Ion-irradiation induced reduction in Sr2Fe1.5Mo0.5O6−δ perovskite

The incorporation of radioactive elements in fission products (FPs) into complex oxides, where the elements are constrained in the structure and enhanced leaching and radioactive stability can be obtained, is an active research area in the nuclear fuel cycle. Perovskite structured Sr2Fe1.5Mo0.5O6−δ (SFM) has the capability of incorporating several FPs (such as Sr and Mo) into the crystalline network simultaneously while maintaining a stabilized structure. The radiation damage effects on the structure changes of this polycrystalline SFM sample is conducted under various ion irradiations including 200 keV He ions to a fluence of 5 × 1020 ions m−2, 100 keV H to a fluence of 3 × 1021 ions cm−2, and 600 keV Kr ions to a fluence of 2.5 × 1019 ions m−2 at room temperature. Irradiation-induced structural evolution was examined by using grazing incidence X-ray diffraction and cross-sectional transmission electron microscopy. It was found that the irradiated SFM sample decomposed into a layered Sr4FeMoO8−δ based phase and a metallic Fe based phase under light ion (He and H) irradiations. Nano-crystallized secondary phase was observed with particle sizes around 7 nm. These results suggest that irradiation-induced reducing atmospheres may affect the stability of crystalline structure in complex oxides. Experiment results also reveal an amorphization in the heavy ion Kr irradiated sample, while no amorphization is observed in He/H irradiated SFM.