[alpha]-Al[sub 2]O[sub 3] (0001) surfaces: Atomic and electronic structure
- Centre d'Etudes de Saclay, Gif-sur-Yvette (France)
- Centre d'Etudes de Grenoble (France)
New results on the ([radical]31 [times] [radical]31) R[+-]9[degree] reconstructed [alpha]-Al[sub 2]O[sub 3] (0001) surface, which can be obtained after heating at high temperature (1,400 C) under vacuum, are presented. The atomic structure has been studied by combining low-energy electron diffractometry and grazing incidence X-ray scattering. The surface structure is found to be perfectly commensurable with the underlying bulk lattice. The surface consists of hexagonal zones of two, nearly perfect, close-packed Al (111) planes separated by a defect of hexagonal periodicity with a parameter of 26.44 [angstrom]. This model is consistent with previous surface studies of this reconstruction. The electronic structure has been investigated using valence band photoemission spectroscopy, X-ray absorption spectroscopy at the O K edge, electron energy loss spectroscopy, and X-ray-induced Auger electron spectroscopy. Interpretation of these experimental data in the frame of a self-consistent, tight-binding calculation leads to the conclusion that the ([radical]31 [times] [radical]31) R[+-]9[degree] reconstructed surface is more covalent than the (1 [times] 1) surface. Significant changes in the Al-O hybridizations are observed; these are likely due to a difference in the interatomic distances along the [0001] axis (relaxations). The increase of covalent character is mainly due to a strong decrease of the Madelung field on the reconstructed surface.
- OSTI ID:
- 7207496
- Journal Information:
- Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 77:2; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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