Phase transformation of polycrystalline zirconia induced by swift heavy ion irradiation

Polycrystalline samples of monoclinic zirconia (alpha -ZrO2) have been irradiated at room temperature with 190 MeV Ar-36 and 170 MeV Kr-84 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 (beta -ZrO2) occurs for 170 MeV Kr-84 ion irradiation above an electronic stopping power value around 15 MeV mum(-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 Ar-36 ion irradiation for an electronic stopping power value around 6 MeV mum(-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. (C) 2001 Elsevier Science B.V. All rights reserved.