thickness of a few nanometers. Electron diffraction and high-resolution lattice imaging revealed that the ZnO layer on the Zn {0001} surface is composed of many epitaxial domains with small rotation angles relative to the lattice of the Zn core. The oxidized Zn particle bends when irradiated by the electron beam in a transmission electron microscope. This is due to the increase of internal stress in the ZnO layer as a result of the realignment of adjacent domains under electron beam irradiation. Corrosion of Zn nanoparticles was observed and the scaling and spalling start to occur on the {1010} prismatic faces.