Chemical shift of Mn and Cr K-edges in X-ray absorption spectroscopy with synchrotron radiation

Joseph, D. Paul; Yadav, Ashok K.; Jha, S. N.; Bhattacharyya, D.

doi:10.1007/s12034-013-0567-8

Cited by 37 publications

(31 citation statements)

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“…The XANES spectra provide information about the coordination geometry, and charge states and are categorized by different features. These features are pre‐edge (transition from 1s to 3d bound state), [ 25,47,48,50 ] the main edge due to the transition of photoelectrons resonance from 1s to the continuum multiple scattering, [ 25,47,48,51–53 ] and the post‐edge above the main edge with the typical wiggles/oscillatory features, which provide information about the nearest neighbors and the local chemistry. [ 52 ] The CV curve (shown in Figure 3a) where, during the first discharge, the CV showed two broad peaks in between 1.5 and 0.9 V, which correspond to the intercalation of lithium into the MoTe 2 host lattice to form the Li x MoTe 2 structure.…”

Section: Resultsmentioning

confidence: 99%

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe₂ as Anode

Panda

Gangwar

Muthuraj

et al. 2020

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The major challenges faced by candidate electrode materials in lithium‐ion batteries (LIBs) include their low electronic and ionic conductivities. 2D van der Waals materials with good electronic conductivity and weak interlayer interaction have been intensively studied in the electrochemical processes involving ion migrations. In particular, molybdenum ditelluride (MoTe2) has emerged as a new material for energy storage applications. Though 2H‐MoTe2 with hexagonal semiconducting phase is expected to facilitate more efficient ion insertion/deinsertion than the monoclinic semi‐metallic phase, its application as an anode in LIB has been elusive. Here, 2H‐MoTe2, prepared by a solid‐state synthesis route, has been employed as an efficient anode with remarkable Li+ storage capacity. The as‐prepared 2H‐MoTe2 electrodes exhibit an initial specific capacity of 432 mAh g−1 and retain a high reversible specific capacity of 291 mAh g−1 after 260 cycles at 1.0 A g−1. Further, a full‐cell prototype is demonstrated by using 2H‐MoTe2 anode with lithium cobalt oxide cathode, showing a high energy density of 454 Wh kg−1 (based on the MoTe2 mass) and capacity retention of 80% over 100 cycles. Synchrotron‐based in situ X‐ray absorption near‐edge structures have revealed the unique lithium reaction pathway and storage mechanism, which is supported by density functional theory based calculations.

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Section: Resultsmentioning

confidence: 99%

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe₂ as Anode

Panda

Gangwar

Muthuraj

et al. 2020

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“…The strong absorption peak in the pre-edge region is generally attributed to a quadruple transition of a 1s electron to an empty antibonding 3d t 2g. (20) As shown in a decomposed plot of the calculated XANES in the Inset of Fig. 3B, the pre-edge peak is primarily due to the contribution from Cr 6+ .…”

Section: +mentioning

confidence: 89%

Charge disproportionation and the pressure-induced insulator–metal transition in cubic perovskite PbCrO ₃

