{ital Ab initio} structural predictions for ultrathin aluminum oxide films on metallic substrates
- Sandia National Laboratories, Albuquerque, New Mexico 87185-1413 (United States)
On several metallic substrates, first-principles density-functional calculations of Al{sub 2}O{sub 3} 5{endash}7 {Angstrom} films predict a structure, stabilized by interfacial electrostatics, which has no bulk counterpart. In two and three O-layer films, Al ions prefer distorted {ital tetrahedral} sites, over the normal octahedral sites. The film/substrate interface is found to consist of strongly chemisorbed oxygen and is the determining factor in geometry; these oxygens are only weakly perturbed by the presence of Al{sub 2}O{sub 3} overlayers. In an experimentally relevant film (two O layers, as on NiAl), Al ions are nearly coplanar with surface O ions; thus observing {open_quotes}oxygen termination{close_quotes} does not indicate a polar surface. As a test case, we find Pt overlayers bind similarly as to {alpha}-Al{sub 2}O{sub 3}, suggesting these films may indeed be useful models for thicker materials. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 351880
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 24 Vol. 59; ISSN 0163-1829; ISSN PRBMDO
- Country of Publication:
- United States
- Language:
- English
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