Positron depth profiling in ion-implanted zirconia stabilized with trivalent cations

Slow positron implantation spectroscopy has been performed on a series of (ZrO2)(1-x)(M2O3), solid solutions, either stabilized in the cubic phase (with M:Y, Dy or Er and x = 0.095, 0.16 or 0.16, respectively) or in the tetragonal metastable phase (M:Y and x = 0.03). Stabilization induces native oxygen-vacancy complexes, which lead to saturation trapping of positrons in the cubic crystals, regardless of the cation type. The positron diffusion length in the tetragonal phase (L+ approximate to 60 nm, vs. approximate to 2.5 nm in the cubic phase) suggests that Y atoms segregate around antiphase boundaries formed in the lattice. Implantations of helium and oxygen ions induce new defects, more trapping effective than the native defects. However, their production rate and temperature stability seem primarily dependent on the crystal structure, hence on the concentration of trivalent cations, irrespective of their chemical nature.