Structural Properties and ELNES of Polycrystalline and Nanoporous Mg3N2

2020 ◽  
Vol 26 (1) ◽  
pp. 102-111
Author(s):  
Olivia Wenzel ◽  
Viktor Rein ◽  
Radian Popescu ◽  
Claus Feldmann ◽  
Dagmar Gerthsen
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Crystal Size ◽  
Bulk Material ◽  
Structural Features ◽  
Edge Structure ◽  
Transmission Electron ◽  
Potential Applications ◽  
Magnesium Nitride ◽  
Electron Energy Loss

AbstractNanoporous, high-purity magnesium nitride (Mg3N2) was synthesized with a liquid ammonia-based process, for potential applications in optoelectronics, gas separation and catalysis, since these applications require high material purity and crystallinity, which has seldom been demonstrated in the past. One way to evaluate the degree of crystalline near-range order and atomic environment is electron energy-loss spectroscopy (EELS) in a transmission electron microscope. However, there are hardly any data on Mg3N2, which makes identification of electron energy-loss near-edge structure (ELNES) features difficult. Therefore, we have studied nanoporous Mg3N2 with EELS in detail in comparison to EELS spectra of bulk Mg3N2, which was analyzed as a reference material. The N-K and Mg-K edges of both materials are similar. Despite having the same crystal structure, however, there are differences in fine-structural features, such as shifts and absences of peaks in the N-K and Mg-K edges of nanoporous Mg3N2. These differences in ELNES are attributed to coordination changes in nanoporous Mg3N2 caused by the significantly smaller crystallite size of 2–6 nm compared to the larger (25–125 nm) crystal size in a bulk material.

A Novel Technique for Determining Local Dielectric Function During Ferroelectric to Paraelectric Phase Transformation in Barium Titanate with a Transmission Eels

1995 ◽  
Vol 404 ◽  
Author(s):  
Kalpana S Katti ◽  
Maoxu Qian ◽  
Mehmet Sarikaya
Keyword(s):  
Phase Transformation ◽  
Barium Titanate ◽  
Energy Loss ◽  
Electron Energy ◽  
Dielectric Function ◽  
Optical Parameters ◽  
Edge Structure ◽  
Transmission Electron ◽  
Electron Energy Loss

AbstractIn this work a transmission electron microscopy (TEM) technique was used in obtaining local dielectric properties calculated from optical parameters for dynamic investigation of the effect of cubic to tetragonal phase transformation in barium titanate. In order to obtain in situ local dielectric during phase transformation, Kramers-Kronig relations were applied using the transmission electron energy loss (EELS) measurements. The optical excitations in the EELS spectra were consistent with the band structure results. The Re (1/ε) (real part of the dielectric function) obtained from the energy loss data indicated a change at the phase transformation. A broadening of the valence plasmon excitation suggested an order-disorder nature to the cubic to tetragonal transformation. In situ electron energy loss near edge structure (ELNES) studies from 500–700 eV energy range near the O-K edge exhibited a pre-edge feature that is associated with the Ti-L1, edge which further indicates an order-disorder nature to the phase transformation. The significance of the results is discussed.

Energy-filtering Transmission Electron Microscopy in materials and life science

1994 ◽  
Vol 52 ◽  
pp. 936-937
Author(s):  
L. Reimer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Analytical Electron Microscopy ◽  
Edge Structure ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Plasmon Loss ◽  
Electron Energy Loss

Energy-filtering transmission electron microscopy can be realized by an imaging filter lens in thecolumn of a TEM, a post-column electron energy-loss spectrometer or a dedicated STEM. This offers new possibilities in analytical electron microscopy by combining the operation modes of electron-spectroscopic imaging (ESI), electron-spectroscopic diffraction (ESD) and the record of an electron energy-loss spectrum (EELS).ESI can be used in the zero-loss mode to remove all inelastically scattered electrons. Thicker amorphous and crystalline specimens can be observed without chromatic aberration and with a transmissionof 10−3 up to 80(110) and 150(200) μg/cm2 at 80(120) keV, respectively. This results in a condiserable increase of scattering, phase and Bragg contrast, especially for low Z material because the ratio of inelastic-to-elastic cross section increases as 20/Z with decreasing atomic number. In future energy-filtered high-resolution crystal-lattice images will offer us a better comparison with dynamical simulations. Plasmon loss filtering can be applied for a better separation of phases (e.g. precipitates in a matrix), which differ in their plasmon loss by about 1 eV. Owing to intersections of the energy loss spectra, different parts of a specimen can change their contrast when tuning the selected energy window. Structures containing non carbon atoms will beconsiderably increased in a bright field like contrast relative to the carboneous matrix just below the carbon K edge (structure—sensitive imaging).

