2.7Â MeV Ar11+ ion irradiation induced structural evolution in Lu2(Ti2-xLux)O7-x/2 pyrochlores

This paper aims to study the radiation effects of nonstoichiometric pyrochlore series Lu2(Ti2-xLux)O7-x/2 (x = 0-0.667). Polycrystalline Lu2(Ti2-xLux)O7-x/2 samples were irradiated with 2.7 MeV Ar11+ ions up to a fluence of 8 × 1014 ions/cm2. The irradiated samples were characterized using grazing incidence X-ray diffraction technique. The results reveal that Lu2(Ti2-xLux)O7-x/2 samples undergo significant amorphization and lattice swelling upon irradiation. Specifically, the amorphization process is predominantly driven by ballistic nuclear energy deposition of Ar11+ ions at this energy regime, which can be well described by a direct-impact/defect-stimulated model. Both the amorphization fraction and the relative variation of lattice parameter decrease with increasing x, showing a strong dependence on the chemical composition. The results are then discussed in the framework of the structural disorder and recovery ability from damage, applying an atomic layer model.