Crystal orientation mapping of NiO grown on cube textured Ni tapes

Abstract

SummarySamples of cube textured Ni tapes were oxidized in flowing oxygen at different temperatures. Crystal orientation maps (COMs) of the resulting oxide layers were produced by electron backscatter diffraction. The oxide layers were also analysed by X-ray diffraction (XRD), scanning electron microscopy and atomic force microscopy (AFM). The oxide grain size of a sample oxidized at 600 ° C was similar to that of the substrate and the oxide was highly textured, both indicating epitaxial growth. The orientation relationship between the substrate and the oxide was directly observed from XRD to be (111) NiO //(001) Ni , [ ! 01] NiO //[110] Ni with four, equivalent, in-plane variants. In each variant, the oxide has both <110>-and <211>-type directions parallel to the Ni <110> directions. Differences in oxide thickness and surface roughness on neighbouring grains were revealed by AFM and these were attributed to the existence of a range of oxide growth conditions resulting from small differences in the orientation of each substrate grain. Similar macrotexture and microstructure were observed on a sample oxidized at 1300 ° C, but additional, facetted oxide crystals had formed at the oxide grain boundaries. COMs showed that these crystals were either cube or 45 ° rotated cube orientated, a texture different to that of the large oxide grains. The grain boundary crystals were thought to form by inward diffusion of oxygen at defects in the growing oxide scale.

A Template and Catalyst-Free Metal-Etching-Oxidation Method to Synthesize Aligned Oxide Nanowire Arrays: NiO as an Example

“…It has been reported that in the oxidation of highly textured Ni tapes the crystallographic orientation of the NiO grains is closely correlated with that of the Ni grains underneath. 35 Therefore, the annealing process prior to the NW growth helps to produce highly textured Ni foils and warrants the crystalline alignment of the produced NiO NW arrays. Furthermore, the NiO scale with fine channels limits the reaction rate and helps to protect the Ni foil from being etched excessively.…”

“…During this process, the electric field of more than 10 6 V cm −1 developed between Ni and NiO, along with the giant mechanical stress at the interface, may assist the self-organized formation of the NiO NW arrays. It has been reported that in the oxidation of highly textured Ni tapes the crystallographic orientation of the NiO grains is closely correlated with that of the Ni grains underneath . Therefore, the annealing process prior to the NW growth helps to produce highly textured Ni foils and warrants the crystalline alignment of the produced NiO NW arrays.…”

Direct Oxidation Growth of CuO Nanowires from Copper‐Containing Substrates

“…[9]. The two observed fringe directions may be attributed to the difference in surface orientation or surface roughness of the corresponding substrates [18,19]. The direction in which a crystal grows on a substrate is dependent on the orientation of the seed crystal.…”

Growth Mechanism and Magnetic Properties of Highly Crystalline NiO Nanocubes and Nanorods Fabricated by Evaporation

“…It was reported that the (100) surfaces were the most readily oxidized at high temperature. 35,36 The reason nanocrystal growth governed by the VS process usually yields nanostructures with faceted shapes that consist of certain low index crystallographic planes is not clear in the present study. However, this method has some unique features compared with other existing physical approaches for growing nanocrystals of oxides or non-oxides.…”