First-principles calculation of electronic, optical, and structural properties of [alpha]-Al[sub 2]O[sub 3]

Journal Article · Tue Feb 01 04:00:00 EST 1994 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1994.tb07008.x· OSTI ID:7207483

Ching, W Y; Xu, Y N ^[1]

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1. Univ. of Missouri, Kansas City, MO (United States). Dept. of Physics

The electronic structure, the linear optical properties, and the structural properties of [alpha]-Al[sub 2]O[sub 3] in the corundum structure are studied by means of first-principles local density calculations. An indirect band gap of 6.29 eV is obtained, which is almost the same as the direct band gap of 6.31 eV at [Gamma]. The calculated density of states are compared with X-ray photoemission and photoabsorption measurements. Real space charge density analysis shows Al[sub 2]O[sub 3] to be highly ionic with an effective charge formula of Al[sub 2][sup +2.75]O[sub 3][sup [minus]1.83]. The calculated dielectric function is in general agreement with the experimental vacuum ultraviolet data. It is shown that the component with c-direction polarization is in better agreement with the experimental data because it is less affected by the exciton formation near the absorption edge. Various careful test calculations indicate that the remaining discrepancy in the optical spectra may be in the LDA approximation of the electronic structure theory. The total energy calculation for the ground-state structural properties of [alpha]-Al[sub 2]O[sub 3] shows excellent agreement with experimental data: the calculated equilibrium volume, c/A ratio, bulk modulus, and internal parameters for Al and O atoms differ from measured values by 0.0, [minus]4.3, [minus]4.0[minus], 0.85, and 1.96 percent, respectively. The calculations for the electronic structure and the optical properties are repeated with crystal parameters obtained at 2000 C.

• DOE Contract Number: FG02-84ER45170
• OSTI ID: 7207483
• 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

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CALCULATION METHODS
CHALCOGENIDES
CORUNDUM
ELECTRONIC STRUCTURE
MINERALS
OPTICAL PROPERTIES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SAPPHIRE