Radiation-induced defect clusters in fully stabilized zirconia irradiated with ions and/or electrons

Microstructure evolution of yttria-stabilized cubic zirconia (YSZ), ZrO2–13 mol% Y2O3, was investigated through transmission electron microscopy under irradiation with electrons and/or ions. Anomalous formation of large defect clusters was found under electron irradiation subsequent to ion irradiation, such as 300 keV O+, 100 keV He+ and 4 keV Ar+ ions. Such defect clusters were not formed solely with ion irradiation. The extended defect clusters possess strong black/black lobes contrast, and are observed preferentially around a focused electron beam at or near dislocations at temperature less than 520 K. The defect clusters were transformed into dislocation network when they reached a critical diameter of about 1.0–1.5 μm, and processes of nucleation, growth and transformation were repeated under electron irradiation. The defect clusters are assumed to be oxygen platelets induced through selective displacements of oxygen ions in YSZ with electron irradiation. An important role of the accumulation of electric charges due to the selective displacements in YSZ is also discussed.