THE CORRELATION BETWEEN THE SURFACE-ROUGHNESS AND GROWTH-MECHANISM INTHIN NIO FILMS MODIFIED BY CEO2

The surface topography of thin NiO films formed in the temperature ran ge of 873-1073 K on pure and on CeO2 coated polycrystalline Ni has bee n analyzed quantitatively using atomic force microscopy. Oxides with a verage thicknesses of up to 950 nn exhibited topography which was depe ndent on the Ni surface finishing, the presence of CeO2 coatings, and oxide thickness. It has been found that a correlation exists between t he evolution of surface topography and the mechanism of oxide growth. For both pure NiO and NiO modified by CeO2, grown by predominantly out ward Ni2+ cation diffusion, surface roughness increased significantly with oxide thickness and oxidation temperature. By contrast, only smal l changes in roughness were detected for NiO modified by CeO2 and form ed by predominantly inward O2- anion diffusion. The results obtained a re discussed in terms of the influence of CeO2 additions and Ni surfac e finishing on the growth morphology of the NiO films. Copyright (C) 1 996 Elsevier Science Ltd