Cation segregation in an oxide ceramic with low solubility: Yttrium doped α-alumina

Gülgün, M.A., Voytovych, R., Maclaren, I. , Rühle, M. and Cannon, R.M. (2002) Cation segregation in an oxide ceramic with low solubility: Yttrium doped α-alumina. Interface Science, 10(1), pp. 99-110. (doi: 10.1023/A:1015268232315)

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The segregation behaviour of a cation (yttrium) with a low solubility in the polycrystalline oxide host (α-Al2O3) has been investigated at temperatures between 1450 and 1650°C using analytical scanning transmission electron microscopy. Three distinct segregation regimes were identified. In the first, the yttrium adsorbs to all grain boundaries with a high partitioning coefficient, and this can be modelled using a simple McLean-Langmuir type absorption isotherm. In the second, a noticeable deviation from this isotherm is observed and the grain boundary excess reaches a maximum of 9 Y-cat/nm2 and precipitates of a second phase (yttrium aluminate garnet, YAG) start to form. In the third regime, the grain boundary excess of the cation settles down to a value of 6–7 Y-cat/nm2 that is in equilibrium with the YAG precipitates. In a material (accidentally) co-doped with Zr, the Zr seems to behave in a similar way to the Y and the Y + Zr grain boundary excess behaves in the same way as the Y grain boundary excess in the pure Y-doped system. In this latter system, Y-stabilised cubic zirconia is precipitated in addition to YAG at higher Y + Zr concentrations.

Item Type:Articles
Glasgow Author(s) Enlighten ID:MacLaren, Dr Ian
Authors: Gülgün, M.A., Voytovych, R., Maclaren, I., Rühle, M., and Cannon, R.M.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Interface Science
Publisher:Kluwer Academic Publishers
ISSN (Online):1573-2746

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