scholarly journals Recent advances in small-angle electron diffraction and Lorentz microscopy

Microscopy ◽  
2020 ◽  
Author(s):  
Shigeo Mori ◽  
Hiroshi Nakajima ◽  
Atsuhiro Kotani ◽  
Ken Harada
Keyword(s):  
Electron Diffraction ◽  
Small Angle ◽  
Functional Materials ◽  
Angular Range ◽  
Multiferroic Materials ◽  
Lorentz Microscopy ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Magnetic Skyrmions ◽  
Conventional Transmission Electron Microscope

Abstract We describe small-angle electron diffraction (SmAED) and Lorentz microscopy using a conventional transmission electron microscope. In SmAED, electron diffraction patterns with a wide-angular range on the order of 1 × 10−2 rad to 1 × 10−7 rad can be obtained. It is demonstrated that magnetic information of nanoscale magnetic microstructures can be obtained by Fresnel imaging, Foucault imaging and SmAED. In particular, we report magnetic microstructures associated with magnetic stripes and magnetic skyrmions revealed by Lorentz microscopy with SmAED. SmAED can be applied to the analysis of microstructures in functional materials such as dielectric, ferromagnetic and multiferroic materials.

PM-17Magnetic Microstructures Observation of Functional Materials by Small Angle Electron Diffraction and Lorentz Microscopy

Microscopy ◽  
2017 ◽  
Vol 66 (suppl_1) ◽  
pp. i26-i26
Author(s):  
Hiroshi Nakajima ◽  
Atsuhiro Kotani ◽  
Ken Harada ◽  
Yui Ishii ◽  
Shigeo Mori
Keyword(s):  
Electron Diffraction ◽  
Small Angle ◽  
Functional Materials ◽  
Lorentz Microscopy

Magnetic Material Observation Assembly for Tem with a Eucentric Goniometer

1976 ◽  
Vol 34 ◽  
pp. 540-541
Author(s):  
K. Shi rota ◽  
A. Yonezawa ◽  
K. Shibatomi ◽  
T. Yanaka
Keyword(s):  
Magnetic Material ◽  
Electron Microscope ◽  
Magnetic Domain ◽  
Objective Lens ◽  
Magnetic Domains ◽  
Lorentz Microscopy ◽  
Transmission Electron ◽  
Correction Of Astigmatism ◽  
Single Orientation ◽  
Conventional Transmission Electron Microscope

As is well known, it is not so easy to operate a conventional transmission electron microscope for observation of magnetic materials. The reason is that the instrument requires re-alignment of the axis and re-correction of astigmatism after each specimen shift, as the lens field is greatly disturbed by the specimen. With a conventional electron microscope, furthermore, it is impossible to observe magnetic domains, because the specimen is magnetized to single orientation by the lens field. The above mentioned facts are due to the specimen usually being in the lens field. Thus, special techniques or systems are usually required for magnetic material observation (especially magnetic domain observation), for example, the technique to switch off the objective lens current and Lorentz microscopy. But these cannot give high image quality and wide magnification range, and furthermore Lorentz microscopy is very complicated.

An Interactive Minicomputer Program for the Indexing and Simulation of Electron Diffraction Patterns

1976 ◽  
Vol 34 ◽  
pp. 542-543
Author(s):  
R.P. Goehner ◽  
W.T. Hatfield ◽  
Prakash Rao
Keyword(s):  
Electron Diffraction ◽  
Real Time ◽  
Pattern Analysis ◽  
Flow Diagram ◽  
Hard Copy ◽  
Time Analysis ◽  
Real Time Analysis ◽  
Transmission Electron ◽  
One Step ◽  
Diffraction Patterns

Computer programs are now available in various laboratories for the indexing and simulation of transmission electron diffraction patterns. Although these programs address themselves to the solution of various aspects of the indexing and simulation process, the ultimate goal is to perform real time diffraction pattern analysis directly off of the imaging screen of the transmission electron microscope. The program to be described in this paper represents one step prior to real time analysis. It involves the combination of two programs, described in an earlier paper(l), into a single program for use on an interactive basis with a minicomputer. In our case, the minicomputer is an INTERDATA 70 equipped with a Tektronix 4010-1 graphical display terminal and hard copy unit.A simplified flow diagram of the combined program, written in Fortran IV, is shown in Figure 1. It consists of two programs INDEX and TEDP which index and simulate electron diffraction patterns respectively. The user has the option of choosing either the indexing or simulating aspects of the combined program.

