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

Area of Science:

• Materials Science
• Solid State Chemistry
• Radiation Effects

Background:

• Ceria (CeO2) is a versatile material with applications in catalysis, solid oxide fuel cells, and radiation shielding.
• Understanding the impact of doping and irradiation on ceria's defect structure is crucial for optimizing its performance and durability.

Purpose of the Study:

• To investigate the effects of trivalent yttrium (Y) doping on the structural and radiation stability of ceria.
• To analyze the nature of oxygen vacancies and their role in charge compensation and defect formation.
• To evaluate the radiation resistance of Y-doped ceria under heavy-ion irradiation.

Main Methods:

• X-ray diffraction (XRD) for structural analysis and defect ordering.
• Raman spectroscopy and positron annihilation spectroscopy for characterizing oxygen vacancies.
• Heavy-ion irradiation experiments at varying fluences (1x10^16 and 5x10^16 ions/cm^2).

Main Results:

• Yttrium incorporation induces long-range ordering of anionic vacancies and formation of Y2O3 nanodomains within the fluorite structure.
• Spectroscopic analyses confirm aliovalent substitution and Ce3+ formation, linked to oxygen vacancy creation.
• Y-doped ceria exhibits enhanced resistance to radiation damage compared to undoped samples.
• Defect migration and annealing mechanisms are fluence-dependent, with sample surfaces acting as effective annealing sites.

Conclusions:

• Yttrium doping significantly improves the radiation stability of ceria by promoting defect ordering and enhancing lattice recovery.
• The observed radiation resistance is attributed to the synergistic effect of dopant-induced defects and irradiation-induced defects.
• Surface effects play a critical role in defect annealing processes under irradiation.