Energy Filtered Imaging and Convergent Beam Electron Diffraction (CBED) in the Transmission Electron Microscope (TEM)

Over the last ten years TEMs have been developed that are capable of HREM, EDX, PEELS and diffraction using a single objective pole piece. More recently these TEMs have been equipped with the capability of energy filtering the electron beam after it has passed through the sample so that energy filtered images and electron diffraction patterns can be obtained. In this work the use of a Topcon 002B TEM equipped with a GATAN PEELS imaging filter (GIF) to generate zero-loss energy filtered zone axis CBED patterns and elemental images from inelastically scattered electrons will be described. An analysis of this energy filtered data indicates that elemental imaging using the GIF is an informative, but semiquantitative technique, whereas zero-loss energy filtered zone axis CBED patterns can be accurately quantified so that the two lowest-angle x-ray form factors of cubic elements can be measured with errors of the order of 0.1% or less.

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A library of convergent-beam electron diffraction patterns

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144826 ◽

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.

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Convergent-beam electron diffraction at high spatial resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130390 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1152-1153 ◽

Cited By ~ 1

Author(s):

J W Steeds

Keyword(s):

Electron Diffraction ◽

High Temperature Superconductors ◽

Bloch Wave ◽

Convergent Beam Electron Diffraction ◽

Beam Electron ◽

Energy Filtering ◽

Small Probe ◽

Transmission Electron ◽

Electron Microscopes ◽

Convergent Beam

That the techniques of convergent beam electron diffraction (CBED) are now widely practised is evident, both from the way in which they feature in the sale of new transmission electron microscopes (TEMs) and from the frequency with which the results appear in the literature: new phases of high temperature superconductors is a case in point. The arrival of a new generation of TEMs operating with coherent sources at 200-300kV opens up a number of new possibilities.First, there is the possibility of quantitative work of very high accuracy. The small probe will essentially eliminate thickness or orientation averaging and this, together with efficient energy filtering by a doubly-dispersive electron energy loss spectrometer, will yield results of unsurpassed quality. The Bloch wave formulation of electron diffraction has proved itself an effective and efficient method of interpreting the data. The treatment of absorption in these calculations has recently been improved with the result that <100> HOLZ polarity determinations can now be performed on III-V and II-VI semiconductors.

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Measurement of Debye-Waller factors of silicon as a function of temperature using energy-filtered CBED rocking-curve technique

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172711 ◽

1994 ◽

Vol 52 ◽

pp. 996-997

Author(s):

S. Swaminathan ◽

S. Altynov ◽

I. P. Jones ◽

N. J. Zaluzec ◽

D. M. Maher ◽

...

Keyword(s):

Electron Diffraction ◽

Liquid Nitrogen Temperature ◽

Convergent Beam Electron Diffraction ◽

Higher Order ◽

X Ray Diffraction ◽

Beam Electron ◽

X Ray ◽

Crystal Potential ◽

Transmission Electron ◽

Convergent Beam

The advantages of quantitative Convergent Beam Electron Diffraction (CBED) method for x-ray structure factor determination have been reviewed by Spence. The CBED method requires accurate values of Debye-Waller (D-W) factors for the estimation of the coefficients of crystal potential of the higher order beams, Vg, the calculation of the absorption potential, V′g using the Einstein model for phonons, and finally the conversion of the fitted values of the coefficients of crystal potential, V″, to x-ray structure factors. Debye-Waller factors are conventionally determined by neutron or x-ray diffraction methods. Because of the difficulties in conducting high temperature neutron and x-ray diffraction experiments, D-W factors are rarely measured at temperatures above room temperature. Debye-Waller factors at high temperatures can be determined by Convergent Beam Electron diffraction (CBED) method using Transmission Electron Microscopy (TEM) employed with a hot stage attachment. Recently Holmestad et al. have attempted to measure the D-W factors by matching the energy-filtered Higher Order Laue Zone (HOLZ) line intensities near liquid nitrogen temperature.

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New Applications of Electron Diffraction in the Pharmaceutical Industry: Polymorph Determination by Using a Combination of Electron Diffraction and Synchrotron X-ray Powder Diffraction Techniques

Microscopy and Microanalysis ◽

10.1017/s1431927601020050 ◽

2002 ◽

Vol 8 (2) ◽

pp. 134-138 ◽

Cited By ~ 6

Author(s):

Z.G. Li ◽

R.L. Harlow ◽

C.M. Foris ◽

H. Li ◽

P. Ma ◽

...

