Transformation of YSZ under high fluence argon ion implantation

In this work, we present the effect of extremely high fluence ion implantation on microstructure of single crystalline YSZ samples with three major low index orientations: (1 0 0), (1 1 0) and (1 1 1). The samples were implanted at room temperature with 150 keV Ar+ ions to a fluence of 1 × 1017 Ar/cm−2 corresponding to the peak damage level of ∼120 dpa and peak Ar atom concentration of ∼12 at.%. Rutherford backscattering/channeling spectrometry (RBS/C), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and associated analytical tools were used to determine the orientation dependent damage, surface morphology, and microstructure modifications of the implanted layers. Ar+ ion implantation resulted in formation of severely damaged layers, which however remained crystalline. The damage peak maximum, determined by RBS/C, indicated that the fourth damage accumulation stage, previously predicted for Ar-implanted YSZ, was achieved. The (1 1 0) oriented YSZ demonstrated slightly better radiation tolerance, as observed by RBS/C, compared to the other low index orientations. Microstructural studies revealed large cavities aligned parallel to the specimen surface, which emerged in a form of circular blisters on the surface. The origin of the cavities was related to the segregation of Ar atoms into pressurized gas filled bubbles. The crystallographic anisotropy of microstructural parameters (thickness of the damages layer, surface blister density and diameter, cavity dimensions) remains uncertain.