Behaviour of niobium during early Earth's differentiation: insights from its local structure and oxidation state in silicate melts at high pressure
| Autor: | Z. Konopkova, R. Torchio, Hanns-Peter Liermann, C. de Grouchy, Konstantin Glazyrin, Innokenty Kantor, Olivier Mathon, Chrystèle Sanloup, B. Cochain, Tetsuo Irifune |
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| Přispěvatelé: | Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Edinburgh, Bavarian Research Institute of Experimental Geochemistry and Geophysics (Bayerisches Geoinstitut), Universität Bayreuth, European Synchrotron Radiation Facility (ESRF), Ehime University [Matsuyama], Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Ehime University [Matsuyama, Japon] |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Materials science
010504 meteorology & atmospheric sciences Absorption spectroscopy Coordination number Tantalum Analytical chemistry Niobium chemistry.chemical_element 010502 geochemistry & geophysics 01 natural sciences chemistry.chemical_compound Oxidation state niobium coordination number General Materials Science ddc:530 0105 earth and related environmental sciences X-ray absorption spectroscopy Valence (chemistry) magmas Condensed Matter Physics Silicate high pressure chemistry 13. Climate action Niobium valence [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy |
| Zdroj: | Journal of Physics: Condensed Matter Journal of Physics: Condensed Matter, IOP Publishing, 2018, Frontiers of High Pressure Physics, 30 (8), ⟨10.1088/1361-648X/aaa73e⟩ Journal of physics / Condensed matter 30(8), 084004-(2018). doi:10.1088/1361-648X/aaa73e Journal of Physics: Condensed Matter, 2018, Frontiers of High Pressure Physics, 30 (8), ⟨10.1088/1361-648X/aaa73e⟩ |
| ISSN: | 0953-8984 1361-648X |
| DOI: | 10.1088/1361-648X/aaa73e⟩ |
| Popis: | International audience; Niobium (Nb) is one of the key trace elements used to understand Earth's formation and differentiation, and is remarkable for its deficiency relative to tantalum in terrestrial rocks compared to the building chondritic blocks. In this context, the local environment of Nb in silica-rich melts and glasses is studied by in situ X-ray absorption spectroscopy (XAS) at high pressure (P) up to 9.3 GPa and 1350 K using resistive-heating diamond-anvil cells. Nb is slightly less oxidized in the melt (intermediate valence between +4 and +5) than in the glass (+5), an effect evidenced from the shift of the Nb-edge towards lower energies. Changes in the pre-edge features are also observed between melt and glass states, consistently with the observed changes in oxidation state although likely enhanced by temperature (T) effects. The oxidation state of Nb is not affected by pressure neither in the molten nor glassy states, and remains constant in the investigated P-range. The Nb-O coordination number is constant and equal to 6.3 ± 0.4 below 5 GPa, and only progressively increases up to 7.1 ± 0.4 at 9.3 GPa, the maximum P investigated. If these findings were to similarly apply to basaltic melts, that would rule out the hypothesis of Nb/Ta fractionation during early silicate Earth's differentiation, thus reinforcing the alternative hypothesis of fractionation during core formation on reduced pre-planetary bodies. |
| Databáze: | OpenAIRE |
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