Irradiation induced structural damage and evolution of mechanical properties in high entropy fluorite oxide

Pursuing material with excellent irradiation resistance, high chemical durability, and stable mechanical prop-erties under extreme conditions is of great significance for developing irradiation-resistant materials. Herein, a novel irradiation-resistant high-entropy fluorite oxide (Nd0.2Sm0.2Gd0.2Dy0.2Er0.2)2Ce2O7 is reported. After 9-MeV Au ion irradiation with ion fluence of 2.7 x 1015 and 4.5 x 1015 ions/cm2, the high-entropy (Nd0.2Sm0.2Gd0.2Dy0.2Er0.2)2Ce2O7 shows excellent phase stability without phase decomposition and trans-formation. In comparison with Nd2Ce2O7, the high-entropy (Nd0.2Sm0.2Gd0.2Dy0.2Er0.2)2Ce2O7 possesses much less amorphization and lattice expansion, suggesting its improved irradiation resistance. No pronounced varia-tion in Raman spectra can be detected in the post-irradiated structure, implying rarely structural shift arises in high-entropy (Nd0.2Sm0.2Gd0.2Dy0.2Er0.2)2Ce2O7. After irradiation, there is no irradiation-induced segregation at grain boundaries or inside the grains of high-entropy (Nd0.2Sm0.2Gd0.2Dy0.2Er0.2)2Ce2O7. The nanoindentation tests reveal that the mechanical properties of the high-entropy fluorite oxide rarely degrade. The results, along with the insight into the mechanism of heavy-ion irradiation resistance, provide insight for the subsequent research on the heavy-ion irradiation of high-entropy ceramics.