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 properties under extreme conditions is of great significance for developing irradiation-resistant materials. Herein, a novel irradiation-resistant high-entropy fluorite oxide (Nd 0.2 Sm 0.2 Gd 0.2 Dy 0.2 Er 0.2 ) 2 Ce 2 O 7 is reported. After 9-MeV Au ion irradiation with ion fluence of 2.7 × 10 15 and 4.5 × 10 15 ions/cm 2 , the high-entropy (Nd 0.2 Sm 0.2 Gd 0.2 Dy 0.2 Er 0.2 ) 2 Ce 2 O 7 shows excellent phase stability without phase decomposition and transformation. In comparison with Nd 2 Ce 2 O 7 , the high-entropy (Nd 0.2 Sm 0.2 Gd 0.2 Dy 0.2 Er 0.2 ) 2 Ce 2 O 7 possesses much less amorphization and lattice expansion, suggesting its improved irradiation resistance. No pronounced variation in Raman spectra can be detected in the post-irradiated structure, implying rarely structural shift arises in high-entropy (Nd 0.2 Sm 0.2 Gd 0.2 Dy 0.2 Er 0.2 ) 2 Ce 2 O 7 . After irradiation, there is no irradiation-induced segregation at grain boundaries or inside the grains of high-entropy (Nd 0.2 Sm 0.2 Gd 0.2 Dy 0.2 Er 0.2 ) 2 Ce 2 O 7 . 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.