Neutron irradiation effect on site distribution of cations in non-stoichiometric magnesium aluminate spinel

Neutron irradiation effects on cation distribution in non-stoichiometric Mg–Al spinel were examined by ALCHEMI (Atom Location by Channeling Enhanced Microanalysis) method. Parameter n, or non-stoichiometry of MgO · nAl2O3 of the specimens, were n = 1.00, 1.01, 1.10, 1.48. These specimens were neutron-irradiated up to a fluence of 2.3 × 1024 n/m2 (E > 0.1 MeV) at 500–530 °C in JMTR. Some specimens contracted by the irradiation and the arrangement of cations became more disorder. The other specimens showed very small swelling by the irradiation and the cation distribution became slightly ordered. The cation distribution of the contracted specimen returned stepwise to the pre-irradiated condition after the annealing at 700 °C. The cation distribution of the slightly swollen specimens did not change after the annealing up to 700 °C. Cation distribution in the T-site was more sensitively influenced by the irradiation.