Chemistry and Bonding at {222}Mgo/Cu Heterophase Interfaces

1997 ◽  
Vol 3 (S2) ◽  
pp. 647-648
Author(s):  
D. A. Müller ◽  
D. A. Shashkov ◽  
R. Benedek ◽  
L. H. Yang ◽  
D. N. Seidman ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Fine Structure ◽  
Energy Loss ◽  
High Spatial Resolution ◽  
Experimental Studies ◽  
Electronic States ◽  
Atomic Scale ◽  
Interfacial Chemistry ◽  
Local Electronic Structure ◽  
Electron Energy Loss

Adhesion at ceramic/metal (C/M) interfaces often controls the macroscopic behavior of materials containing metallic and ceramic phases, and experimental studies of bonding at C/M interfaces have recently been reported. Electron energy loss spectroscopy (EELS) offers unique opportunities to examine bonding at interfaces on an atomic scale. The EELS near edge fine structure is sensitive to local atomic arrangements and thus can be used as a coordination fingerprint. Much more can be done, however, by analyzing the connection between the EELS fine structure, the underlying local electronic structure and the cohesive energy of an interface to gain a deeper understanding of the nature of the adhesion at the interface.In this work, we apply high spatial-resolution EELS instrument to study {222} MgO/Cu interfaces produced by internal oxidation. We determine interfacial chemistry of this interface with subnanometer resolution (Fig. 1) and use EELS to directly measure the electronic states pertaining to the interface

Local Electronic Structure Of Defects In Gan From Spatially Resolved Electron Energy-Loss Spectroscopy

1997 ◽  
Vol 482 ◽  
Author(s):  
M. K. H. Natusch ◽  
G. A. Botton ◽  
R. F. Broom ◽  
P. D. Brown ◽  
D. M. Tricker ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Crystal Defects ◽  
Vacuum Field ◽  
Spatially Resolved ◽  
Local Electronic Structure ◽  
Electron Energy Loss

AbstractThe optical properties and their modification by crystal defects of wurtzite GaN are investigated using spatially resolved electron energy-loss spectroscopy (EELS) in a dedicated ultra-high vacuum field emission gun scanning transmission electron microscope. The calculated density of states of the bulk crystal reproduces well the features of the measured spectra. The profound effect of a prismatic stacking fault on the local electronic structure is shown by the spatial variation of the optical properties derived from low-loss spectra. It is found that a defect state at the fault appears to bind 1.5 electrons per atom.

scholarly journals Atomic scale crystal field mapping of polar vortices in oxide superlattices

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sandhya Susarla ◽  
Pablo García-Fernández ◽  
Colin Ophus ◽  
Sujit Das ◽  
Pablo Aguado-Puente ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Crystal Field ◽  
First Principles ◽  
Atomic Scale ◽  
First Principles Calculations ◽  
Edge Structure ◽  
Electron Energy Loss ◽  
Complex Polarization ◽  
Good Agreement

AbstractPolar vortices in oxide superlattices exhibit complex polarization topologies. Using a combination of electron energy loss near-edge structure analysis, crystal field multiplet theory, and first-principles calculations, we probe the electronic structure within such polar vortices in [(PbTiO3)16/(SrTiO3)16] superlattices at the atomic scale. The peaks in Ti $$L$$ L -edge spectra shift systematically depending on the position of the Ti4+ cations within the vortices i.e., the direction and magnitude of the local dipole. First-principles computation of the local projected density of states on the Ti $$3d$$ 3 d orbitals, together with the simulated crystal field multiplet spectra derived from first principles are in good agreement with the experiments.

Electron Energy Loss Fine Structure of Carbides and Nitrides

1985 ◽  
Vol 62 ◽  
Author(s):  
Mark M. Disko
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
High Strength ◽  
Analytical Technique ◽  
Wide Range ◽  
Wear Coatings ◽  
Electron Energy Loss

ABSTRACTTransition metal carbides and nitrides are important in a wide range of materials problems which include precipitates in high strength alloys and ceramic wear coatings. Electron energy loss spectroscopy (EELS) is a high spatial resolution (probe sizes < 100nm) analytical technique which is sensitive to variations in carbon or nitrogen stoichiometry. This sensitivity to light elements depends on the ability to relate the measured EELS spectrum to a material's electronic structure. The unique capabilities of EELS for the characterization of carbonitrides with high spatial resolution are discussed along with some of the experimental and analytical methods used to relate measured spectra to electronic structure. Data are presented for several members of the systems Ti-N-C and Cr-Fe-C.

Investigations of Bonding in Skutterudites by Electron Energy-Loss Spectroscopy

2007 ◽  
Vol 1044 ◽  
Author(s):  
Oystein Prytz ◽  
Ragnhild Saterli ◽  
Randi Holmestad ◽  
Johan Tafto
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Fermi Level ◽  
Ab Initio ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Filled Skutterudite ◽  
Local Electronic Structure ◽  
Electron Energy Loss

AbstractThe local electronic structure of phosphorus in the binary skutterudites CoP3 and NiP3, and in the filled skutterudite LaFe4P12 are studied using a combination of electron energy-loss spectroscopy and ab initio calculations. Relative to CoP3 we observe a filling of phosphorus s and d states in NiP3, while for LaFe4P12 increased EELS intensity indicates more empty s and d states close to the Fermi-level.

