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Valle Fuentes, Francisco José and García Guinea, Javier and Cremades Rodríguez, Ana Isabel and Correcher Delgado, Virgilio and Sánchez Moral, Sergio and Gon´zalez Martin, Rafael and Sánchez Muñoz, Luis and López Arce, Paula (2007) Low-magnesium uranium-calcite with high degree of crystallinity and gigantic luminescence emission. Applied Radiation and Isotopes, 65 (1). pp. 147-154. ISSN 0969-8043
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Official URL: http://www.sciencedirect.com/science/article/pii/S0969804306002983
Abstract
Cabrera (Madrid) low-Mg calcites exhibit: (i) an unusual twofold elevation in X-ray diffraction pattern intensity; (ii) a 60-fold elevation of luminescence emission, compared to six common natural calcites selected for comparison purposes; (iii) a natural relatively high radiation level of circa 200 nSv h^-1 not detected in 1300 other calcites from the Natural History Museum of Madrid. Calcites were analysed by the X-ray diffraction powder method (XRD), cathodo-luminescence spectroscopy in scanning electron microscopy (CL-SEM), thermoluminescence (TL), differential thermal analysis (DTA), X-ray fluorescence spectrometry (XRF) and particle size distribution (PSD). The Cabrera calcite study shows: (i) helicoidally distributed steps along the (0001) orientation; (ii) protuberance defects onto the (0001) surface, observed by SEM; (iii) XRF chemical contents of 0.03% MgO, 0.013% of Y_2O_3, and 0.022% of U_3O_8, with accessory amounts of rare earth elements (REE); (iv) DTA dissociation temperature of 879 degrees C; (v) TL maxima peaks at 233 and 297 degrees C whose areas are 60 times compared to other calcites; (vi) spectra CL-SEM bands at 2.0 and 3.4 eV in the classic structure of Mn^2+ activators; (vii) a twofold XRD pattern explained given that sample is a low-Mg calcite. The huge TL and CL emissions of the Cabrera calcite sample must be linked with the uranyl group presence. This intense XRD pattern in low-Mg calcites could bring into being analytical errors.
Item Type: | Article |
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Additional Information: | © 2006 Elsevier Ltd. All rights reserved. |
Uncontrolled Keywords: | X-Ray-Diffraction, Quantitative-Determination, Retrospective Dosimetry, Xrd Analysis, Quartz; Minerals, Thermoluminescence, Interface, Xafs |
Subjects: | Sciences > Physics > Materials |
ID Code: | 23102 |
Deposited On: | 15 Oct 2013 11:51 |
Last Modified: | 09 May 2016 14:30 |
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