AFM Observations of Oxide Morphologies Formed at high Temperatures

Abstract

ABSTRACTThe growth surfaces of oxides formed at high temperatures on metallic substrates with different oxidation resistance were imaged using an atomic force microscope (AFM) in both contact and tapping modes. In addition to differences in morphology of NiO and TiO2 films, and their anisotropy of growth caused by the crystallographic orientation of substrate grains and by the type of substrate grain boundaries, some subtle growth features were documented. These include the nano-size steps of growth on the sidewalls of pyramidal grains of TiO2 and the nucleation at the intersection of NiO grain boundaries with NiO/gas interface. An example of a quantitative description of oxide/gas interface using roughness parameters is presented. This description is used to demonstrate the differences in evolution of oxide growth morphology for NiO doped with Ce growing by inward diffusion of oxygen anions or by outward diffusion of metal cations.