Epitaxial alloyed films out of the bulk stability domain: Surface structure and composition of Ni3Al and NiAl films on a stepped Ni(111) surface

SURFACE SCIENCE

卷:604

Article

Prevot, G.¹  Schmaus, D.^1,2  Le Moal, S.³ 

[1] Univ Paris 06, Inst NanoSci Paris, CNRS, UMR 7588, F-75015 Paris, France

[2] Univ Paris 07, F-75015 Paris, France

[3] Tech Univ Munich, Lehrstuhl Phys Chem, D-85747 Garching, Germany

关键词: Nickel;    Aluminium;    Alloy;    Growth;    Epitaxy;    Spot Profile Analysis Low Energy Electron Diffraction (SPA-LEED);    Auger Electron Spectroscopy (AES);   

DOI  :  10.1016/j.susc.2010.01.025

来源: Elsevier

【 摘 要 】

We have studied by Spot Profile Analysis Low Energy Electron Diffraction (SPA-LEED) and Auger Electron Spectroscopy (AES) Ni-Al alloyed layers formed by annealing, around 780 K, Al deposits on a stepped Ni(1 1 1) surface. The surface structure and composition of the thin epitaxial Ni3Al and NiAl films, obtained respectively below and above a critical Al initial coverage theta(c), differ markedly from those of corresponding bulk alloys. The Ni3Al ordered films form in a concentration range larger than the stability domain of the L1(2) Ni3Al phase. The NiAl films present a marked distortion with respect to the lattice unit cell of the B2 NiAl phase, which slowly decreases when the film thickness increases. It also appears that the value of theta(c) depends on the morphology of the Ni(1 1 1) substrate, increasing from theta(c) = 4.5 ML for a flat surface to theta(c) = 10 ML for a surface with a miscut of 0.4 degrees. This could be directly related to the presence of steps, which favour Ni-Al interdiffusion. (C) 2010 Elsevier B.V. All rights reserved.

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