Improved Measurement and Analysis of Series of Valence Electron Energy Loss Spectra and The Local Electronic Structure

1997 ◽  
Vol 3 (S2) ◽  
pp. 943-944
Author(s):  
H. Müllejans ◽  
R. H. French ◽  
G. Duscher ◽  
M. Rühle
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Valence Electron ◽  
Primary Electron ◽  
Full Data ◽  
Data Set ◽  
Automatic Data ◽  
Local Electronic Structure ◽  
Electron Energy Loss

The local electronic structure of ceramic materials can be determined from valence electron energy loss (Veel) spectra via the dielectric function. The quality of the data is comparable to vacuum ultraviolet spectroscopy with the added benefit of high spatial resolution. We have built and implemented a system for spectrum imaging which not only allows automatic data acquisition but also analysis of the full data set. The system consists of a Gatan PEELS and a Gatan Digiscan fitted to a VG HB501 UX STEM and home-built hardware additions. The hardware extensions allow to acquire 1, 2, 3, 4 or 8 spectra for each pixel and in the case of 2 spectra/pixel to vary the exposure time of the specimen to the primary electron beam by controlling the beam blanker (Fig. 1). The first spectrum (2 to 20 ms) contains an unsaturated zero loss peak and the second spectrum (0.05 to 100 s) at the same position the plasmon peak near to but below saturation (Fig. 2).

Chemical analyses and studies of electronic structure of solids by electron energy loss spectroscopy with an electron microscope

1986 ◽  
Vol 318 (1541) ◽  
pp. 259-281 ◽  
Keyword(s):  
Electronic Structure ◽  
Fine Structure ◽  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Alkali Metals ◽  
Transition Elements ◽  
White Line ◽  
Edge Structure ◽  
Electron Energy Loss

Both the thickness and the composition of a specimen can be deduced from plasmon spectroscopy, which is readily recorded with an electron microscope to which has been attached an electron spectrometer of resolution 1—3 eV. This is illustrated in the study of alkali metals and sp metals such as magnesium and aluminium , which are produced by decomposing ternary or binary hydrides (for example, NaAlH 4 or MgH 2 ). But other m aterials, including silicon, are also am enable to studies of this kind. The elemental composition, electronic structure and inter-atomic distances of a sample can be derived from the core-electron (K, L, M edge) loss peaks and their fine structure. And from the near-edge energy loss structure, and in particular from the ‘white line’ intensity ratios (for example, L 2 /L 3 ), the number of d-electrons and hence the oxidation state of transition elements in com pounds of first-row transition metal series may be determined. In the region beyond the near-edge structure, extended electron energy loss fine structure (e.x.e.l.f.s.) is observed and this may be used to obtain information about the local co-ordination of different atoms in the sample. Finally, by monitoring the Doppler broadening of the scattered electrons liberated from the sample as a consequence of the ‘electron' equivalent of the Compton-process, we can probe the electronic properties of the solid in m omentum space. This reveals the nature of the bonding in simple solids; and, in particular, reveals whether an amorphous sample of carbon is more nearly graphitic or adamantine.

The Local Electronic structure at Grain Boundaries and Hetero- Interfaces in ZnO Thin Films Grown by Laser Deposition.

2002 ◽  
Vol 727 ◽  
Author(s):  
Alexander Kvit ◽  
Gerd Duscher ◽  
Chunming Jin ◽  
Jagdish Narayan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electronic Structure ◽  
High Resolution ◽  
Energy Loss ◽  
Grain Boundaries ◽  
Laser Deposition ◽  
Transmission Electron ◽  
Local Electronic Structure ◽  
Electron Energy Loss

AbstractThe structure and chemistry of interfaces and grain boundaries are known to influence the optical and electrical properties of wide-band gap semiconductors structures. ZnO/AlN/Si(100) heterostructures grown by laser deposition were studied by conventional and high-resolution transmission electron microscopy (HRTEM). The local electronic structure of ZnO grain boundaries was investigated by high resolution Z-contrast imaging using scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy in a scanning mode. Zcontrast imaging and EELS were performed simultaneously enabling direct correlations between interface chemistry and local structure to be made. ZnO grain boundaries are composed of a periodic array of a basic structural unit. On the basis of the electron energy-loss near-edge structure (ELNES) of zinc and oxygen edges associated with the ZnO- grain boundaries, the corresponding electronic spectrum was discussed.

Atomic resolution characterisation of interface structures by Electron Energy Loss Spectroscopy

1993 ◽  
Vol 51 ◽  
pp. 576-577
Author(s):  
N. D. Browning ◽  
M. M. McGibbon ◽  
M. F. Chisholm ◽  
S. J. Pennycook
Keyword(s):  
High Resolution ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Imaging Technique ◽  
Atomic Scale ◽  
Atomic Resolution ◽  
Reference Image ◽  
The Impact ◽  
Electron Energy Loss

The recent development of the Z-contrast imaging technique for the VG HB501 UX dedicated STEM, has added a high-resolution imaging facility to a microscope used mainly for microanalysis. This imaging technique not only provides a high-resolution reference image, but as it can be performed simultaneously with electron energy loss spectroscopy (EELS), can be used to position the electron probe at the atomic scale. The spatial resolution of both the image and the energy loss spectrum can be identical, and in principle limited only by the 2.2 Å probe size of the microscope. There now exists, therefore, the possibility to perform chemical analysis of materials on the scale of single atomic columns or planes.In order to achieve atomic resolution energy loss spectroscopy, the range over which a fast electron can cause a particular excitation event, must be less than the interatomic spacing. This range is described classically by the impact parameter, b, which ranges from ~10 Å for the low loss region of the spectrum to <1Å for the core losses.

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