Niobium LIII and LII X-ray absorption-edge spectra of Nb2O5 and NH4NbF6

Sugiura, Chikara; Kitamura, Michihide; Muramatsu, Susumu

doi:10.1016/0022-3697(88)90159-x

Cited by 18 publications

(34 citation statements)

References 16 publications

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“…Double‐featured peaks (2372.95 eV at peak A and 2375.80 eV at peak B) are dominant in Figure , accompanied by a weak signal at approximately 2387.05 eV (peak C). The peaks at A and B are due to the 2p 3/2 →4d 5/2 transition, while the weak signal at C is attributed to the 2p 3/2 →5s transition . The observed double‐featured peaks at A and B originate from the ligand field splitting of d‐orbitals of Nb atom .…”

Section: Resultsmentioning

confidence: 92%

Enhanced Olefin Metathesis Performance of Tungsten and Niobium Incorporated Bimetallic Silicates: Evidence of Synergistic Effects

Ramanathan

Kersting³

et al. 2020

ChemCatChem

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Tungsten and niobium incorporated KIT‐6 (WNb‐KIT‐6) materials were synthesized by a one‐pot sol‐gel method. During 2‐butene+ethylene metathesis with these materials at 450 °C, the propene yield is maximized (∼70 %) at a certain metal composition (∼20 wt% W and ∼1 wt% Nb), significantly surpassing those reported with an industrial WO3/SiO2 catalyst. The enhanced propene yield is attributed to better dispersion of W species on the catalyst surface and the formation of new active site precursors (O=)2W(O−Si)(O−Nb), as confirmed by XRD, TEM, H2‐TPR, XPS, EXAFS, and ToF‐SIMS techniques. Complementary DFT calculations reveal a positive correlation between the O=W=O bond angle and the propene yield. We therefore speculate that the −O−Nb moiety tunes the electronic environment around the W atom and increases the propene yield.

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Section: Resultsmentioning

confidence: 92%

Enhanced Olefin Metathesis Performance of Tungsten and Niobium Incorporated Bimetallic Silicates: Evidence of Synergistic Effects

Ramanathan

Kersting³

et al. 2020

ChemCatChem

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“…The observed D‐E separation corresponds to the ligand‐field splitting of the 4d state of Nb 5+ . The following weak structure at around 2385 eV is the allowed transition to the empty molecular orbital Nb 5s with symmetry A 1g in Oh group …”

Section: Results On Phase Separation Investigationmentioning

confidence: 99%

“…The following weak structure at around 2385 eV is the allowed transition to the empty molecular orbital Nb 5s with symmetry A 1g in Oh group. 17 For LiNbO 3 , the local symmetry around Nb is C3v. In such a group, there are two processes: a C3 distortion of the octahedron coordination shell, and a symmetry lowering compared to a regular octahedron.…”

Section: Environment Around Nb In Irradiatedmentioning

confidence: 99%

Nanoscale Phase Separation in Lithium Niobium Silicate Glass by Femtosecond Laser Irradiation

et al. 2016

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International audienceUnderstanding the phase transformation in glass and the morphology of related nanostructure after femtosecond laser irradiation is of great importance for fabricating functional optics, in which glass crystallization is involved to obtain nonlinear optical properties. We report on the crystallization inside lithium niobium silicate glass induced by fs laser irradiation. Energy-dispersive X-ray spectroscopy coupled to scanning transmission electron microscopy (STEM/EDS) and transmission electron microscopy confirm a nanoscale phase separation whereby LiNbO3 crystals are embedded in lamella-shaped frames of amorphous SiO2. The obtained nanostructure may have applications in fabricating second-order nonlinear optical devices

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“…Compared with the situation as regards 3d TM L 2 and L 3 XAS spectra [28], both the experimental and theoretical study of 4d TM L 2;3 XAS spectra lag far behind. It is usually assumed that the 4d TM L 2;3 XAS spectra reflect directly the unoccupied 4d orbitals, and thus the spectra have often been interpreted in terms of crystal-field or molecular-orbital theories [29][30][31][32]. In the case of O h local symmetry, it is then expected that the intensity ratio of transitions into the crystal-fieldsplit t 2g and e g states Iðt 2g Þ=Iðe g Þ is 0.5 for Ru(IV) [4d 4 ] and increases to 0.75 for Ru(V) [4d 3 ] at both the L 2 and the L 3 edges.…”

Section: Ru L 2;3 Xas Spectramentioning

confidence: 99%

The distribution of the doped holes in La2−xSrxCu1−yRuyO4−δ

Golden

Ebbinghaus

et al. 2002

Chemical Physics

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We present a systematic study of the perovskite-related system La 2Àx Sr x Cu 1Ày Ru y O 4Àd using Cu L 2;3 ; Ru L 2;3 , and O K X-ray absorption spectroscopy (XAS), magnetic and electrical measurements. This system can be regarded as hole-doped via substitution of La by Sr and to be electron-doped via substitution of Ru by Cu, and thus the question as to the distribution of the charge carriers and the interaction between Cu and Ru ions are central to our understanding of these novel systems. The comparison of the experimental data with the crystal-field-multiplet calculations shows clearly that the charge balance for x=2y > 1 is predominantly achieved by an increase of the Ru valence from Ru(IV) to Ru(V), while Cu remains in the Cu(II) oxidation state. Ó

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Niobium LIII and LII X-ray absorption-edge spectra of Nb2O5 and NH4NbF6

Cited by 18 publications

References 16 publications

Enhanced Olefin Metathesis Performance of Tungsten and Niobium Incorporated Bimetallic Silicates: Evidence of Synergistic Effects

Enhanced Olefin Metathesis Performance of Tungsten and Niobium Incorporated Bimetallic Silicates: Evidence of Synergistic Effects

Nanoscale Phase Separation in Lithium Niobium Silicate Glass by Femtosecond Laser Irradiation

The distribution of the doped holes in La2−xSrxCu1−yRuyO4−δ

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