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α‐Al 2 O 3 (0001) Surfaces: Atomic and Electronic Structure
Author(s) -
Gautier Martine,
Fenaud Gilles,
Pham Van Laurent,
Villette Bruno,
Pollak Maud,
Thromat Nathalie,
Jollet François,
Duraud JeanPaul
Publication year - 1994
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1994.tb06999.x
Subject(s) - spectroscopy , auger electron spectroscopy , electronic structure , x ray absorption spectroscopy , surface reconstruction , x ray photoelectron spectroscopy , electron spectroscopy , electron energy loss spectroscopy , scattering , atomic physics , chemistry , low energy electron diffraction , molecular physics , materials science , electron , crystallography , absorption spectroscopy , surface (topology) , electron diffraction , diffraction , physics , optics , nuclear magnetic resonance , geometry , computational chemistry , mathematics , quantum mechanics , nuclear physics
New results on the R ± 9° reconstructed α‐Al 2 O 3 (0001) surface, which can be obtained after heating at high temperature (1400°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 Å. 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 R ± 9° reconstructed surface is more covalent than the (1 × 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.