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Published online by Cambridge University Press: 21 March 2011
Bulk Density Functional Theory calculations were performed on Hf and Zr substitutions for Al in κ-alumina. The lowest energy configuration found was an octahedrally coordinated Zr site. Zr dissolution was favorable with an enthalpy of -2eV/unit cell for forming Al1.875Zr0.125O3 from pure Zr and κ-alumina. Hf and Zr substitution for Al atoms introduced empty d-states below the conduction band edge reducing the Eg of pure κ-alumina (7.5eV) to 6.4-5.9eV. The edge of the valence band however remained fixed by the O p-state character. The substitution of Hf and Zr into the alumina structure may lead to a higher dielectric constant, but will also reduce Eg and result in a trade off in tunneling currents in devices.