The effect of Zr doping (1000ppm) upon fine-grained alumina was studied by means of high-resolution transmission electron microscopy and field emission scanning transmission electron microscopy. The high-resolution transmission electron microscopic observations revealed that the atomic structure of grain-boundary regions was not strongly distorted in comparison with the surrounding bulk. It was found that there was no amorphous phase at any of the grain boundaries. It was shown, using energy-dispersive X-ray spectroscopy, that Zr segregated to the grain-boundary regions; with a Zr/Al atomic ratio of 1.6%. Normalization and subtraction of matrix spectra from the interface spectra revealed features which were attributed to heavily misshapen defects at the boundary.

K.Kaneko, T.Gemming, I.Tanaka, H.Müllejans: Philosophical Magazine A, 1998, 77[5], 1255-72