Applications of near-infrared FT-Raman spectroscopy in metamict and annealed zircon: oxidation state of U ions |
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Authors: | Email author" target="_blank">M?ZhangEmail author E K H?Salje R C?Ewing P?Daniel T?Geisler |
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Institution: | (1) Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK;(2) Department of Nuclear Engineering and Radiological Sciences, Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-2104, USA;(3) Laboratoire de Physique de l Etat Condensé, UPRES A CNRS n°6087, Université du Maine – Faculté des Sciences, Av. Olivier Messiaen, 72085, Le MANS Cedex 9, France;(4) Mineralogisches Institut, Universität Münster, Corrensstr. 24, 48149 Münster, Germany |
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Abstract: | We report a near-infrared Fourier-transform (FT) Raman spectroscopic method to characterize the electronic transitions of U ions and the alpha-decay damage in natural zircon. The application is demonstrated by analyzing metamict and annealed zircons from Sri Lanka. The data from crystalline zircon reveal a relatively sharp spectral feature appearing near 2733 cm–1 in Stokes spectra with a laser excitation of 1064 nm. The feature is assigned as signals related to the previously reported U5+ absorption near 6668 cm–1. With increasing self-irradiation dose, the feature shows a systematic decrease in intensity, accompanied by a gradual development of a broad feature between 3000 and 3400 cm–1. On heating for 1 h, the U5+ feature shows an increase in intensity starting near ~700 K for partially metamict zircon, whereas for highly damaged zircon the first recovery of the feature takes place near 1000 K, accompanied by a decrease in the radiation-induced broad band. The changes observed in the present study reflect the variations of local environments of U ions in natural zircon during metamictization and thermal annealing. |
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Keywords: | Near infrared Raman spectroscopy Zircon Radiation damage Recrystallization |
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