Study on the relation between the crystal structure and thermal stability of FeUO4 and CrUO4

Application of High-Energy-Resolution X-ray Absorption Spectroscopy at the U L3-Edge to Assess the U(V) Electronic Structure in FeUO4

“…19 The FeUO 4 sample that we used in HERFD-XANES measurements was already characterized in previous literature. 14,16 X-ray diffraction profile of the FeUO 4 sample is shown in Figure S1. Fe species in FeUO 4 were evaluated to be trivalent by Fe K-edge XANES spectroscopy and 57 Fe Mossbauer spectroscopy.…”

“…Furthermore, Akiyama et al reported that FeUO 4 could be generated under the Fukushima Dai-ichi Nuclear Power Station’s severe accident conditions . Few studies exist on the electronic structure of FeUO 4 . ,− Guo et al reported that all U ions in FeUO 4 would be a 5+ oxidation state by DFT+U calculations (DFT = density functional theory), whereas the U 5+ /U ratio in FeUO 4 is 66.4%, as determined by X-ray photoelectron spectroscopy analysis in the U 4f region . Because of the possibility of surface oxidation, the U 5+ /U ratio does not represent the U valence information for the bulk samples.…”

“… 14 Few studies exist on the electronic structure of FeUO 4 . 7 , 14 − 16 Guo et al reported that all U ions in FeUO 4 would be a 5+ oxidation state by DFT+U calculations (DFT = density functional theory), whereas the U 5+ /U ratio in FeUO 4 is 66.4%, as determined by X-ray photoelectron spectroscopy analysis in the U 4f region. 15 Because of the possibility of surface oxidation, the U 5+ /U ratio does not represent the U valence information for the bulk samples.…”