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LEEM images showing the nucleation and growth of an alumina island on a NiAl (110) surface at in . The island nucleates at a monatomic substrate step, marked by the horizontal arrow in the image, and contains two translation-related domains. A vertical arrow marks the domain boundary. In the image, a second domain boundary (marked by arrow) nucleates and extends itself across the island. The island then contains three translation-related domains. NiAl directions are shown. Images are .
(a) Schematic illustration showing the in-plane orientations of the NiAl (110) surface and film. Only one of the two rotation-related domains of the film, labeled B following the convention of Kulawik et al. (Ref. 6), is shown. Boundaries between translation-related domains in the oxide film lie along the short side of the oxide’s unit cell (labeled TDB IB) or along one of the cell’s diagonals (TDB IIB). The vectors and give the relative displacements of the oxide lattices across the two types of TDBs. Neither of these vectors is a lattice vector of the NiAl surface. (b) Schematic illustration of the film/NiAl interface in cross section. The vertical tick marks represent lattice sites. The TDBs are planar defects, which are terminated at the film/substrate interface by dislocations (⊥ symbols). The lattice of the domain is offset by displacement relative to the surrounding film lattice. This displacement introduces a stacking fault at the film/substrate interface.
LEEM images at of an alumina patch formed by the abutment of two rotationally nonequivalent islands separated by a vertical boundary (marked by the arrow in the image). At , a sawtooth-shaped TDB separates two translation-related domains in the right island. As this oxide island grows in during the first three images, a second sawtooth-shaped TDB (marked by an arrow in the image) develops. The oxide island then contains three translation-related domains. After the image, the oxide was annealed in vacuum and a third TDB, marked with the arrow in the image, is introduced. NiAl directions are shown. Images are .
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