A library of convergent-beam electron diffraction patterns

1986 ◽  
Vol 44 ◽  
pp. 688-691
Author(s):  
John F. Mansfield
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Transmission Electron ◽  
Yield Information ◽  
Analytical Electron ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Electron Energy Loss

One of the most important advancements of the transmission electron microscopy (TEM) in recent years has been the development of the analytical electron microscope (AEM). The microanalytical capabilities of AEMs are based on the three major techniques that have been refined in the last decade or so, namely, Convergent Beam Electron Diffraction (CBED), X-ray Energy Dispersive Spectroscopy (XEDS) and Electron Energy Loss Spectroscopy (EELS). Each of these techniques can yield information on the specimen under study that is not obtainable by any other means. However, it is when they are used in concert that they are most powerful. The application of CBED in materials science is not restricted to microanalysis. However, this is the area where it is most frequently employed. It is used specifically to the identification of the lattice-type, point and space group of phases present within a sample. The addition of chemical/elemental information from XEDS or EELS spectra to the diffraction data usually allows unique identification of a phase.

Structural studies of small amorphous volumes by electron diffraction

1990 ◽  
Vol 48 (4) ◽  
pp. 122-123
Author(s):  
Pierre Moine
Keyword(s):  
Electron Diffraction ◽  
Born Approximation ◽  
Structural Information ◽  
Fundamental Relation ◽  
X Rays ◽  
Structural Studies ◽  
Diffraction Experiment ◽  
Transmission Electron ◽  
Amorphous Structures ◽  
Diffraction Patterns

Qualitatively, amorphous structures can be easily revealed and differentiated from crystalline phases by their Transmission Electron Microscopy (TEM) images and their diffraction patterns (fig.1 and 2) but, for quantitative structural information, electron diffraction pattern intensity analyses are necessary. The parameters describing the structure of an amorphous specimen have been introduced in the context of scattering experiments which have been, so far, the most used techniques to obtain structural information in the form of statistical averages. When only small amorphous volumes (< 1/μm in size or thickness) are available, the much higher scattering of electrons (compared to neutrons or x rays) makes, despite its drawbacks, electron diffraction extremely valuable and often the only feasible technique.In a diffraction experiment, the intensity IN (Q) of a radiation, elastically scattered by N atoms of a sample, is measured and related to the atomic structure, using the fundamental relation (Born approximation) : IN(Q) = |FT[U(r)]|.

A Structural Model for a Quasi-Crystalline Material Derived from TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 48-49
Author(s):  
Jan-Olov Bovin ◽  
Osamu Terasaki ◽  
Jan-Olle Malm ◽  
Sven Lidin ◽  
Sten Andersson
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Structural Model ◽  
Image Intensifier ◽  
Crystalline Materials ◽  
Icosahedral Phases ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Diffraction Patterns ◽  
Quasi Crystals

High resolution transmission electron microscopy (HRTEM) is playing an important role in identifying the new icosahedral phases. The selected area diffraction patterns of quasi crystals, recorded with an aperture of the radius of many thousands of Ångströms, consist of dense arrays of well defined sharp spots with five fold dilatation symmetry which makes the interpretation of the diffraction process and the resulting images different from those invoked for usual crystals. The atomic structure of the quasi crystals is not established even if several models are proposed. The correct structure model must of course explain the electron diffraction patterns with 5-, 3- and 2-fold symmetry for the phases but it is also important that the HRTEM images of the alloys match the computer simulated images from the model. We have studied quasi crystals of the alloy Al65Cu20Fe15. The electron microscopes used to obtain high resolution electro micrographs and electron diffraction patterns (EDP) were a (S)TEM JEM-2000FX equipped with EDS and PEELS showing a structural resolution of 2.7 Å and a IVEM JEM-4000EX with a UHP40 high resolution pole piece operated at 400 kV and with a structural resolution of 1.6 Å. This microscope is used with a Gatan 622 TV system with an image intensifier, coupled to a YAG screen. It was found that the crystals of the quasi crystalline materials here investigated were more sensitive to beam damage using 400 kV as electron accelerating voltage than when using 200 kV. Low dose techniques were therefore applied to avoid damage of the structure.

