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Título:
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Low-magnesium uranium-calcite with high degree of crystallinity and gigantic luminescence emission
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Autores:
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Valle Fuentes, Francisco José ;
García Guinea, Javier ;
Cremades Rodríguez, Ana Isabel ;
Correcher Delgado, Virgilio ;
Sánchez Moral, Sergio ;
Gon´zalez Martin, Rafael ;
Sánchez Muñoz, Luis ;
López Arce, Paula
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Tipo de documento:
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texto impreso
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Editorial:
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Pergamon-Elsevier Science Ldt, 2007-01
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Dimensiones:
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application/pdf
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Nota general:
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info:eu-repo/semantics/restrictedAccess
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Idiomas:
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Palabras clave:
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Estado = Publicado
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Materia = Ciencias: Física: Física de materiales
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Tipo = Artículo
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Resumen:
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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.
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En línea:
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https://eprints.ucm.es/id/eprint/23102/1/CremadesAna19.pdf
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