EELS of Niobium and Stoichiometric Niobium-Oxide Phases—Part I: Plasmon and Near-Edges Fine Structure

2009 ◽  
Vol 15 (6) ◽  
pp. 505-523 ◽  
Author(s):  
David Bach ◽  
Reinhard Schneider ◽  
Dagmar Gerthsen ◽  
Jo Verbeeck ◽  
Wilfried Sigle
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Chemical Shifts ◽  
Primary Electron ◽  
White Line ◽  
Wide Range ◽  
Experimental Parameters ◽  
Oxide Phases ◽  
Energy Convergence ◽  
Electron Energy Loss

AbstractA comprehensive electron energy-loss spectroscopy study of niobium (Nb) and stable Nb-oxide phases (NbO, NbO2, Nb2O5) was carried out. In this work (Part I), the plasmons and energy-loss near-edge structures (ELNES) of all relevant Nb edges (Nb-N2,3, Nb-M4,5, Nb-M2,3, Nb-M1, and Nb-L2,3) up to energy losses of about 2600 eV and the O-K edge are analyzed with respect to achieving characteristic fingerprints of Nb in different formal oxidation states (0 for metallic Nb, +2 for NbO, +4 for NbO2, and +5 for Nb2O5). Chemical shifts of the Nb-N2,3, Nb-M4,5, Nb-M2,3, and Nb-L2,3 edges are extracted from the spectra that amount to about 4 eV as the oxidation state increases from 0 for Nb to +5 for Nb2O5. Four different microscopes, including a 200 keV ZEISS Libra with monochromator, were used. The corresponding wide range of experimental parameters with respect to the primary electron energy, convergence, and collection semi-angles as well as energy resolution allows an assessment of the influence of the experimental setup on the ELNES of the different edges. Finally, the intensity of the Nb-L2,3 white-line edges is correlated with niobium 4d-state occupancy in the different reference materials.

The Measured Change in d-Electron of Ni in Ni-7.2at%Ti Alloy Studied by Electron Energy Loss Spectroscopy

2014 ◽  
Vol 887-888 ◽  
pp. 370-373
Author(s):  
Wei Guo Yang
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Line Intensity ◽  
Ti Alloy ◽  
White Line ◽  
Measured Change ◽  
Electron Energy Loss

A Ni-7.2at%Ti alloy was prepared and thed-electron occupancy of Ni was measured from electron energy loss spectroscopy (EELS) of nickel. The results showed that the white-line intensity of Ni EELS and thed-electron occupancy of Ni in Ni-7.2at%Ti alloy did not change significantly relative to pure Ni.

Can the Number of D Electrons in Transition Metals be Measured from White Lines?

1997 ◽  
Vol 3 (S2) ◽  
pp. 957-958 ◽  
Author(s):  
P. Rez
Keyword(s):  
Transition Metals ◽  
Energy Loss ◽  
Electron Energy ◽  
Transition Elements ◽  
White Line ◽  
Line Intensities ◽  
Continuum Region ◽  
The Matrix ◽  
Image Position ◽  
Electron Energy Loss

Sharp peaks at threshold are a prominent feature of the L23 electron energy loss edges of both first and second row transition elements. Their intensity decreases monotonically as the atomic number increases across the period. It would therefore seem likely that the number of d electrons at a transition metal atom site and any variation with alloying could be measured from the L23 electron energy loss spectrum. Pearson measured the white line intensities for a series of both 3d and 4d transition metals. He normalised the white line intensity to the intensity in a continuum region 50eV wide starting 50eV above threshold. When this normalised intensity was plotted against the number of d electrons assumed for each elements he obtained a monotonie but non linear variation. The energy loss spectrum is given bywhich is a product of p<,the density of d states, and the matrix elements for transitions between 2p and d states.

Charge transfer in binary alloys: A future for electron energy loss spectroscopy in materials science

1988 ◽  
Vol 46 ◽  
pp. 2-5
Author(s):  
C. C. Ahn ◽  
D. H. Pearson ◽  
B. T. Fultz
Keyword(s):  
Charge Transfer ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Bound States ◽  
Binary Alloys ◽  
Threshold Energy ◽  
Enthalpies Of Formation ◽  
White Line ◽  
Electron Energy Loss

The redistribution of atomic charge which takes place from an atom of one type to that of another in a binary alloy system is fundamental to the formulation of models of enthalpies of formation of these systems. Of special interest are charge transfers where one of the alloy constituents is from the first row transition series. The extent to which the 3d band is filled, ultimately plays an important role in the propensity with which alloys will form intermetallic phases. An understanding of electron charge transfer is important not only in crystalline systems but can also serve as the basis for the determination of the extent of chemical short range order (CSRO) in amorphous binary alloys.Electron energy loss spectroscopy (EELS) in the electron microscope can probe unoccupied bound states and unlike other spectroscopies which probe core levels, is not surface sensitive. The features of the energy loss spectra of the 3d metals which make charge transfer studies possible are the L23 transitions. These spectra are characterized by two “white lines” at the threshold energy which result from ionizations from the 2p3/2 and 2p1/2 spin orbit subshells to a narrow bound 3d state. Beneath and beyond the white line transitions are transitions to the continuum states.