scholarly journals Nano-Scale Rare Earth Distribution in Fly Ash Derived from the Combustion of the Fire Clay Coal, Kentucky

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 206 ◽  
Author(s):  
James Hower ◽  
Dali Qian ◽  
Nicolas Briot ◽  
Eduardo Santillan-Jimenez ◽  
Madison Hood ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Fly Ash ◽  
Electron Diffraction ◽  
Eastern Kentucky ◽  
Nano Scale ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Fire Clay

Fly ash from the combustion of eastern Kentucky Fire Clay coal in a southeastern United States pulverized-coal power plant was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). TEM combined with elemental analysis via energy dispersive X-ray spectroscopy (EDS) showed that rare earth elements (REE; specifically, La, Ce, Nd, Pr, and Sm) were distributed within glassy particles. In certain cases, the REE were accompanied by phosphorous, suggesting a monazite or similar mineral form. However, the electron diffraction patterns of apparent phosphate minerals were not definitive, and P-lean regions of the glass consisted of amorphous phases. Therefore, the distribution of the REE in the fly ash seemed to be in the form of TEM-visible nano-scale crystalline minerals, with additional distributions corresponding to overlapping ultra-fine minerals and even true atomic dispersion within the fly ash glass.

An electron diffraction and Monte Carlo simulation study of an incommensurate antiferroelectric state in the relaxor ferroelectric Pb2ScTaO6

2009 ◽  
Vol 43 (1) ◽  
pp. 140-150 ◽  
Author(s):  
K. Z. Baba-Kishi ◽  
M. Pasciak
Keyword(s):  
Monte Carlo ◽  
Electron Diffraction ◽  
Relaxor Ferroelectric ◽  
Advanced Degree ◽  
Monte Carlo Simulation Study ◽  
Transmission Electron ◽  
Incommensurate Modulation ◽  
Pb Ions ◽  
Specific Temperature ◽  
Diffraction Patterns

Incommensurate satellite reflections modulating along the 〈110〉* directions have been observed in the electron diffraction patterns of single crystals of the relaxor ferroelectric Pb2ScTaO6(PST) recordedviatransmission electron microscopy. The satellites occur characteristically within a specific temperature range and display differing or variable modulation vectors relative to their primary reflections. The satellites represent a weak frustrated antiferroelectric state in PST, termed the incommensurate antiferroelectric (IAFE) state. The observed IAFE state coexists with the ferroelectric and paraelectric states within a specific temperature regime and is dynamic in nature, meaning that the dispositions of the satellites can be altered by varying the temperature applied to the crystal,in-situin the transmission electron microscope. The observed satellites are associated with thin, needle-shaped, closely packed striated domains of about 5–15 nm in width. The satellites appear exclusively in crystals of PST with an advanced degree of 1:1 chemical long-range order, exceeding 90%. The satellites and their domains are interpreted as originating from a displacive, antiferroelectric coupling of the ions, driven in particular by the Pb ions. The Monte Carlo (MC) method was used exhaustively to evaluate the structural regimes that lead to the occurrence of the IAFE state. In the MC simulations, the displacements were correlated with the ferroelectric and antiferroelectric couplings, resulting in the IAFE domains and their associated satellites of differing dispositions or modulation vectors. The results of the MC simulations agree well with the electron diffraction observations, supporting the model of an antiferroelectric displacement with an incommensurate modulation of the Pb ions in the 〈110〉* directions.

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