Begaudeau, K., Morizet, Y., Florian, P., Paris, M. & Mercier, J.-C. (2012) Solid-state NMR analysis of Fe-bearing minerals: implications and applications for Earth sciences. Eur. J. Mineral. 24 535–550.
Added by: Laurent Cournède (2016-03-10 21:28:39)
|Type de référence: Article
Numéro d'identification (ISBN etc.): 0935-1221
Clé BibTeX: Begaudeau2012
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Mots-clés: alkali-silicate-glasses, aluminosilicate glasses, Fe-bearing minerals, ferromagnetic particles, h-1 mas nmr, hydrogen incorporation, mantle minerals, nominally anhydrous minerals, nuclear-magnetic-resonance, ortho-pyroxene, paramagnetic elements, peridotite xenoliths, pyroxene, resolution si-29 nmr, solid-state NMR
Créateurs: Begaudeau, Florian, Mercier, Morizet, Paris
Collection: Eur. J. Mineral.
Consultations : 7/413
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Solid-state nuclear magnetic resonance (NMR) is commonly used in the study of solid structures in Earth sciences; however, it suffers from the impossibility to analyse solid structures containing ferromagnetic particles or paramagnetic elements. We have attempted to decipher the effect of (1) ferromagnetic particles (Fe- Ti-bearing mineral phase) and (2) paramagnetic elements (Fe, Cr, Ni) on the signature of diamagnetic elements (H-1, Si-29, Al-27) in natural clino- and orthopyroxene from peridotite. The results obtained on these natural minerals have been compared with results obtained for a synthetic mixture of kaolinite + magnetite. The Si-29, Al-27 Echo-MAS NMR spectra acquired for pyroxenes show signatures that are consistent with previous data. Weak additional anomalous peaks are detected in Si-29 spectra. Both elements show a broadening in the spectra, which is commonly observed when paramagnetic elements are present. The perturbations induced by paramagnetic elements are the result of several interactions: (1) pseudocontact shift and (2) Fermi contact shift. H-1 Echo-MAS NMR spectra for pyroxenes are dramatically affected by the presence of ferromagnetic impurities and are chemical shifted beyond the known range for H-1 in solids. The effect of ferromagnetic particles is also confirmed by the results obtained for the kaolinite + magnetite mixture showing increasing perturbation with increasing magnetite content. We suggest that the presence of paramagnetic elements and/or ferromagnetic particles is only weakly affecting the Si-29 and Al-27 NMR spectra. Thus, new perspectives on the use of NMR technique for mineralogy and geochemistry are envisaged.
Added by: Laurent Cournède