Kr10+ irradiation stability and strain accumulation of MgONd2(Zr1-xCex)2O7 composite ceramics for inert matrix fuel

Abstract

In this work, MgONd₂(Zr_1-xCe_x)₂O₇ (M-NZC_x) composite ceramics, a potential matrix, used for inert matrix fuel were subjected to 3.5 MeV Kr¹⁰⁺ irradiation with fluences of 1 × 10¹⁴–5 × 10¹⁵ ions/cm². The phase transition from pyrochlore (P) to defect fluorite (F) structures (P-F transition) in NZC_x phase, as well as the lattice expansion, amorphization and strain accumulation in both MgO and pyrochlore phases in post-irradiated M-NZC_x composite ceramics were systematically investigated. Specifically, the lattice expansion ratios (Rs) of different phases in M-NZC_x samples irradiated with the same fluence of Kr¹⁰⁺ ions were ranged as follows, Rs_M < Rs_P < Rs_F. The further research on irradiation response of different phases in typical M-NZC_0.3 sample indicated that MgO exhibited superior irradiation stability to pyrochlore phase. Additionally, the strain accumulation induced by Kr¹⁰⁺ bombardment was observed generally in both MgO and NZC_0.3 pyrochlore phases, and the defect-induced strain in MgO crystalline was more pronounced than NZC_0.3 pyrochlore phase. Interestingly, the strain accumulation resulting from Kr¹⁰⁺ irradiation was observed to be preferentially oriented along directions with lower atomic density. This study might provide a new perspective for understanding the irradiation stability of MgONd₂Zr₂O₇ based composite ceramics in elastic collision cascade by krypton ions.