The effect of substrate surface nature on texture formation in nickel oxide

X-ray diffraction was used to study the influence of surface finishing on polycrystalline nickel and its modification with ultra-fine dispersions of CeO2 on crystallographic texture development in NiO scales, grown at 1073 K in 760 torr oxygen for time periods up to 75 h. Ni substrate characterized by {1 0 0}[0 2 3] texture and surface with an atomic structure revealed by chemical polishing led to the formation of NiO with {1 0 0}[0 1 3] texture, indicating an epitaxial growth. After applying CeO2 on the Ni surface prior to the oxidation, no essential changes in NiO texture were detected. When the Ni surface was deformed by mechanical polishing, NiO exhibited a fibre texture with a major component of [1 1 0] oriented along the growth direction. The presence of CeO2 on this substrate changed the dominant fibre axis to [1 0 0]. The texture data are discussed in terms of the oxide microstructures and their growth kinetics. In particular, for CeO2-modified NiO scales with complex depth structure, the possible contribution of individual sublayers to the overall measured texture is estimated. (C) 1998 Kluwer Academic Publishers.