Electronic structure and fine structural features of the air-grown UNxOy on nitrogen-rich uranium nitride

Abstract Oxide formation on surface of nitrogen-rich uranium nitride film/particles was investigated using X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), aberration-corrected transmission electron microscopy (TEM), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) coupled with electron energy-loss spectroscopy (EELS). XPS and AES studies indicated that the oxidized layer on UN 2-x film is ternary compound uranium oxynitride (UN x O y ) in 5–10 nm thickness. TEM/HAADF-STEM and EELS studies revealed the UN x O y crystallizes in the FCC CaF 2 -type structure with the lattice parameter close to the CaF 2 -type UN 2-x matrix. The work can provide further information to the oxidation mechanism of uranium nitride.