Thermal annealing study of swift heavy-ion irradiated zirconia

Sintered samples of monoclinic zirconia (α-ZrO2) have been irradiated at room temperature with 6.0-GeV Pb ions in the electronic slowing down regime. X-ray diffraction (XRD) and micro-Raman spectroscopy measurements showed unambiguously that a transition to the ‘metastable’ tetragonal phase (β-ZrO2) occurred at a fluence of 6.5x10 cm for a large electronic stopping power value (≈ 32.5 MeV μm). At a lower fluence of 1.0x10 cm, no such phase transformation was detected. The back-transformation from βto α-ZrO2 induced by isothermal or isochronal thermal annealing was followed by XRD analysis. The back-transformation started at an onset temperature around 500 K and was completed by 973 K. Plots of the residual tetragonal phase fraction deduced from XRD measurements versus annealing temperature or time are analyzed with firstor second-order kinetic models. An * Corresponding author : [email protected]