He2+ irradiation response of structural evolution at different depths of MgO-Nd2(Zr1-xCex)2O7 composite ceramics used for inert matrix fuel

This paper reported the irradiation response of a 55 wt.% MgO-45 wt.% Nd 2 (Zr 1- x Ce x ) 2 O 7 (abbreviated to M-NZC x , x  = 0, 0.3 and 1) composite ceramics used as candidate inert matrix fuel under 500 keV He 2+ ions with fluence of 1 × 10 16 –5 × 10 17 ions/cm 2 . The irradiation-induced lattice expansion, amorphization of MgO and NZC x phases and order-disorder transition of Nd 2 (Zr 1- x Ce x ) 2 O 7 pyrochlore were systemically explored via GIXRD, Raman and TEM techniques. And the detailed irradiation response at different depths of the typical M-NZC 0.3 sample was especially investigated via GIXRD and TEM. The results showed that the lattice expansion ratios ( Rs ) of MgO (M), ordered pyrochlore (P) and disordered defect-fluorite (F) structures of NZC x pyrochlore in the samples under the same dose of He 2+ irradiation were regular, which were ranged as the following order: Rs M  <  Rs P  <  Rs F . And there was a belt-shaped damage aggregation zone located near interphase boundary at the maximum damage depth of M-NZC 0.3 sample, which could be explained by the defect-absorption of boundary. And this defect-absorption of boundary was also found at any depth of M-NZC 0.3 sample. This work systematically analyzed α-decay irradiation response of different phases in M-NZC x composite ceramics applying for inert matrix fuel.