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Title: Mg K-Edge XANES Spectra in Crystals and Oxide Glasses: Experimental vs. Theoretical Approaches

Abstract

Experimental Mg K-edge XANES spectra were obtained for crystals and synthetic glasses. To interpret the experiments, two different ab initio XANES calculation methods were employed. The first one is based on multiple-scattering calculations and muffin-tin potentials (FEFF package). The second uses a plane-wave basis set, norm-conserving pseudo-potentials, periodic boundary conditions. The resulting calculations for reference models with three different Mg coordinations are used to derive the best way to analyze the experimental XANES spectra for the glasses.

Authors:
;  [1];  [2];  [1];  [3];  [4]; ;  [5]
  1. Laboratoire des Geomateriaux, Universite de Marne La Vallee, 5 bd Descartes 77454 Marne la Vallee (France)
  2. IMPMC, Universite Pierre et Marie Curie (Paris 6), Campus de Boucicaut, 140 rue de Lourmel, 75015 Paris (France)
  3. (USM 201), Museum National d'Histoire Naturelle, CNRS UMR 7160, 61 rue Buffon, 75005 Paris (France)
  4. (United States)
  5. CNRS UR1 Soleil, BP 48, 91192 Gif sur Yvette (France)
Publication Date:
OSTI Identifier:
21054600
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal Issue: 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644482; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTROSCOPY; BOUNDARY CONDITIONS; CALCULATION METHODS; COMPUTER CALCULATIONS; CRYSTAL STRUCTURE; CRYSTALS; GLASS; MAGNESIUM; MUFFIN-TIN POTENTIAL; MULTIPLE SCATTERING; OXIDES; PERIODICITY; WAVE PROPAGATION; X-RAY SPECTROSCOPY

Citation Formats

Trcera, Nicolas, Rossano, Stephanie, Cabaret, Delphine, Farges, Francois, Laboratoire de Mineralogie, Department of Geological and Environmental Sciences, Stanford University, Flank, Anne-Marie, and Lagarde, Pierre. Mg K-Edge XANES Spectra in Crystals and Oxide Glasses: Experimental vs. Theoretical Approaches. United States: N. p., 2007. Web. doi:10.1063/1.2644482.
Trcera, Nicolas, Rossano, Stephanie, Cabaret, Delphine, Farges, Francois, Laboratoire de Mineralogie, Department of Geological and Environmental Sciences, Stanford University, Flank, Anne-Marie, & Lagarde, Pierre. Mg K-Edge XANES Spectra in Crystals and Oxide Glasses: Experimental vs. Theoretical Approaches. United States. doi:10.1063/1.2644482.
Trcera, Nicolas, Rossano, Stephanie, Cabaret, Delphine, Farges, Francois, Laboratoire de Mineralogie, Department of Geological and Environmental Sciences, Stanford University, Flank, Anne-Marie, and Lagarde, Pierre. Fri . "Mg K-Edge XANES Spectra in Crystals and Oxide Glasses: Experimental vs. Theoretical Approaches". United States. doi:10.1063/1.2644482.
@article{osti_21054600,
title = {Mg K-Edge XANES Spectra in Crystals and Oxide Glasses: Experimental vs. Theoretical Approaches},
author = {Trcera, Nicolas and Rossano, Stephanie and Cabaret, Delphine and Farges, Francois and Laboratoire de Mineralogie and Department of Geological and Environmental Sciences, Stanford University and Flank, Anne-Marie and Lagarde, Pierre},
abstractNote = {Experimental Mg K-edge XANES spectra were obtained for crystals and synthetic glasses. To interpret the experiments, two different ab initio XANES calculation methods were employed. The first one is based on multiple-scattering calculations and muffin-tin potentials (FEFF package). The second uses a plane-wave basis set, norm-conserving pseudo-potentials, periodic boundary conditions. The resulting calculations for reference models with three different Mg coordinations are used to derive the best way to analyze the experimental XANES spectra for the glasses.},
doi = {10.1063/1.2644482},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}
  • Mn K edge ab initio FEFF8.2 calculations of the pre-edge features of the x-ray-absorption near-edge structure (XANES) region were undertaken for a series of Mn-bearing oxide-type compounds. The aim of the study is to provide a reliable method for determining quantitative and accurate redox and symmetry information for manganese. In agreement with multiplet calculations by Glatzel and co-workers, FEFF8.2 predicts a doublet and a triplet for Mn(II) and Mn(III) in octahedral symmetry, respectively, in agreement with high-resolution XANES experiments. Site distortion increases notably the contribution from dipolar transitions and, consequently, the pre-edge feature integrated area. An even more intense pre-edgemore » feature is calculated and measured for the T{sub d} symmetry (singletlike). For Mn(IV), a triplet is predicted and measured for the O{sub h} symmetry. However, additional transitions are found in Mn(IV)-rich compounds, that are related to metal-metal transitions. These transitions overlap strongly with the 'true pre-edge', making extraction of redox and symmetry information for Mn(IV) more challenging. However, a model of the pre-edge with pseudo-Voigt functions of fixed calculated width (based on core-hole lifetime and experimental resolution) helps to separate the contributions related to first-neighbor symmetry from those of the metal-metal pairs. Application to multivalent defective manganese oxide materials suggests that the pre-edge information varies linearly as a function of Mn redox state or symmetry but varies nonlinearly as a function of both parameters. Finally, the polymerization of the manganese networks can be estimated from the metal-metal transitions found in the pre-edge region.« less
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  • High-resolution B K-edge X-ray absorption near-edge structure (XANES) spectra of K{sub 2}O-SiO{sub 2}-B{sub 2}O{sub 3}-P{sub 2}O{sub 5} glasses are reported using synchrotron radiation. Two prominent features, peak a at about 194.0 eV and peak b at about 198.0 eV, are observed. In the basis of the qualitative MO diagrams of BO{sub 3}{sup 3{minus}} and BO{sub 4}{sup 5{minus}} clusters, peak a is assigned to the transition of B 1s electrons to the unoccupied B 2p{sub z} ({pi}*) states for threefold-coordinated B ({sup [3]}B), and peak b is assigned to the transition of B 1s electrons to the unoccupied B {sigma}* statesmore » for fourfold-coordinated B({sup [4]}B). B K-edge XANES spectroscopy is established as a method for {open_quotes}fingerprinting{close_quotes} {sup [3]}B and {sup [4]}B in borate and borosilicate minerals, glasses, and melts. Also, the relative proportions of {sup [4]}B and {sup [3]}B in the borosilicate glasses are determined from the integrated peak areas for {sup [3]}B and {sup [4]}B edge peaks and are shown to be generally in good agreement with recent {sup 11}B MAS NMR measurements. However, the surface and near-surface structure of powder particles of perboric glasses containing P{sub 2}O{sub 5} appears to have a lower proportion of {sup [3]}B entities than the bulk. 27 refs., 4 figs., 1 tab.« less
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