Multistep damage evolution process in cubic zirconia irradiated with MeV ions

This work reports the study, via the combination of Rutherford backscattering spectrometry and channeling, x-ray diffraction, and transmission electron microscopy experiments, of the damage formation in cubic yttria-stabilized zirconia single crystals irradiated with medium-energy (4 MeV) heavy (Au) ions. The damage buildup, which is accounted for in the framework of the multistep damage accumulation model, occurs in three steps. The first step at low fluences (up to 1015 cm−2), characterized by a regular increase in both the damage yield and the elastic strain, is related to the formation of small defect clusters. The second step in the intermediate fluence range (from 1015 to 5×1015 cm−2) leads to a sharp increase in the damage yield and to a large drop of the strain due to the formation of dislocation loops which collapse into a network of tangled dislocations. The third step at high fluences (above 5×1015 cm−2) exhibits a surprising decrease in the damage yield, which may be attributed to the reorganization of the dislocation network that leads to the formation of weakly damaged regions with a size of the order of 100 nm.