Characteristics of chemical bonding of pentavalent uranium in La-doped UO2
The effect of La doping on the electronic structure of U in UO2 was studied using an advanced technique, namely, X-ray absorption spectroscopy (XAS) in the high-energy-resolution fluorescence-detection (HERFD) mode, at the U 3d3/2 (M4) edge. Thanks to a significant reduction of the core–hole lifetime broadening and distinct chemical shifts of the HERFD-XAS lines, the U(V) formation as a result of La doping was identified. The isolated contribution of U(V) in the M4 HERFD-XAS spectrum reveals the so-called charge-transfer satellites due to the U 5f–O 2p hybridization. The analysis of the experimental data within the framework of the Anderson impurity model (AIM) indicates a significant change in the characteristics and degree of covalency for the chemical bonding in the U(V) subsystem of UO2 as compared to undoped UO2, which is a Mott–Hubbard system. The results are also supported by AIM calculations of X-ray photoelectron and optical absorption data.
BUTORIN S. M.;
KVASHNINA Kristina;
PRIEUR Damien;
RIVENET M.;
MARTIN Philippe;
2017-12-12
ROYAL SOC CHEMISTRY
JRC102459
1359-7345,
https://publications.jrc.ec.europa.eu/repository/handle/JRC102459,
10.1039/c6cc07684j,
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