Determination of the atomic structure of a ∑13 SrTiO3 grain boundary

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New elements of a symmetric [001] 67.4° SrTiO3 near ∑13 tilt grain boundary are identified by a quantitative analysis of lattice images, reconstructed electron exit waves, and HAADF images. The analysis reveals local, geometrical variations of structural grain boundary units that relate to the presence of defects introduced by a tilt deviation of 0.65 + 0.02 degrees from the perfect ∑13 geometry. Sr and TiO columns are discriminated in HAADF images while the reconstructed electron exit wave reveals all oxygen columns in addition. Both methods depict the crystal and boundary structure directly while lattice imaging with a high voltage instrument requires image simulations to link the image intensity to structure. For the first time we observe a Sr column splitting by 90 pm that supports theoretical predictions. An inhomogeneous, preferential etching at the grain boundary is attributed to local charge variations and hampers a quantitative investigation and local stoichiometry. The near ∑13 boundary forms a dense and compact structure with chemically identical columns in close proximity. Therefore, it is different from the relaxed, bulk like configurations described in previous reports.

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