Ageing and thermal recovery of paramagnetic centers induced by electron irradiation in yttria-stabilized zirconia

We have used electron spin resonance spectroscopy to study the defects induced in yttria-stabilized zirconia (YSZ) single crystals by 2.5-MeV electron irradiations. Two paramagnetic centers are produced: the first one with an axial symmetry is similar to the trigonal Zr 3+ electron center (T center) found after X-ray irradiation or thermochemical reduction, whereas the second one is a new oxygen hole center with an axial symmetry different from the orthorhombic O - center induced by X-ray irradiation. At a fluence around 10 18 e/cm , both centers are bleached out near 600 K, like the corresponding X-ray induced defects. At a fluence around 10 19 e/cm 2 , defects are much more stable, since complete thermal bleaching occurs near 1000 K. Accordingly, ageing of as-irradiated samples shows that high-dose defects at more stable than the low-dose ones.