Defect chemistry manipulation by heavy ion irradiation in Y-doped CeO₂ solid solutions

A combination of experimental methods is used to study the effect of trivalent cation doping and radiation stability of Y-doped CeO₂ with dopant content ranging from 0-15 wt%. X-ray diffraction reveals that Y-incorporation leads to long-range ordering of anionic vacancies with randomly distributed C-type Y₂O₃ nanodomains that form coherently within the host fluorite structure. Raman and positron annihilation spectroscopies are employed to characterise and analyse the nature of oxygen vacancies that charge the aliovalent direct substitution and Ce³⁺ formation. Heavy-ion irradiation at different fluences (1 × 10¹⁶ and 5 × 10¹⁶ ions per cm²) shows that the doped compositions offer improved resistance to radiation damage. These findings are attributed to the ballistic mixing of dopant-induced defects with those introduced by ionic implantation, thereby increasing defect recombination volume and enhancing lattice recovery. Furthermore, the defect migration and annealing mechanisms are seen to differ for the studied fluences, highlighting the specific role of sample surfaces as effective annealing sites.