The grain-boundary structure and chemical composition in 8mol%Y2O3 bicrystals were studied by means of high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. Bicrystals with several types of [001] tilt boundary were prepared by joining two single crystals at 1400C, under a pressure of 3MPa. In all types of bicrystal, 2 crystals were perfectly connected so as to form grain boundaries having no second phases. From high-resolution transmission electron microscopic studies, the grain-boundary structure of a small-angle boundary with a rotation angle of 7º was found to be constructed from an array of grain-boundary dislocations having a Burgers vector of ½[110]-type, at an interval of about 3nm. On the other hand, periodic structures were observed at every 2.5 and 1.5 unit lattice along the grain boundaries of Σ = 13a and Σ = 5 bicrystals, respectively. Energy-dispersive X-ray spectroscopy showed that the segregation of doped Y occurred; depending upon the grain orientation relationship. It was shown that the amount of segregated Y increased with a decrease in the coherency of grain boundaries.

Grain Boundary Structure in 8mol%Y2O3-ZrO2 Bicrystals. Y.Ikuhara, T.Yamamoto: Annual Report of the Engineering Research Institute, School of Engineering, University of Tokyo, 2000, 58, 183-7