Keyword(s):

Pharmaceutical Industry ◽

Electron Diffraction ◽

Powder Diffraction ◽

Unit Cell ◽

X Ray ◽

Cell Parameters ◽

Synchrotron Powder Diffraction ◽

Transmission Electron ◽

Diffraction Patterns ◽

New Applications

Electron diffraction has been recently used in the pharmaceutical industry to study the polymorphism in crystalline drug substances. While conventional X-ray diffraction patterns could not be used to determine the cell parameters of two forms of the microcrystalline GP IIb/IIIa receptor antagonist roxifiban, a combination of electron single-crystal and synchrotron powder diffraction techniques were able to clearly distinguish the two polymorphs. The unit-cell parameters of the two polymorphs were ultimately determined using new software routines designed to take advantage of each technique's unique capabilities. The combined use of transmission electron microscopy (TEM) and synchrotron patterns appears to be a good general approach for characterizing complex (low-symmetry, large-unit-cell, micron-sized) polymorphic pharmaceutical compounds.

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Enhanced Solubility of Cu in Ag Nanoparticles Synthesized by Inert Gas Condensation

MRS Proceedings ◽

10.1557/proc-854-u5.5 ◽

2004 ◽

Vol 854 ◽

Author(s):

Abdullah Ceylan ◽

C. Ni ◽

S. Ismat Shah

Keyword(s):

Electron Diffraction ◽

Systematic Change ◽

X Ray Diffraction ◽

X Ray ◽

Cu Alloy ◽

Transmission Electron ◽

Vegard’S Law ◽

Enhanced Solubility ◽

Diffraction Patterns ◽

Metal Flux

ABSTRACTAg-Cu alloy nanoparticles were prepared by rapid condensation of metal flux obtained by the simultaneous evaporation of high purity Cu and Ag wires on a tungsten boat in the presence of circulating He gas. Structural properties of the samples prepared at different conditions were investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area diffraction (SAD) patterns. X-ray diffraction patterns showed that particles were phase separated. The particle size obtained either from Scherer's formula or the TEM images show no systematic change on the size of either Cu or Ag particles in the evaporation temperature range between 800 and 1400 °C. By using lattice constant values and Vegard's law, the composition of the particles was calculated to be 6.6 vol% Cu in Ag. Electron diffraction images revealed that particles were softly agglomerated; these electron diffraction results were also consistent with XRD results regarding phase separation. Individual diffraction rings of the Cu and Ag were observed in the SAD patterns.

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New Features in Crystal Orientation and Phase Mapping for Transmission Electron Microscopy

Symmetry ◽

10.3390/sym13091675 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1675

Author(s):

Edgar F. Rauch ◽

Patrick Harrison ◽

Muriel Véron

Keyword(s):

Electron Diffraction ◽

Angular Resolution ◽

X Ray ◽

Amorphous Phases ◽

Transmission Electron ◽

Tremendous Amount ◽

Processing Algorithms ◽

Electron Microscopes ◽

Diffraction Patterns ◽

Scanning Electron Microscopes

ACOM/TEM is an automated electron diffraction pattern indexing tool that enables the structure, phase and crystallographic orientation of materials to be routinely determined. The software package, which is part of ACOM/TEM, has substantially evolved over the last fifteen years and has pioneered numerous additional functions with the constant objective of improving its capabilities to make the tremendous amount of information contained in the diffraction patterns easily available to the user. Initially devoted to the analysis of local crystallographic texture, and as an alternative to both X-ray pole figure measurement and EBSD accessories for scanning electron microscopes, it has rapidly proven itself effective to distinguish multiple different phases contained within a given sample, including amorphous phases. Different strategies were developed to bypass the inherent limitations of transmission electron diffraction patterns, such as 180° ambiguities or the complexity of patterns produced from overlapping grains. Post processing algorithms have also been developed to improve the angular resolution and to increase the computing rate. The present paper aims to review some of these facilities. On-going works on 3D reconstruction are also introduced.

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Translation symmetries in convergent-beam electron diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100112592 ◽

1984 ◽

Vol 42 ◽

pp. 524-525

Author(s):

B. F. Buxton ◽

M. D. Shannon ◽

J. A. Eades

Keyword(s):

Electron Diffraction ◽

Perfect Crystal ◽

Convergent Beam Electron Diffraction ◽

Transmission Electron ◽

Infinite Crystal ◽

Full Symmetry ◽

The Subject ◽

Diffraction Patterns ◽

Convergent Beam ◽

The Ideal

For crystallographic studies in the transmission electron microscope the “ideal” sample is considered to be a parallel sided slab, oriented perpendicular to the electron beam, cut from perfect crystal. Such a slab does not, in general, have the full symmetry of the crystal from which it has been cut. As a result, there arises the question as to whether the symmetry observed in the diffraction pattern reflects the symmetry of the slab or that of the infinite, perfect crystal. For the most part this matter is clear but there is one class of situation that has been (and perhaps still is) the subject of some debate.If the infinite crystal contains glide planes or screw axes for which the corresponding translation is not parallel to the slab, then, strictly speaking, the slab does not have these symmetries. Normally, however, in transmission electron diffraction patterns, symmetry features that result from the presence of these symmetry elements are observed (although Goodman asserts that they should not be).

