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

Abstract

This paper reported the irradiation response of a 55 wt.% MgO-45 wt.% Nd2(Zr1-xCex)2O7 (abbreviated to M-NZCx, x = 0, 0.3 and 1) composite ceramics used as candidate inert matrix fuel under 500 keV He2+ ions with fluence of 1 × 1016–5 × 1017 ions/cm2. The irradiation-induced lattice expansion, amorphization of MgO and NZCx phases and order-disorder transition of Nd2(Zr1-xCex)2O7 pyrochlore were systemically explored via GIXRD, Raman and TEM techniques. And the detailed irradiation response at different depths of the typical M-NZC0.3 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 NZCx pyrochlore in the samples under the same dose of He2+ irradiation were regular, which were ranged as the following order: RsM < RsP < RsF. And there was a belt-shaped damage aggregation zone located near interphase boundary at the maximum damage depth of M-NZC0.3 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-NZC0.3 sample. This work systematically analyzed α-decay irradiation response of different phases in M-NZCx composite ceramics applying for inert matrix fuel.