Local order around tungsten atoms in tungstate fluorophosphate glasses by X-ray absorption spectroscopy

Poirier, Gaël; Cassanjes, Fábia Castro; Messaddeq, Younès; Ribeiro, Sidney J. L.; Michalowicz, Alain; Poulain, Marcel

doi:10.1016/j.jnoncrysol.2005.08.038

Cited by 36 publications

(43 citation statements)

References 22 publications

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“…[86][87][88][89]91,92 The similarity of the post-edge XANES spectra in the as-synthesized compounds also indicates that second and further coordination shells are quite similar.…”

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 68%

“…[86][87][88][89] The intensity of pre-edge peak, indicated in Fig. 2(a) as X, is very sensitive to symmetry of the W atoms.…”

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 99%

“…2(a) as X, is very sensitive to symmetry of the W atoms. [87][88][89][90] According to the literature, [87][88][89][90] the preedge peak is due to electronic transitions from 2s to 5d (W) orbital, which is dipole forbidden in the case of regular octahedra but allowed for distorted octahedra and tetrahedral. The WO 3 (reference compound) exhibit small preedge peaks due to distorted octahedral [WO 6 ] clusters [inset in Fig.…”

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 99%

“…3(a)], in good agreement with previous reports. [87][88][89] In contrast, the as-synthesized samples (CaWO 4 ) exhibit a more intense pre-edge peak relate to tetrahedral [WO 4 ] clusters [inset in Fig. 3(a)], indicating that tungsten atoms are coordinated by four oxygen atoms.…”

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 99%

“…3(a)], indicating that tungsten atoms are coordinated by four oxygen atoms. [86][87][88][89] The higher intensity of the preedge peak of CaWO 4 crystals indicates a higher symmetry of W sites when compared to WO 3 compound. As can also be observed on Fig.…”

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 99%

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Presence of excited electronic state in CaWO4 crystals provoked by a tetrahedral distortion: An experimental and theoretical investigation

Gracia

Longo

Cavalcante

et al. 2011

Journal of Applied Physics

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By combining experimental techniques such as x-ray diffraction, Fourier transform Raman, ultraviolet-visible, x-ray absorption near edge structure, extended x-ray absorption fine structure spectroscopy, and theoretical models, a general approach to understand the relationship among photoluminescence (PL) emissions and excited electronic states in CaWO 4 crystals is presented. First-principles calculations of model systems point out that the presence of stable electronic excited states (singlet) allow us to propose one specific way in which PL behavior can be achieved. In light of this result, we reexamine prior experiments on PL emissions of CaWO 4 .

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“…[86][87][88][89]91,92 The similarity of the post-edge XANES spectra in the as-synthesized compounds also indicates that second and further coordination shells are quite similar.…”

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 68%

“…[86][87][88][89] The intensity of pre-edge peak, indicated in Fig. 2(a) as X, is very sensitive to symmetry of the W atoms.…”

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 99%

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 99%

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 99%

Section: B Xanes and Exafs Spectra Analysesmentioning

confidence: 99%

See 3 more Smart Citations

Presence of excited electronic state in CaWO4 crystals provoked by a tetrahedral distortion: An experimental and theoretical investigation

Gracia

Longo

Cavalcante

et al. 2011

Journal of Applied Physics

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EXAFS analysis of blue luminescence in polyoxytungstate citrate gels

Buysser¹,

Driessche²,

Vermeir³

et al. 2008

Physica Status Solidi (b)

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Remarkable color changes can be seen when ammonium metatungstate – citric acid gels are submitted to sunlight. The colors strongly depend of the pH values of the precursor solution. Luminescence measurements reveal that gels at pH 7 exhibit a strong blue emission resulting from the presences of WO42– tetrahedra while a slight green emission is due to WO66– octahedra. The shift in equilibrium from octahedral to tetrahedral coordination upon increase in pH is confirmed by detailed EXAFS analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Effect of different strontium precursors on the growth process and optical properties of SrWO4 microcrystals

et al. 2015

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In this paper, an experimental study was performed on the effect induced by different strontium precursors in the growth processes and optical properties of strontium tungstate (SrWO 4) microcrystals synthesized by the co-precipitation method. The structural behavior was analyzed by means of X-ray diffractions, Rietveld refinements, Fourier transform (FT)-Raman, and FT-infrared spectroscopies. X-ray absorption near-edge structure spectra performed at the W-L 1 and L 3 edges revealed the first coordination shell around the tungsten atoms is composed of four oxygens, i.e., existence of tetrahedral [WO 4 ] clusters inside the SrWO 4 structure. Field emission scanning electron microscopy (FE-SEM) images showed the presence of pitch and longleaf pine cone-like SrWO 4 microcrystals for most of the strontium precursors employed in the synthesis. Based on these FE-SEM images, a hypothetical crystal growth mechanism was proposed to explain the origin of these microcrystals. The optical properties were investigated by ultraviolet-visible spectroscopy and photoluminescence (PL) measurements at room temperature. The different optical band gap values found for this material, depending on the type of strontium precursor, were correlated with the existence of intermediary energy levels within the forbidden region. Finally, PL profiles were associated to the degree of distortions in tetrahedral [WO 4 ] clusters.

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Local order around tungsten atoms in tungstate fluorophosphate glasses by X-ray absorption spectroscopy

Cited by 36 publications

References 22 publications

Presence of excited electronic state in CaWO4 crystals provoked by a tetrahedral distortion: An experimental and theoretical investigation

Presence of excited electronic state in CaWO4 crystals provoked by a tetrahedral distortion: An experimental and theoretical investigation

EXAFS analysis of blue luminescence in polyoxytungstate citrate gels

Effect of different strontium precursors on the growth process and optical properties of SrWO4 microcrystals

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