Swelling effects in Y2Ti2O7 pyrochlore irradiated with 400Â keV Ne2+ ions

Polycrystalline pyrochlore Y2Ti2O7 compounds were irradiated with 400 keV Ne2+ ions at cryogenic temperature (∼77 K) at fluences ranging from 5 × 1014 to 1 × 1016 ions/cm2, corresponding to a peak ballistic damage dose of ∼0.17-3.4 displacements per atom (dpa). Irradiation-induced structural evolution was examined using grazing incidence X-ray diffraction at X-ray incident angles from 0.25° to 3° and cross-sectional transmission electron microscopy. An apparent swelling effect was observed on the irradiation layer prior to the irradiated layer being amorphized. The swelling effect increased with increasing ion irradiation fluence. At an ion induced damage of 1.7 dpa, the irradiated layer started to be amorphized.