We have performed a first-principles study of the structural, dynamical, and dielectric properties of j-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 j-Al2O3. Using our calculated results of j-Al2O3,together with the previous theoretical results of a-Al2O3 and available experimental data of amorphous Al2O3, we demonstrate the coordination dependence of ionic contribution to static dielectric constant of Al2O3.

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