Segregation of yttrium ions to domain boundaries of tetragonal zirconia

The domain structures in tetragonal zirconia (t-ZrO2) formed by the diffusionless cubic-to-tetragonal transformation have been examined in ZrO2-3mol%Y2O3-12mol%-TiO2, which has a wide single t-ZrO2 field. During annealing in the single-phase field, the domain boundaries with antiphase boundary-like contrast tend to be facetted with a habit plane close to one of the {111} planes. Transmission electron microscopy-energy-dispersive spectroscopy analysis shows that yttrium ions segregate to the domain boundaries. Since the domain boundaries have a cubic structure, they must be stabilized by the segregation of yttrium ions, which are known to stabilize cubic zirconia.