The microscopic structure of a prismatic Σ3 (10•0) twin boundary in α-Al2O3 was characterized by combining ab initio local-density-functional theory, electron energy-loss spectroscopy measuring energy-loss near-edge structures of the O K-ionization edge, and high-resolution transmission electron microscopy. Theoretically, two distinct microscopic boundary variants with very low interface energies were derived and analyzed. The interface-projected densities of states calculated for the 2 variants agree equally well with energy-loss near-edge structures, therefore the comparison between experimental energy-loss near-edge structures and theoretical projected densities of states could not discriminate the one or the other boundary structure. The analysis reveals that the distinction between the metastable interfaces from energy-loss near-edge structures was limited by the spatial resolution of the scanning transmission electron microscope used to measure energy-loss near-edge structures, not by its energetic resolution. The quantitative analysis of experimental high-resolution transmission electron microscopic images obtained with an atomic-resolution microscope yields that the experimentally observed interface corresponded to the boundary variant with the lowest energy.

Prismatic Σ3 (10•0) Twin Boundary in α-Al2O3 Investigated by Density Functional Theory and Transmission Electron Microscopy. S.Fabris, S.Nufer, C.Elsässer, T.Gemming: Physical Review B, 2002, 66[15], 155415 (8pp)