Defect Structure Modification in Zirconia by Alumina

To high purity 8 mol% Y2O3 doped ZrO2, 0–0.6 mol% Al2O3 were added. The microstructures were characterized by SEM, and the electrical properties were measured by impedance spectroscopy. The bulk resistivity increases with increasing Al2O3 content, the grain boundary resistivity and the grain boundary thickness also increase with increasing Al2O3 content, which is mainly due to the decreasing concentrations of free oxygen vacancies in the bulk and at the grain boundaries as a result of the Al2O3 addition. Possible concentration variations of the other defects, e.g. Y′Zr, Al′Zr, (Y′ZrV••O)••, (Al′ZrV••O)•, (Y′ZrV••OY′Zr)x and (Al′ZrV••OAl′Zr)x in the bulk and at the grain boundaries are also suggested.