Growth and oxidation of a Ni3Al alloy on Ni(1 0 0)

The growth and oxidation of a thin film of Ni₃Al grown on Ni(1 0 0) were studied using Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and high resolution electron energy loss spectroscopy (EELS). At 300 K, a 12 Å thick layer of aluminium was deposited on a Ni(1 0 0) surface and subsequently annealed to 1150 K resulting in a thin film of Ni₃Al which grows with the (1 0 0) plane parallel to the (1 0 0) surface of the substrate. Oxidation at 300 K of Ni₃Al/Ni(1 0 0) until saturation leads to the growth of an aluminium oxide layer consisting of different alumina phases. By annealing up to 1000 K, a well ordered film of the Al₂O₃ film is formed which exhibits in the EEL spectra Fuchs-Kliewer phonons at 420, 640 and 880 cm⁻¹. The LEED pattern of the oxide shows a twelvefold ring structure. This LEED pattern is explained by two domains with hexagonal structure which are rotated by 90° with respect to each other. The lattice constant of the hexagonal structure amounts to ∼2.87 Å. The EELS data and the LEED pattern suggest that the γ^′-Al₂O₃ phase is formed which grows with the (1 1 1) plane parallel to the Ni(1 0 0) surface.