13-18 May 2018
Casino Conference Centre
Europe/Prague timezone

The XPS structure and the peculiarities of the chemical bond nature in CeO2

15 May 2018, 17:15
1h 30m
Gallery (Casino Conference Centre)

Gallery

Casino Conference Centre

Reitenbergerova 4/95, Mariánské Lázně, Czech Republic
Poster Radiation Chemistry Poster RCH

Speaker

Artem Mitrofanov (Moscow State University)

Description

Cerium dioxide is known as a non-radioactive structural substitute of actinide oxides (UO2 and PuO2). CeO2-based ceramics is suggested as an inert 239Pu or 235U bearing matrix for nuclear fuel, as well as a matrix for high-level waste disposal. CeO2 is also used an exhaust gas afterburning catalysts and in electronics.
X-ray photoelectron spectral structure of CeO2 valence electrons in the binding energy range 0−~50 eV was analyzed. The core-electron spectral structure parameters and relativistic discrete-variational calculation results for the CeO812- (D4h) cluster reflecting cerium close environment were taken into account. Comparison of the valence and the core-electron spectral structures showed that formation of the inner (IVMO) and the outer (OVMO) valence molecular orbitals contributes to the spectral structure more than the many-body processes. The Ce 4f electrons were established to participate directly in the chemical bond formation in CeO2 loosing partially their f nature. They were found to be localized mostly within the outer valence band. The Ce 5p atomic orbitals were shown to participate in the formation of both the inner and the outer valence molecular orbitals. A most of part in the IVMO formation is taken by the filled Ce 5p1/2,3/2 and O 2s atomic shells, while the Ce 5s electrons participate weakly in the chemical bond formation. The composition and the sequent order of the molecular orbitals in the binding energy range 0−~50 eV was established. A quantitative scheme of the molecular orbitals for CeO2 was built. This scheme is fundamental also for the interpretation of other X-ray spectra of CeO2. Evaluations yielded that the IVMO electrons weaken by 37 % the chemical bond formed by the OVMO electrons.
The work was supported by the RFBR grant № 17-03-00277a.

Primary authors

Konstantin Maslakov (Lomonosov Moscow State University) Dr Yury Teterin (Lomonosov Moscow State University/NRC “Kurchatov Institute”) Mikhail Ryzhkov (Institute of Solid State Chemistry, Ural Department of RAS) Alexej Popel (University of Cambridge) Anton Teterin (NRC “Kurchatov Institute”) Kirill Ivanov (NRC “Kurchatov Institute”) Artem Mitrofanov (Moscow State University) Prof. Stepan Kalmykov (Moscow State University) Vladimir Petrov (Lomonosov Moscow State University) Peter Petrov (Department of Materials and London Centre for Nanotechnology, Imperial College London) Ian Farnan (University of Cambridge)

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