Terraced Hollow Oxide Pyramids
0031-9007= We report in situ transmission electron microscope dynamic observations of the growth of Cu2O islands during oxidation of (001)Cu thin films at 900 C, which show that the oxide islands have an initially square shape that transits to a terraced pyramid morphology as growth proceeds. The surface topology obtained from ex situ atomic force microscopy observation indicates that the terraced oxide pyramids have a hollow structure. A simple mechanical mechanism based on elastic-plastic deformation is proposed to explain the formation of this completely new oxide structure.