u2o5-film-preparation-via-uo2-deposition-direct-current-sputtering

U2O5 Film Preparation via UO2 Deposition by Direct Current Sputtering and Successive Oxidation and Reduction with Atomic Oxygen and Atomic Hydrogen

We describe a method to produce U2O5 films in situ using the Labstation, a modular machine developed at JRC Karlsruhe. The Labstation, an essential part ...

Directorate for Nuclear Safety and Security

Thin films of the elusive intermediate uranium oxide UO have been prepared by exposing UO precursor multilayers to atomic hydrogen. Electron photoemission spectra measured about the uranium 4f core-level doublet contain sharp satellites separated by 7.9(1) eV from the 4f main lines, whilst satellites characteristics of the U(IV) and U(VI) oxidation states, expected respectively at 6.9(1) and 9.7(1) eV from the main 4f lines, are absent. This shows that uranium ions in the films are in a pure pentavalent oxidation state, in contrast to previous investigations of binary oxides claiming that U(V) occurs only as a metastable intermediate state coexisting with U(IV) and U(VI) species. The ratio between the 5f valence band and 4f core-level uranium photoemission intensities decreases by about 50% from UO to UO, which is consistent with the 5f  (UO) and 5f  (UO) electronic configurations of the initial state. Our studies conclusively establish the stability of uranium pentoxide.

Direct observation of pure pentavalent uranium in UO thin films by high resolution photoemission spectroscopy.

The development of tailored targets for the production of radioactive isotopes represents an active field in nuclear research. Radioactive beams find applications in nuclear medicine, in astrophysics, matter physics and materials science. In this work, we study the use of graphene both as carbon source for UO carbothermal reduction to produce UC targets, and also as functional properties booster. At fixed composition, the UC target grain size, porosity and thermal conductivity represent the three main points that affect the target production efficiency. UC was synthesized using both graphite and graphene as the source of carbon and the target properties in terms of composition, grain size, porosity, thermal diffusivity and thermal conductivity were studied. The main output of this work is related to the remarkable enhancement achieved in thermal conductivity, which can profitably improve thermal dissipation during operational stages of UC targets.

Article	Year
Direct observation of pure pentavalent uranium in UO thin films by high resolution photoemission spectroscopy. Scientific reports\| PubMed ID: 29844333	2018
Morphological and functional effects of graphene on the synthesis of uranium carbide for isotopes production targets. Scientific reports\| PubMed ID: 29844395	2018

Rachel Eloirdi

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