Abstract
Defect studies of a ZrO2 + 9 mol. % Y2O3 single crystal were performed in this work using a high resolution positron lifetime spectroscopy combined with slow positron implantation spectroscopy. Ab initio theoretical calculations indicated that zirconium vacancies are the only deep positron traps and are most probably responsible for the saturated positron trapping observed in yttria stabilized zirconia single crystals.
The calculated positron lifetime for zirconium vacancy is apparently longer than the experimental value. This effect can be explained by hydrogen trapped in zirconium vacancies.
On the basis of structure relaxations, we found that zirconium vacancy – hydrogen complexes represent deep positron traps with the calculated lifetime close to the experimental one. In zirconium vacancy – hydrogen complexes the hydrogen atom forms an O-H bond of 1 A length with one of the nearest neighbour oxygen atoms.