High-dielectric constant oxides are the focus of intense current research. As a contribution to the rationalization of the search for candidate materials, we compare the dielectric properties obtained from first-principles linear-response calculations for two phases-the ground state bixbyite and the competing hexagonal structures-of the crystalline oxide Lu2O3. The dielectric constants of bixbyite is about 12 and that of hexagonal is about 19 (the electronic constant being about 4.5 in both cases). This difference is due almost exclusively to the vibrational properties, with minor or no influence of charge anomaly differences; as these are related mainly to oxygen vibrations, we argue that the dielectric properties of sesquioxides will be determined mostly by their preferred structure, i.e. they will be poorer for bixbyite (e.g. Y2O3) than for hexagonal (e.g. La2O3) sesquioxides. (c) 2004 Elsevier Ltd. All rights reserved.
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