Yttrium-doped zirconia bicrystals with [001] symmetrical tilt Σ5 grain boundaries were fabricated by a diffusion bonding technique, and O diffusion behavior across the grain boundary was measured by secondary ion mass spectrometry, tracing 18O isotope. It was found that the 18O fraction across the boundary exhibited explicit decrease around the boundary plane, indicating that the oxygen-diffusion was blocked by the presence of the Σ5 grain boundary. This was the first experimental detection of O diffusion blocking at a single grain boundary in zirconia ceramics. From high-resolution transmission electron microscopy observations and energy dispersive X-ray spectroscopy analysis, neither amorphous layers nor Si impurity segregation were found at the grain boundary. The grain boundary blocking effect of the Σ5 boundary must be an intrinsic feature arising from its core structure and yttrium solute segregation of the grain boundary.

Oxygen Diffusion Blocking of Single Grain Boundary in Yttria-Doped Zirconia Bicrystals. T.Nakagawa, I.Sakaguchi, N.Shibata, K.Matsunaga, T.Yamamoto, H.Haneda, Y.Ikuhara: Journal of Materials Science, 2005, 40[12], 3185-90