ELNES of Iron Compounds

1990 ◽  
Vol 48 (2) ◽  
pp. 28-29
Author(s):  
Hiroki Kurata ◽  
Kazuhiro Nagai ◽  
Seiji Isoda ◽  
Takashi Kobayashi
Keyword(s):  
Energy Loss ◽  
Metal Ions ◽  
Energy Resolution ◽  
Transition Metal Oxides ◽  
Local Symmetry ◽  
Iron Compounds ◽  
Fine Structures ◽  
Electron Energy Loss ◽  
Fe Ions ◽  
Electron Energy Loss Spectra

Electron energy loss spectra of transition metal oxides, which show various fine structures in inner shell edges, have been extensively studied. These structures and their positions are related to the oxidation state of metal ions. In this sence an influence of anions coordinated with the metal ions is very interesting. In the present work, we have investigated the energy loss near-edge structures (ELNES) of some iron compounds, i.e. oxides, chlorides, fluorides and potassium cyanides. In these compounds, Fe ions (Fe2+ or Fe3+) are octahedrally surrounded by six ligand anions and this means that the local symmetry around each iron is almost isotropic.EELS spectra were obtained using a JEM-2000FX with a Gatan Model-666 PEELS. The energy resolution was about leV which was mainly due to the energy spread of LaB6 -filament. The threshole energies of each edges were measured using a voltage scan module which was calibrated by setting the Ni L3 peak in NiO to an energy value of 853 eV.

Parallel Detection of Electron Energy Loss Spectra in Direct Mode

1990 ◽  
Vol 48 (2) ◽  
pp. 82-83
Author(s):  
Eckhard Quandt ◽  
Stephan laBarré ◽  
Andreas Hartmann ◽  
Heinz Niedrig
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Large Angle ◽  
Maximum Energy ◽  
Semiconductor Detectors ◽  
Parallel Detection ◽  
Photodiode Arrays ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Due to the development of semiconductor detectors with high spatial resolution -- e.g. charge coupled devices (CCDs) or photodiode arrays (PDAs) -- the parallel detection of electron energy loss spectra (EELS) has become an important alternative to serial registration. Using parallel detection for recording of energy spectroscopic large angle convergent beam patterns (LACBPs) special selected scattering vectors and small detection apertures lead to very low intensities. Therefore the very sensitive direct irradiation of a cooled linear PDA instead of the common combination of scintillator, fibre optic, and semiconductor has been investigated. In order to obtain a sufficient energy resolution the spectra are optionally magnified by a quadrupole-lens system.The detector used is a Hamamatsu S2304-512Q linear PDA with 512 diodes and removed quartz-glas window. The sensor size is 13 μm ∗ 2.5 mm with an element spacing of 25 μm. Along with the dispersion of 3.5 μm/eV at 40 keV the maximum energy resolution is limited to about 7 eV, so that a magnification system should be attached for experiments requiring a better resolution.

EELS Investigations of Different Niobium Oxide Phases

2006 ◽  
Vol 12 (5) ◽  
pp. 416-423 ◽  
Author(s):  
D. Bach ◽  
H. Störmer ◽  
R. Schneider ◽  
D. Gerthsen ◽  
J. Verbeeck
Keyword(s):  
Energy Loss ◽  
Reference Materials ◽  
Niobium Oxide ◽  
Selected Area Electron Diffraction ◽  
Local Environments ◽  
Oxide Phases ◽  
Quantitative Manner ◽  
Fine Structures ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Electron energy loss spectra in conjunction with near-edge fine structures of purely stoichiometric niobium monoxide (NbO) and niobium pentoxide (Nb2O5) reference materials were recorded. The structures of the niobium oxide reference materials were checked by selected area electron diffraction to ensure a proper assignment of the fine structures. NbO and Nb2O5 show clearly different energy loss near-edge fine structures of the Nb-M4,5 and -M2,3 edges and of the O-K edge, reflecting the specific local environments of the ionized atoms. To distinguish the two oxides in a quantitative manner, the intensities under the Nb-M4,5 as well as Nb-M2,3 edges and the O-K edge were measured and their ratios calculated. k-factors were also derived from these measurements.

Transition metal oxides revisited: ELNES of metal L2,3 and oxygen K edges

1989 ◽  
Vol 47 ◽  
pp. 390-391
Author(s):  
Ondrej L. Krivanek ◽  
James H. Paterson ◽  
Helmut R. Poppa ◽  
P. Rez
Keyword(s):  
Transition Metal ◽  
Energy Loss ◽  
Metal Oxides ◽  
Chromium Oxide ◽  
Transition Metal Oxides ◽  
Thin Metal Film ◽  
Edge Structure ◽  
Thin Oxide Films ◽  
Fine Structures ◽  
Electron Energy Loss

When examined at 0.5 eV or better energy resolution by electron energy loss spectroscopy (EELS), many inner shell loss edges begin to show new fine structures. Recently, we have been able to acquire inner shell loss spectra routinely at about 0.4 eV resolution, using the Gatan PEELS™ on the VG HB501 STEM. We have therefore decided to reinvestigate the energy-loss near-edge structure (ELNES) of oxygen K and metal L2,3 edges in first row transition metal oxides.Figure 1 shows the metal L2,3 edges from vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, and copper oxide. Except for the chromium oxide sample, which was prepared by crushing and dispersing grains of crystalline Cr2O3, samples were made by vapor-depositing a thin metal film onto rock salt, heating it in air at about 400° C while still on the substrate, and subsequently floating it off. The resultant thin oxide films were from the same sample batches as those used for the EELS Atlas, where they were identified as VOx, MnO2, Fe2O3, CoO, NiO, and CuO.

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