The atomic structures of 2 symmetrical [001] tilt grain boundaries, Σ5 (310) and near-Σ13 (510), in Y2O3-stabilized cubic ZrO2 were studied by means of Z-contrast scanning transmission electron microscopy. Both boundaries were composed of periodic arrays of highly symmetrical structural units; with a distinct unit for each boundary. The O K-edge electron energy-loss spectra showed that the O coordination was similar for the bulk and grain boundary; thus indicating that O ions within the grain boundary were situated in distorted tetrahedral sites. Atomic models for the grain boundaries were proposed which were consistent with the experimental data. The core structures were different to those of previously studied metal or oxide grain boundaries, and were unique to the fluorite structure. The segregation of Y to the grain boundaries was also investigated by means of electron energy-loss spectroscopy. The Y was found to segregate preferentially to the Σ5 grain boundary, and the spatial distribution of the segregation layer was confined to within 1nm of the boundary plane.

Structure and Chemistry of Yttria-Stabilized Cubic-Zirconia Symmetrical Tilt Grain Boundaries. E.C.Dickey, X.Fan, S.J.Pennycook: Journal of the American Ceramic Society, 2001, 84[6], 1361-8