Simulation and Electron Energy-Loss Spectroscopy of Electron Beam Induced Point Defect Agglomerations in Silicon

2004 ◽  
Vol 810 ◽  
Author(s):  
Nathan G. Stoddard ◽  
Gerd Duscher ◽  
Wolfgang Windl ◽  
George A. Rozgonyi
Keyword(s):  
Energy Loss ◽  
Point Defect ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Edge Structure ◽  
Excited Atoms ◽  
Transmission Electron ◽  
Electronically Excited ◽  
Z Contrast ◽  
Electron Energy Loss

ABSTRACTNitrogen doped silicon samples were irradiated with 200 kV electrons in a transmission electron microscope (TEM). The resulting room temperature point defect creation, bonding and segregation were studied by in situ conventional and Z Contrast TEM imaging and electron energy loss spectroscopy (EELS). Energy loss spectra from areas attributed to be rich in vacancies or silicon self-interstitials are found to be significantly different from the bulk in the near-edge structure of their Si-L2,3 edges. The experimental results are compared with ab initio density of states calculations for electronically excited atoms near relaxed point defect structures and plans are outlined to extend this technique to individual point defect characterization.

First Applications of Electron Energy-Loss Spectroscopy with High Energy Resolution

2002 ◽  
Vol 738 ◽  
Author(s):  
Gerald Kothleitner ◽  
Christoph Mitterbauer ◽  
Werner Grogger ◽  
Henny Zandbergen ◽  
Peter Tiemeijer ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Chemical Bonding ◽  
High Energy ◽  
Structural Features ◽  
High Energy Resolution ◽  
Transmission Electron ◽  
New Instrument ◽  
Electron Energy Loss

ABSTRACTA new transmission electron microscope equipped with a monochromator and a high resolution energy-filter was used for the first time to fully exploit the chemical bonding information contained in the near edge fine structures (ELNES) of electron energy-loss spectra. The instrument is capable of acquiring spectra with an energy resolution in the range of 0.1 eV, thus opening up the way for improved ELNES information. ELNES spectra of TiO2 and CoO have been recorded and are compared with data obtained with a conventional microscope and with x-ray absorption spectroscopy. In case of the L2,3 edges of the transition metals the new instrument revealed previously unobservable fine structure details, but for the O K edges the improved energy resolution does not result in more detailed structural features than observable in common microscopes. Furthermore, the potential of the new microscope to obtain chemical bonding information at the nanometer scale is discussed.

Electron energy-loss near-edge structure in silicate minerals

1992 ◽  
Vol 50 (2) ◽  
pp. 1258-1259
Author(s):  
D W McComb ◽  
R S Payne ◽  
P L Hansen ◽  
R Brydson
Keyword(s):  
Solid State ◽  
Energy Loss ◽  
Electron Energy ◽  
State Energy ◽  
Local Environment ◽  
Edge Structure ◽  
Silicate Minerals ◽  
Two Samples ◽  
Electron Energy Loss ◽  
Careful Processing

Electron energy-loss near-edge structure (ELNES) is an effective probe of the local geometrical and electronic environment around particular atomic species in the solid state. Energy-loss spectra from several silicate minerals were mostly acquired using a VG HB501 STEM fitted with a parallel detector. Typically a collection angle of ≈8mrad was used, and an energy resolution of ≈0.5eV was achieved.Other authors have indicated that the ELNES of the Si L2,3-edge in α-quartz is dominated by the local environment of the silicon atom i.e. the SiO4 tetrahedron. On this basis, and from results on other minerals, the concept of a coordination fingerprint for certain atoms in minerals has been proposed. The concept is useful in some cases, illustrated here using results from a study of the Al2SiO5 polymorphs (Fig.l). The Al L2,3-edge of kyanite, which contains only 6-coordinate Al, is easily distinguished from andalusite (5- & 6-coordinate Al) and sillimanite (4- & 6-coordinate Al). At the Al K-edge even the latter two samples exhibit differences; with careful processing, the fingerprint for 4-, 5- and 6-coordinate aluminium may be obtained.

Investigation of Switching Mechanism in HfO2-Based Oxide Resistive Memories by In-Situ Transmission Electron Microscopy and Electron Energy Loss Spectroscopy

2017 ◽  
Author(s):  
T. Dewolf ◽  
D. Cooper ◽  
N. Bernier ◽  
V. Delaye ◽  
A. Grenier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Hafnium Dioxide ◽  
Switching Mechanism ◽  
Transmission Electron ◽  
Electron Energy Loss

Abstract Forming and breaking a nanometer-sized conductive area are commonly accepted as the physical phenomenon involved in the switching mechanism of oxide resistive random access memories (OxRRAM). This study investigates a state-of-the-art OxRRAM device by in-situ transmission electron microscopy (TEM). Combining high spatial resolution obtained with a very small probe scanned over the area of interest of the sample and chemical analyses with electron energy loss spectroscopy, the local chemical state of the device can be compared before and after applying an electrical bias. This in-situ approach allows simultaneous TEM observation and memory cell operation. After the in-situ forming, a filamentary migration of titanium within the dielectric hafnium dioxide layer has been evidenced. This migration may be at the origin of the conductive path responsible for the low and high resistive states of the memory.

Combined ab-initio and N-K, Ti-L2,3, V-L2,3 electron energy-loss near edge structure studies for TiN and VN films

2007 ◽  
Vol 98 (11) ◽  
pp. 1060-1065 ◽  
Author(s):  
Boriana Rashkova ◽  
Petr Lazar ◽  
Josef Redinger ◽  
Raimund Podloucky ◽  
Gerald Kothleitner ◽  
...  
Keyword(s):  
Energy Loss ◽  
Ab Initio ◽  
Electron Energy ◽  
Edge Structure ◽  
Electron Energy Loss
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