Slow positron implantation spectroscopic investigations were made of yttria-stabilized cubic zirconia which had been implanted with 50keV He ions. These revealed, at 60% of the projected range, a maximum in the concentration of defects. This was thought to constitute a barrier to He diffusion towards the surface. The Doppler broadening line-shape dependence upon fluence suggested a change in the nature of defects above 4 x 1016/cm2; with an enhancement of trapping efficiency. These defects evolved into large bubbles, via Ostwald ripening, after annealing at above 573K; as suggested by their distribution narrowing. Above 973K, break-up of the bubbles occurred; with He release, and diffusion towards the surface with eventual out-gassing.

Fluence Dependence and Thermal Stability of Defects in Helium-Implanted Cubic Zirconia. S.Saudé, R.I.Grynszpan, W.Anwand, G.Brauer, J.J.Grob, Y.Le Gall: Nuclear Instruments and Methods in Physics Research B, 2004, 216[1], 156-60