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Oxidation state of uranium in metamict and annealed zircon: near-infrared spectroscopic quantitative analysis

dc.contributor.authorZhang, Mingen_US
dc.contributor.authorSalje, Ekhard K. H.en_US
dc.contributor.authorEwing, Rodney C.en_US
dc.date.accessioned2006-12-19T18:56:55Z
dc.date.available2006-12-19T18:56:55Z
dc.date.issued2003-05-28en_US
dc.identifier.citationZhang, Ming; Salje, Ekhard K H; Ewing, Rodney C (2003). "Oxidation state of uranium in metamict and annealed zircon: near-infrared spectroscopic quantitative analysis." Journal of Physics: Condensed Matter. 15(20): 3445-3470. <http://hdl.handle.net/2027.42/48889>en_US
dc.identifier.issn0953-8984en_US
dc.identifier.urihttps://hdl.handle.net/2027.42/48889
dc.description.abstractRadiation and thermally induced changes in the oxidation state of uranium in metamict zircon have been systematically analysed, for the first time, using polarized near-infrared spectroscopy. The results showed that in damaged zircon U ions in crystalline domains exhibited relatively sharp, anisotropic signals from tetravalent and pentavalent U ions in crystalline domains ( Ucrystal4+ and Ucrystal5+). The linewidths and peak positions of the 4834 cm−1 band (Ucrystal4+, E ∥ c) and the 6668 cm−1 band (Ucrystal5+, E ⊥ c) are a non-linear function of the self-radiation dose. They reach nearly constant values at doses greater than ∼ 3.5 × 1018 α-events g−1. Quantitative analysis of Ucrystal4+ and Ucrystal5+ signals revealed that the intensity ratio (Ucrystal4+ /U crystal5+) exhibited a nearly linear increase as a function of dose and decreased on heating. This suggests that radiation leads to an alteration of the oxidation states of U and the tetravalent state is more preferable in radiation-damaged zircons. U ions associated with amorphous materials (Uamorphous) gave rise to broad and isotropic signals and they were mainly in the tetravalent state (Uamorphous4+), although small amounts of pentavalent U ions (Uamorphous5+) may exist. The dose dependence of the intensity ratio of Uamorphous/Utotal did not follow that of the reported fraction of the amorphous domain, but gave clearly lower values. This implies the potential preferential occurrence of U ions or possible U enrichment in the crystalline regions. Annealing intermediately and highly damaged zircon had different impacts on the oxidation state of U. An intermediately damaged zircon (with a dose of ∼ 5.2 × 1018 α-events g−1), annealed at high temperatures between 500 and 1800 K, showed a systematic increase in the signals of Ucrystal4+ and Ucrystal5+ above 700 K while Ucrystal4+ bands disappeared at temperatures above 1600 K. In contrast, a highly damaged zircon (with a dose of ∼ 15.9 × 1018 α-events g−1) exhibited the presence of Ucrystal4+ and Ucrystal5+ above 1000 K, with a dramatic increase in signals near 1400 K.en_US
dc.format.extent3118 bytes
dc.format.extent840406 bytes
dc.format.mimetypetext/plain
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherIOP Publishing Ltden_US
dc.titleOxidation state of uranium in metamict and annealed zircon: near-infrared spectroscopic quantitative analysisen_US
dc.typeArticleen_US
dc.subject.hlbsecondlevelPhysicsen_US
dc.subject.hlbtoplevelScienceen_US
dc.description.peerreviewedPeer Revieweden_US
dc.contributor.affiliationumDepartment of Nuclear Engineering and Radiological Sciences, Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-2104, USAen_US
dc.contributor.affiliationotherDepartment of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UKen_US
dc.contributor.affiliationotherDepartment of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UKen_US
dc.contributor.affiliationumcampusAnn Arboren_US
dc.description.bitstreamurlhttp://deepblue.lib.umich.edu/bitstream/2027.42/48889/2/c32007.pdfen_US
dc.identifier.doihttp://dx.doi.org/10.1088/0953-8984/15/20/307en_US
dc.identifier.sourceJournal of Physics: Condensed Matter.en_US
dc.owningcollnameInterdisciplinary and Peer-Reviewed


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