The correlation between the surface roughness and growth mechanism in thin NiO films modified by CeO2

The surface topography of thin NiO films formed in the temperature range of 873-1073 K on pure and on CeO2 coated polycrystalline Ni has been analyzed quantitatively using atomic force microscopy. Oxides with average thicknesses of up to 950 nn exhibited topography which was dependent on the Ni surface finishing, the presence of CeO2 coatings, and oxide thickness. It has been found that a correlation exists between the evolution of surface topography and the mechanism of oxide growth. For both pure NiO and NiO modified by CeO2, grown by predominantly outward Ni2+ cation diffusion, surface roughness increased significantly with oxide thickness and oxidation temperature. By contrast, only small changes in roughness were detected for NiO modified by CeO2 and formed by predominantly inward O2- anion diffusion. The results obtained are discussed in terms of the influence of CeO2 additions and Ni surface finishing on the growth morphology of the NiO films. Copyright (C) 1996 Elsevier Science Ltd