Swelling effects in Y ₂Ti ₂O ₇ pyrochlore irradiated with 400 keV Ne ²⁺ ions

Polycrystalline pyrochlore Y ₂Ti ₂O ₇ compounds were irradiated with 400 keV Ne ²⁺ ions at cryogenic temperature (∼77 K) at fluences ranging from 5 × 10 ¹⁴ to 1 × 10 ¹⁶ ions/cm ², 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.