Phase transformation of polycrystalline zirconia induced by swift heavy ion irradiation

Polycrystalline samples of monoclinic zirconia (α-ZrO2) have been irradiated at room temperature with 190 MeV 36Ar and 170 MeV 84Kr ions in the electronic slowing down regime. Room-temperature X-ray diffraction (XRD) and micro-Raman spectroscopy measurements show consistently that a phase transition to the tetragonal form (β-ZrO2) occurs for 170 MeV 84Kr ion irradiation above an electronic stopping power value around 15 MeV μm−1. The kinetics of the transition were monitored by on-line XRD measurements on the same sample. No such phase transformation is seen with 190 MeV 36Ar ion irradiation for an electronic stopping power value around 6 MeV μm−1. The plot of the tetragonal phase fraction deduced from XRD measurements vs fluence is analysed with single-impact and double-impact kinetic models. The data seem to be in favour of a double ion impact process.