Oxidation state and chemical shift investigation in transition metal oxides by EELS

Tan, Haiyan; Verbeeck, Johan; Abakumov, Artem M.; Tendeloo, Gustaaf Van

doi:10.1016/j.ultramic.2012.03.002

Cited by 491 publications

(534 citation statements)

References 89 publications

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“…6(a)] show Mn L 3 peak positions of 639.75 eV and 638.25 eV, respectively, i.e., a difference of 1.5 eV. Comparison with literature data 17 shows that this can be interpreted as a reduced valence state of Mn in the pillar. Applying the same procedure to the Mn spectrum image in Fig.…”

Section: Apl Mater 2 127301 (2014)mentioning

confidence: 65%

Materials News: Interfacial chemistry and atomic arrangement of ZrO2 − La2/3Sr1/3MnO3 pillar-matrix structures

et al. 2014

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We studied ZrO2 − La2/3Sr1/3MnO3 pillar–matrix thin films which were found to show anomalous magnetic and electron transport properties. With the application of an aberration-corrected transmission electron microscope, interfacial chemistry, and atomic-arrangement of the system, especially of the pillar–matrix interface were revealed at atomic resolution. Minor amounts of Zr were found to occupy Mn positions within the matrix. The Zr concentration reaches a minimum near the pillar–matrix interface accompanied by oxygen vacancies. La and Mn diffusion into the pillar was revealed at atomic resolution and a concomitant change of the Mn valence state was observed.

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Section: Apl Mater 2 127301 (2014)mentioning

confidence: 65%

Materials News: Interfacial chemistry and atomic arrangement of ZrO2 − La2/3Sr1/3MnO3 pillar-matrix structures

et al. 2014

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“…The primary oxidation state of V was in both samples the same, but the 10 mol % and the 25 mol % samples showed some differences with respect to the second oxidation state that was observed. Careful analysis of the energy loss at the peak onset, the shape of the fine structure, and comparison to data from other well established microscopy research groups 42,43 strongly suggest the majority of V to be present in a tetravalent state. In fact, Liivat and Thomas suggested the tetrahedral structure offering a stabilizing effect on VO 4 4-units.…”

Section: Phase Evolution and Powder Morphology Dependency On The V Comentioning

confidence: 89%

Vanadium Substitution in Li₂MnSiO₄/C as Positive Electrode for Li Ion Batteries

Wagner¹,

Vullum

Nord³

et al. 2016

J. Phys. Chem. C

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“…However, such a technique is strongly dependent on thickness and background extraction procedures and can impose difficulties when very small charge variations are studied. Other methods such as Mn-L3 or O-K onset energies, energy differences between the O-K and Mn-L3 edges or fitting procedures with reference spectra of known oxidation state have been used as well 24 .…”

mentioning

confidence: 99%

“…In order to evaluate quantitatively the chemical shift observed in the Mn-L3,2 edge in the EELS spectra, a calibration curve has been built on the basis of the energy shifts in a series of 2p XAS spectra of several mixed valence manganites which have structure similar to the Ca1-xCexMnO3. The extracted chemical shifts, estimated as the barycenter of the Mn-L3 from XAS references of the manganite series Nd1-xCaxMnO3 7 , La1-xSrxMnO3 5 , CaMnOx 24 , with higher numbers of x values than our samples, are plotted as a function of doping concentration in Fig. 2(c).…”

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confidence: 99%

Depth Profiling Charge Accumulation from a Ferroelectric into a Doped Mott Insulator

et al. 2015

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The electric field control of functional properties is a crucial goal in oxide-based electronics.Non-volatile switching between different resistivity or magnetic states in an oxide channel can be achieved through charge accumulation or depletion from an adjacent ferroelectric. However, the way in which charge distributes near the interface between the ferroelectric and the oxide remains poorly known, which limits our understanding of such switching effects.Here we use a first-of-a-kind combination of scanning transmission electron microscopy with electron energy loss spectroscopy, near-total-reflection hard X-ray photoemission spectroscopy, and ab-initio theory to address this issue. We achieve a direct, quantitative, atomic-scale characterization of the polarization-induced charge density changes at the interface between the ferroelectric BiFeO3 and the doped Mott insulator Ca1-xCexMnO3, thus providing insight on how interface-engineering can enhance these switching effects. 3The ferroelectric control of functional properties in strongly correlated oxide nanostructures through electrostatic carrier density modulations has inspired intensive research efforts 1,2 .The field effect technique is particularly attractive for nanostructures consisting of complex oxides such as mixed-valence manganites, as these electron-correlated systems exhibit rich phase diagrams 3 .Hole-doped mixed-valence manganites with predominant Mn 3+ oxidation state have been extensively investigated [3][4][5][6][7][8] . In particular, recent works have been devoted on the interface between the half-metal La1-xSrxMnO3 (LSMO) manganite and ferroelectrics such as Pb(ZrxTi1- In these recent reports 13,14 , the resistivity change in the manganite channel induced by polarization switching in the ferroelectric BiFeO3 was limited to one order of magnitude while changes of several orders were reported for thin films of CaMnO3 tuned by different doping levels, strains or by electrolyte gating 12 . Typical electron injection of around 0.1 free electrons in the manganite channel were estimated by Hall measurements and associated with this resistivity change.A charge distribution measurement on a unit cell scale at the Ca manganite/ferroelectric interface is thus required to understand, control and possibly enhance the magnitude of the resistivity switching effects. In the present study, a first-of-a-kind combination of scanning transmission electron microscopy (STEM) coupled to electron energy loss spectroscopy (EELS) [15][16][17][18] , and grazing-incidence hard x-ray photoemission spectroscopy (HAXPES) in a near-total-reflection (NTR) condition have been used as site-sensitive valence probes to address the electronic and structural properties of BiFeO3 and Ca1-xCexMnO3 heterostructures (x=0, 2, 4 at.% nominal Ce concentrations) at the atomic scale. Our experimental results have also been compared to local density functional theory (DFT).We have used these two novel and complementary methods to evaluate electron densities in manganite oxides. ...

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Oxidation state and chemical shift investigation in transition metal oxides by EELS

Cited by 491 publications

References 89 publications

Materials News: Interfacial chemistry and atomic arrangement of ZrO2 − La2/3Sr1/3MnO3 pillar-matrix structures

Materials News: Interfacial chemistry and atomic arrangement of ZrO2 − La2/3Sr1/3MnO3 pillar-matrix structures

Vanadium Substitution in Li₂MnSiO₄/C as Positive Electrode for Li Ion Batteries

Depth Profiling Charge Accumulation from a Ferroelectric into a Doped Mott Insulator

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Oxidation state and chemical shift investigation in transition metal oxides by EELS

Cited by 491 publications

References 89 publications

Materials News: Interfacial chemistry and atomic arrangement of ZrO2 − La2/3Sr1/3MnO3 pillar-matrix structures

Materials News: Interfacial chemistry and atomic arrangement of ZrO2 − La2/3Sr1/3MnO3 pillar-matrix structures

Vanadium Substitution in Li2MnSiO4/C as Positive Electrode for Li Ion Batteries

Depth Profiling Charge Accumulation from a Ferroelectric into a Doped Mott Insulator

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Vanadium Substitution in Li₂MnSiO₄/C as Positive Electrode for Li Ion Batteries