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Comparative study of electronic structures and dielectric properties of alumina polymorphs by first-principles methods

Title
Comparative study of electronic structures and dielectric properties of alumina polymorphs by first-principles methods
Authors
Lee C.-K.Cho E.Lee H.-S.Seol K.S.Han S.
Ewha Authors
한승우
Issue Date
2007
Journal Title
Physical Review B - Condensed Matter and Materials Physics
ISSN
1098-0121JCR Link
Citation
vol. 76, no. 24
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
Based on density functional methods, we investigate the origin of variations in electronic structures and dielectric constants of representative alumina polymorphs. We consider the most stable α- Al2 O3 and three metastable phases of alumina, κ, θ, and γ- Al2 O3. Computed energy gaps are found to be in the order of α>κ>θ> γ, which can be understood based on electrostatic potentials at specific lattice sites; while cations occupying tetrahedral sites explain downshifts of conduction bottoms in the metastable alumina, vacant sites in γ- Al2 O3 account for the gap reduction originated in the valence band. On the other hand, dielectric properties are also calculated based on density functional perturbation methods. On average, the static dielectric constants follow the order of κ>α>θ>γ. The substantial enhancement of the dielectric constant for κ- Al2 O3 is attributed to elongated Al-O bonds due to a simultaneous occupation of tetrahedral and octahedral sites by cations within a single layer. © 2007 The American Physical Society.
DOI
10.1103/PhysRevB.76.245110
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자연과학대학 > 물리학전공 > Journal papers
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