Cheng

Kweon

Larrégola³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The perovskite PbCrO 3 is an antiferromagnetic insulator. However, the fundamental interactions leading to the insulating state in this single-valent perovskite are unclear. Moreover, the origin of the unprecedented volume drop observed at a modest pressure of P = 1.6 GPa remains an outstanding problem. We report a variety of in situ pressure measurements including electron transport properties, X-ray absorption spectrum, and crystal structure study by X-ray and neutron diffraction. These studies reveal key information leading to the elucidation of the physics behind the insulating state and the pressure-induced transition. We argue that a charge disproportionation 3Cr 4+ → 2Cr 3+ + Cr 6+ in association with the 6s-p hybridization on the Pb 2+ is responsible for the insulating ground state of PbCrO 3 at ambient pressure and the charge disproportionation phase is suppressed under pressure to give rise to a metallic phase at high pressure. The model is well supported by density function theory plus the correlation energy U (DFT+U) calculations. Fermi energy in a partially filled band system to give rise to a Mott insulator without changing the translation symmetry (1). However, how to justify the insulating ground state in the cubic perovskite PbCrO 3 with a 2/3-filled band remains controversial (2-11). An unphysically large U needs to be used in the density function theory (DFT) calculation (10) to open a gap, indicating that electron-electron correlations alone is insufficient to account for the insulator phase. More surprisingly, the structure undergoes a first-order transition at P = 1.6 GPa to another cubic phase with an extremely large volume drop (6). To clarify the fundamental interactions leading to the cubic insulating state and whether the pressure-induced volume collapse is accompanied with an insulator-metal transition, we carried out a suite of high-pressure experiments including structural characterization, measurements of resistivity, and X-ray absorption near edge structure (XANES) under high pressure and performed DFT with Hubbard U correction (DFT+U) calculations. Detailed information about the experiments, the DFT calculation, and the simulation for XANES is provided in SI Text.The PbCrO 3 perovskite was known to be stabilized under high pressure and high temperature (HPHT) in the 1960s (2). Structural studies by X-ray and neutron diffraction revealed that it crystallizes as a cubic Pm-3m perovskite with a lattice constant of a 0 ∼ 4.00 Å and exhibits a type G antiferromagnetic (AFM) order below T N = 240 K in contrast to the type C AFM order of CaCrO 3 below T N = 90 K and that of the tetragonal phase of SrCrO 3 . The magnetic moment on Cr 4+ as refined from neutron diffraction is 1.9 μ B , which is very close to the spin-only moment of 2 μ B expected for localized d 2 electrons. In comparison with other Cr 4+ -containing perovskites, ACrO 3 (A = Ca, Sr) (9, 12), PbCrO 3 exhibits peculiar structural and physical properties. The unit-cell volume V 0 of PbCrO 3 is significantly larger than expec...

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“…As has been discussed in the 'Introduction' section, the above edge shift (ΔE) values depend on the chemical environment of the absorbing species in the compound. It has also been shown by various authors (Nigam and Gupta 1974;Kondawar and Mande 1976;Ballal and Mande 1977;Apte and Mande 1981;Chetal et al 1988;Pandey et al 1990;Hinge et al 2011;Joseph et al 2012Joseph et al , 2013) that the effect of chemical environment can quantitatively be presented by 'effective charge' (q). Formation of chemical bond in a compound involves redistribution of valence electrons of the constituent atoms and effective charge is a hypothetical parameter which gives a measure of the charge residing over the cation, when it forms a bond with a ligand.…”

Section: Resultsmentioning

confidence: 90%

Chemical shift of U L3 edges in different uranium compounds obtained by X-ray absorption spectroscopy with synchrotron radiation

et al. 2014

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Uranium L 3 X-ray absorption edge was measured in various compounds containing uranium in U 4+ , U 5+ and U 6+ oxidation states. The measurements have been carried out at the Energy Dispersive EXAFS beamline (BL-08) at INDUS-2 synchrotron radiation source at RRCAT, Indore. Energy shifts of ~ 2-3 eV were observed for U L 3 edge in the U-compounds compared to their value in elemental U. The different chemical shifts observed for the compounds having the same oxidation state of the cation but different anions or ligands show the effect of different chemical environments surrounding the cations in determining their X-ray absorption edges in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on U cation in the above compounds.

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Chemical shift of Mn and Cr K-edges in X-ray absorption spectroscopy with synchrotron radiation

Cited by 37 publications

References 21 publications

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe₂ as Anode

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe₂ as Anode

Charge disproportionation and the pressure-induced insulator–metal transition in cubic perovskite PbCrO ₃

Chemical shift of U L3 edges in different uranium compounds obtained by X-ray absorption spectroscopy with synchrotron radiation

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Chemical shift of Mn and Cr K-edges in X-ray absorption spectroscopy with synchrotron radiation

Cited by 37 publications

References 21 publications

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe2 as Anode

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe2 as Anode

Charge disproportionation and the pressure-induced insulator–metal transition in cubic perovskite PbCrO 3

Chemical shift of U L3 edges in different uranium compounds obtained by X-ray absorption spectroscopy with synchrotron radiation

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High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe₂ as Anode

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe₂ as Anode

Charge disproportionation and the pressure-induced insulator–metal transition in cubic perovskite PbCrO ₃