Fast Mapping of the Cobalt-Valence State in Ba0.5Sr0.5Co0.8Fe0.2O3-dby Electron Energy Loss Spectroscopy

2013 ◽  
Vol 19 (6) ◽  
pp. 1595-1605 ◽  
Author(s):  
Philipp Müller ◽  
Matthias Meffert ◽  
Heike Störmer ◽  
Dagmar Gerthsen
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Valence State ◽  
Hexagonal Phase ◽  
Fast Method ◽  
White Line ◽  
Valence States ◽  
Electron Energy Loss

AbstractA fast method for determination of the Co-valence state by electron energy loss spectroscopy in a transmission electron microscope is presented. We suggest the distance between the Co-L3and Co-L2white-lines as a reliable property for the determination of Co-valence states between 2+ and 3+. The determination of the Co-L2,3white-line distance can be automated and is therefore well suited for the evaluation of large data sets that are collected for line scans and mappings. Data with a low signal-to-noise due to short acquisition times can be processed by applying principal component analysis. The new technique was applied to study the Co-valence state of Ba0.5Sr0.5Co0.8Fe0.2O3-d(BSCF), which is hampered by the superposition of the Ba-M4,5white-lines on the Co-L2,3white-lines. The Co-valence state of the cubic BSCF phase was determined to be 2.2+ (±0.2) after annealing for 100 h at 650°C, compared to an increased valence state of 2.8+ (±0.2) for the hexagonal phase. These results support models that correlate the instability of the cubic BSCF phase with an increased Co-valence state at temperatures below 840°C.

Highly Automated Electron Energy-Loss Spectroscopy Elemental Quantification

2014 ◽  
Vol 20 (3) ◽  
pp. 798-806 ◽  
Author(s):  
Raman D. Narayan ◽  
J. K. Weiss ◽  
Peter Rez
Keyword(s):  
User Interface ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Single Scattering ◽  
Ease Of Use ◽  
Low Loss ◽  
Wide Range ◽  
Fitting Algorithm ◽  
Electron Energy Loss

AbstractA model-based fitting algorithm for electron energy-loss spectroscopy spectra is introduced, along with an intuitive user-interface. As with Verbeeck & Van Aert, the measured spectrum, rather than the single scattering distribution, is fit over a wide range. An approximation is developed that allows for accurate modeling while maintaining linearity in the parameters that represent elemental composition. Also, a method is given for generating a model for the low-loss background that incorporates plural scattering. Operation of the user-interface is described to demonstrate the ease of use that allows even nonexpert users to quickly obtain elemental analysis results.

QUANTITATIVE ANALYSIS OF NONCONTINUOUS THIN FILMS BY EELS

1999 ◽  
Vol 06 (05) ◽  
pp. 801-804 ◽  
Author(s):  
V. MATOLÍN ◽  
I. STARÁ
Keyword(s):  
Thin Films ◽  
Quantitative Analysis ◽  
Differential Cross Section ◽  
Energy Loss ◽  
Electron Energy ◽  
Cross Section ◽  
Sapphire Substrate ◽  
Primary Electron ◽  
Electron Energy Loss ◽  
Reference Samples

Reflection electron energy loss spectroscopy (EELS) operated at low primary electron energy Ep (~ 500 eV) can be used as a coverage-sensitive probe in the case of supported noncontinuous layers. Quantitative analysis by EELS is substantially complicated by the fact that EEL intensity depends on two material factors: K(E), differential cross section for energy loss of E, and electron backscattering factor η(Ep). Both factors were determined experimentally using deposit and substrate reference samples. The contribution of pure substrate and pure deposit EEL curves to composed EEL spectra of the investigated deposit/substrate system has been found by fitting it with combination of reference K(E)λ curves (λ stands for IMFP). The fit results corrected using η(Ep) factors permitted one to evaluate the deposit coverage. The method was tested using the reference Au fractional deposit on the sapphire substrate.

The Influence of Ti on d-Electron Occupancy of Fe in Fe-1.7%Ti Alloy

2013 ◽  
Vol 395-396 ◽  
pp. 259-261
Author(s):  
Wei Guo Yang ◽  
De Hui Li ◽  
Hong Jin Cai ◽  
Xin Cai ◽  
Huan Chen ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Line Intensity ◽  
Pure Iron ◽  
Ti Alloy ◽  
White Line ◽  
Electron Energy Loss

An Fe-1.7wt% Ti alloy was prepared and the electron energy loss spectroscopy (EELS) of iron was collected. Thed-electron occupancy of Fe is measured from the white-line intensity of EELS. It was found that relative to pure iron thed-electron occupancy of Fe in Fe-1.7wt% Ti alloy increased.

The Change of L Edge of Electron Energy Loss Spectroscopy of Ni in Ni-Based Solid-Solution Alloys

2012 ◽  
Vol 548 ◽  
pp. 221-224
Author(s):  
W.G. Yang ◽  
Y. Cheng
Keyword(s):  
Solid Solution ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Line Intensity ◽  
White Line ◽  
Electron Energy Loss

The electron energy loss spectroscopy (EELS) of Ni in a series of Ni-based solid-solution alloys and pure Ni has been collected. It is found that the distance between L2 and L3 peaks of Ni EELS is enlarged in all alloys relative to pure Ni. The d-electron occupancy of Ni in all alloys is measured from the white-line intensity of EELS and the results vary very small.

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