Abstract

We have performed a first-principles study of the structural, dynamical, and dielectric properties of κ-Al₂O₃. The relaxed structural parameters are found to be in excellent agreement with experimental data. Using density-functional perturbation theory, we obtain the Born effective charge tensors, the phonon frequencies at the center of the Brillouin zone, and the electronic and static dielectric permittivity tensors of κ-Al₂O₃. Using our calculated results of κ-Al₂O₃, together with the previous theoretical results of α-Al₂O₃ and available experimental data of amorphous Al₂O₃, we demonstrate the coordination dependence of ionic contribution to static dielectric constant of Al₂O₃.