Study of Oxygen Vacancies in Ceramics by Perturbed Angular Correlation Spectroscopy

Perturbed angular correlation (PAC) measurements in tetragonal and cubic zirconia and in ceria are described. A physically reasonable and self‐consistent interpretation of these data implies that oxygen vacancies are trapped at a second‐neighbor position by Cd in tetragonal zirconia and by In in ceria. For Cd in tetragonal zirconia, the vacancy trap energy is found to be 0.44 eV, and the energy barrier between adjacent trap sites is approximately 0.8 eV. The activation energy of an oxygen vacancy hopping between trap sites around ¹¹¹Cd in ceria is found to be 0.55 eV. The activation energy for oxygen vacancy hopping in cubic zirconia, as detected by ¹⁸¹Ta PAC, is about 1.0 eV and independent of the Y concentration.