Response of structure and mechanical properties of high entropy pyrochlore to heavy ion irradiation

Material with superior damage tolerance, chemical durability, and structure stability is of increasing interest in high-level radioactive waste management and structural components for advanced nuclear systems. In this paper, high-entropy (La 0.2 Ce 0.2 Nd 0.2 Sm 0.2 Gd 0.2 ) 2 Zr 2 O 7 with pyrochlore-type structure was synthesized through conventional solid-state method. The as-synthesized high-entropy oxide maintained crystalline after being irradiated by using Au 3+ with 9.0 MeV energy at the fluence of 4.5 × 10 15 ions·cm -2 , indicating its high tolerance to heavy-ion irradiation. The irradiation-induced order-disorder transition from pyrochlore structure to defective fluorite structure occurred in high-entropy (La 0.2 Ce 0.2 Nd 0.2 Sm 0.2 Gd 0.2 ) 2 Zr 2 O 7 . After irradiation, no irradiation-induced segregation was observed at grain boundary. Moreover, the mechanical properties of high-entropy pyrochlore were improved. The heavy-ion irradiation resistance mechanisms of high-entropy pyrochlore were discussed in detail. Our work identified high-entropy (La 0.2 Ce 0.2 Nd 0.2 Sm 0.2 Gd 0.2 ) 2 Zr 2 O 7 can be a promising candidate for immobilization of high-level radioactive waste as well as advanced nuclear reactor system from the perspective of irradiation resistance.