Theoretical Structure Determination of a Complex Material: κ-Al2O3

The atomic and electronic structures of kappa‐Al2O3 are determined using theoretical first‐principles techniques based on density‐functional theory (DFT), plane waves, and pseudopotentials. The obtained structure is confirmed by analysis of powder X‐ray diffraction data. The structure is orthorhombic with oxygen ions in close‐packed ABAC stacking and aluminum ions occupying both tetrahedral (1/4) and octahedral (3/4) interstitial sites. A growth model for chemical vapor deposition of kappa‐Al2O3 is proposed based on the atomic structure. Calculated electronic structure and charge density yield a band gap of 5.3 eV and a high ionic character of the bonds. The study shows the applicability of DFT‐based methods to complex and metastable materials.