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Sökning: id:"swepub:oai:DiVA.org:kth-336857" > Monitoring the grad...

LIBRIS Formathandbok  (Information om MARC21)
FältnamnIndikatorerMetadata
00003775naa a2200433 4500
001oai:DiVA.org:kth-336857
003SwePub
008230926s2022 | |||||||||||000 ||eng|
024a https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3368572 URI
024a https://doi.org/10.1016/j.jnucmat.2021.1535042 DOI
040 a (SwePub)kth
041 a engb eng
042 9 SwePub
072 7a ref2 swepub-contenttype
072 7a art2 swepub-publicationtype
100a El Jamal, Ghadau KTH,Tillämpad fysikalisk kemi4 aut0 (Swepub:kth)u1t150cr
2451 0a Monitoring the gradual change in oxidation state during surface oxidation or reduction of uranium oxides by photoemission spectroscopy of the 5f states
264 1b Elsevier BV,c 2022
338 a print2 rdacarrier
500 a QC 20230926
520 a Photoelectron spectroscopy study of the U5f emission gives valuable insight into the surface oxidation mechanism of uranium oxides. Its intensity is directly related to the electron count n(f), which decreases with increasing oxidation number (U(IV): n(f)= 2; U(V): n(f) = 1; U(VI): n(f)= 0). n5f can be quantified by analysing the U5f/U4f intensity ratio and using a standard of known composition. In addition, the 5f emission has a characteristic multiplet shape, directly related to n5f, which can be used to distinguish the 5f 2 and 5f 1 configuration of U(IV) and U(V), respectively. Three independent methods are used to determine the surface oxidation state: the U5f/U4f intensity ratio, the relative intensities of the U4f oxide shifted peaks, and the O1s/U4f intensity ratio. The first two reveal the concentration of the U in each oxide, the third indicates the total concentration of oxygen. These methods are applied to follow the surface modification of UO2 films when exposed to various oxidative conditions: molecular and atomic oxygen and water plasma at 400 C. In addition, the reduction of UO3 by atomic H is studied. Molecular oxygen oxidizes UO2 to UO2 +x(x = 0.22), containing both U(IV) and U(V). Atomic oxygen also oxidizes U(IV) to U(V) at low dosages, but then continues oxidizing U(V) to U(VI) (UO3) at high dosages. Conversely, atomic hydrogen reduces UO3. In the early phase of reduction U(V) forms exclusively - no U(IV) is observed. Water plasma first transforms almost all UO2 (surface and subsurface) into U(V). With further plasma exposure the surface is oxidized to about 80% U(VI) and 20% U(V). Up to this point, a small fraction of U(IV) remains at the surface. Once it disappears, the surface oxidation stops and further water plasma exposure now leads to surface reduction into U(V) (the 5f 1 peak increases again). Despite the reduction at high dosage, the O1s/U4f intensity ratio keeps increasing.
650 7a NATURVETENSKAPx Kemi0 (SwePub)1042 hsv//swe
650 7a NATURAL SCIENCESx Chemical Sciences0 (SwePub)1042 hsv//eng
653 a UO2
653 a Oxidation
653 a Reduction
653 a XPS-UPS
653 a Atomic oxygen
653 a hydrogen
653 a Quantification methods
700a Gouder, Thomasu European Commiss, Joint Res Ctr JRC, Karlsruhe, Germany.4 aut
700a Eloirdi, Rachelu European Commiss, Joint Res Ctr JRC, Karlsruhe, Germany.4 aut
700a Jonsson, Mats,d 1967-u KTH,Tillämpad fysikalisk kemi4 aut0 (Swepub:kth)u11mc94v
710a KTHb Tillämpad fysikalisk kemi4 org
773t Journal of Nuclear Materialsd : Elsevier BVg 560q 560x 0022-3115x 1873-4820
856u https://doi.org/10.1016/j.jnucmat.2021.153504y Fulltext
856u https://doi.org/10.1016/j.jnucmat.2021.153504
8564 8u https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-336857
8564 8u https://doi.org/10.1016/j.jnucmat.2021.153504

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El Jamal, Ghada
Gouder, Thomas
Eloirdi, Rachel
Jonsson, Mats, 1 ...
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