IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Friday Sessions
       Session SS3-FrM

Paper SS3-FrM5
Metal Nucleation and Adhesion on Ionic-Oxide Terraces*

Friday, November 2, 2001, 9:40 am, Room 122

Session: Clean and Adsorbed Surfaces
Presenter: D.R. Jennison, Sandia National Laboratories
Authors: D.R. Jennison, Sandia National Laboratories
A. Bogicevic, Ford Research Laboratory
A.E. Mattsson, Sandia National Laboratories
Correspondent: Click to Email
We present two topics: First, it has recently been proposed@footnote 1@ that oxide surfaces with a substantial number of oxygen vacancies may show greatly increased adhesion. It has also been observed that metal islands nucleate not only at line defects, but also on oxide terraces. Using first-principles DFT, we previously@footnote 2@ studied the Pt dimer on MgO(100), and found that neither the O nor the Mg vacancy increased its stability, and in fact the dimers were only marginally stable at room temperature. We have now extended this study to include the dimers of eight different metals, both on the clean surface and at the O vacancy. We find that not all metals behave similarly! In fact, the dimers of Ag and Au are much more tightly bound on the clean surface than are those of Pd or Pt, and actually increase their stability at the defect. We understand these results based on dimer electronic structure. The second topic concerns the accuracy of DFT for studies of metal/oxide interfaces where the metal binds mostly by polarization, i.e. where there are no significant chemical bonds. This bonding is much stronger than van der Waals and it is measurable by analysis of the Wulff shapes of metal nanoparticles.@footnote 3@ In the cases of Pd and Cu on alumina films, DFT in the LDA predicts a work of adhesion close to experiment,@footnote 3@ while the GGA fails badly (and differs by about 50%). We have now understood this unusual failure of GGA in terms of the surface self-exchange error in DFT, as evidenced recently for another metal.@footnote 4@ In fact, the experimental result, vs. the computational numbers, supports our previous assertion@footnote 5@ that the interfacial binding of most metals on ionic oxides is mainly due to polarization. @FootnoteText@@footnote 1@Y. F. Zhukovskii, et al., PRL 84 (2000) 1256. @footnote 2@A. Bogicevic and D. R. Jennison, Surf. Sci. 437 (1999) L741. @footnote 3@K. H. Hansen, et al., PRL 83 (1999) 4120; T. Worren et al., Surf. Sci. 477 (2001) 8. @footnote 4@K. Carling, et al., PRL 85 (2000) 3862. @Footnote 5@C. Verdozzi, et al., PRL 82 (1999) 4050; A. Bogicevic and D. R. Jennison, PRL 82 (1999) 799. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000; www.sandia.gov/surface_science/drj/.Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000; www.sandia.gov/surface_science/drj/.