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Structure analysis of montmorillonite crystallites by convergent-beam electron diffraction

Clay Minerals ◽

10.1180/0009855054010151 ◽

2005 ◽

Vol 40 (1) ◽

pp. 1-13 ◽

Cited By ~ 15

Author(s):

T. Beermann ◽

O. Brockamp

Keyword(s):

Electron Diffraction ◽

Convergent Beam Electron Diffraction ◽

Least Square ◽

Data Set ◽

Beam Electron ◽

X Ray ◽

Kinematic Theory ◽

Vacancy Distribution ◽

Diffraction Patterns ◽

Convergent Beam

AbstractThe small particle size and the random stacking of layers has previously hindered systematic structure investigations of montmorillonite. By applying the convergent-beam electron diffraction mode (CBED) of a transmission electron microscope (TEM) with a beam spot of ~800 Å we were able to examine undisturbed areas of montmorillonite crystallites.Because montmorillonite crystallites are mostly thin particles, kinematic theory can be applied and the CBED patterns can be interpreted directly, provided that the particle thickness remains below the critical value of 350 Å. An average thickness of ~90 Å was calculated here for montmorillonite of bulk samples from X-ray diffraction analysis and lattice-fringe images. However, satisfactory diffraction intensity patterns for quantitative evaluation were obtained only from crystallites with a thickness above the average, which yielded a sufficient scattering volume. These patterns could be described in terms of the kinematic theory and therefore these crystallites were <350 Å thick. Yet, crystallites of adequate thickness were extremely rare in the three samples investigated (Clay Spur, Rock River and Upton, all in Wyoming, USA).The diffraction intensities from the ab plane of single montmorillonite crystallites of the various origins fit the three structural models for a trans-vacancy distribution, a cis-vacancy distribution or a random-cation distribution within the octahedral sheets. The configuration of the diffraction patterns also shows a 1M symmetry of the layer. Due to the limited data set of CBED patterns, a refinement of the structure could not be achieved. However, energy dispersive X-ray spectroscopy data and computation of the cation–anion distances and valences using the ‘distance valence least square’ program permitted a refinement of the models.

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Extracting Local Crystallographic Structure Using 4D-STEM Datasets

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314085441 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1455-C1455 ◽

Cited By ~ 1

Author(s):

Colin Ophus ◽

Peter Ercius ◽

Michael Sarahan ◽

Cory Czarnik ◽

Jim Ciston

Keyword(s):

Electron Diffraction ◽

Three Dimensional ◽

Convergent Beam Electron Diffraction ◽

Separate Experiment ◽

Crystallographic Structure ◽

Beam Electron ◽

Transmission Electron ◽

Scanning Transmission ◽

Diffraction Patterns ◽

Convergent Beam

Traditional scanning transmission electron microscopy (STEM) detectors are monolithic and integrate a subset of the transmitted electron beam signal scattered from each electron probe position. These convergent beam electron diffraction patterns (CBED) are extremely rich in information, containing localized information on sample structure, composition, phonon spectra, three-dimensional defect crystallography and more. Many new imaging modes become possible if the full CBED pattern is recorded at many probe positions with millisecond dwell times. In this study, we have used a Gatan K2-IS direct electron detection camera installed on an uncorrected FEI Titan-class transmission electron microscope to record 4D-STEM probe diffraction patterns on a variety of samples at up to 1600 frames per second. As an example, a 4D-STEM dataset for a multilayer stack of epitaxial SrTiO3 and mixed LaMnO3-SrTiO3 is plotted in Figure 1. Figure 1A shows a HAADF micrograph of the multilayer along a (001) zone axis. Only the A sites (Sr and La) are visible in this micrograph and the composition can be roughly determined from the relative brightness. One possible 4D-STEM technique is position-averaged convergent beam electron diffraction (PACBED) described by LeBeau et al. [1]. We can easily construct ideal PACBED patterns by averaging the probe images over each unit cell fitted from Figure 1A, which is shown in Figure 1B. By matching these patterns to PACBED images simulated with the multislice method we can precisely determine parameters such as sample thickness and composition, the latter of which is plotted in Figure 1C. For comparison, the composition has also been determined with electron energy loss spectroscopy (EELS) in a separate experiment, shown in Figure 1D. The composition range of 0-85% LaMnO3 measured by PACBED is in good agreement with the EELS measurements. In this talk we will demonstrate several other possible uses for 4D-STEM datasets.

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