Effects of Xe-ion irradiation at high temperature on single crystal rutile

Rutile (TiO2) single crystals with (1 1 0) orientation were irradiated with 360 keV Xe2+ ions at 923 K to fluences ranging from 7×1014 to 1×1016 Xe/cm2. Damage accumulation and evolution were analyzed using Rutherford backscattering spectroscopy combined with ion channeling analysis, and cross-sectional transmission electron microscopy. TiO2 crystals were found to exhibit a layer-like damage structure after irradiation, with up to three characteristic layers: (1) a thin surface layer denuded of defects; (2) a second layer centered at the peak damage position, consisting of small voids about 1–3 nm in diameter; and (3) a third, deeper layer consisting of large defects such as dislocations and dislocation loops. The defect-denuded layer at the surface results from point defect diffusion and annealing. The voids in the second layer may be attributed to aggregation of vacancies. Point defect migration and precipitation is also responsible for the large defects observed in the deepest layer within the irradiated microstructure. Amorphization was not observed in the crystals irradiated at this high temperature.