Applications of Convergent Beam Electron Diffraction to the Study of Precipitate Structure

1981 ◽  
Vol 39 ◽  
pp. 352-353 ◽  
Author(s):  
M.P. Shaw ◽  
A.J. Pcrter ◽  
R.C. Ecob ◽  
B. Ralph
Keyword(s):  
Electron Diffraction ◽  
Convergent Beam Electron Diffraction ◽  
Nickel Base Superalloy ◽  
Beam Electron ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Nickel Base ◽  
Convergent Beam ◽  
Local Crystal Structure ◽  
Base Superalloy

Convergent Beam Electron Diffraction (CBED) is a technique that has become widely available in recent years with the advent of modern analytical transmission electron microscopes designed to allow the formation of small electron probes on the specimen surface. It can be used in a number of ways to investigate local crystal structure (see e.g. 1) and is complementary to the analytical information obtainable from spectroscopic accessories. The specific application discussed in the present paper involves the use of high order Laue zone (holz) lines, which form part of the fine structure within individual discs in the diffraction pattern. These have been used to investigate small symmetry variations accompanying changes in ordering of γ' precipitates in a nickel base superalloy (Udimet 720) (e.g. 2,3). Examination is made of the symmetry associated with holz patterns from suitably related crystallographic poles, and these are compared with computer simulated patterns in order to establish unit cell shape and symmetry.

Convergent-beam electron diffraction at high spatial resolution

1992 ◽  
Vol 50 (2) ◽  
pp. 1152-1153 ◽  
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.

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.

Plan-View CBED Studies of Nio-Zro2(CaO) Interfaces

1989 ◽  
Vol 159 ◽  
Author(s):  
V.P. Dravid ◽  
M.R. Notis ◽  
C.E. Lyman ◽  
A. Revcolevschi
Keyword(s):  
Electron Diffraction ◽  
Convergent Beam Electron Diffraction ◽  
Low Energy ◽  
Directionally Solidified ◽  
Plan View ◽  
Beam Electron ◽  
Transmission Electron ◽  
Interfacial Defects ◽  
Convergent Beam ◽  
Lamellar Interfaces

ABSTRACTLow energy lamellar interfaces in the directionally solidified eutectic (DSE) NiO-ZrO2(CaO) have been investigated using transmission electron diffraction and imaging. The symmetry of this bicrystal and an aspect of interfacial relaxations in the form of symmetry lowering in-plane rigid body translation (RBT) have been explored by performing convergent beam electron diffraction (CBED) experiments of plan-view bicrystals. Edge-on interfaces have also been studied by conventional and high resolution transmission electron microscopy (CTEM and HRTEM respectively), and electron diffraction fine structure analysis. Despite certain experimental difficulties due to interfacial defects and strain, plan-view CBED patterns offered valuable information concerning bicrystal symmetry and indicated no symmetry lowering RBT in this bicrystal. The suitability of plan-view CBED is briefly discussed in view of its potential as a technique to determine bicrystal symmetry and RBT.

Characterization Of APB's In GaP

1996 ◽  
Vol 442 ◽  
Author(s):  
Dov Cohen ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Convergent Beam Electron Diffraction ◽  
Antiphase Boundaries ◽  
Beam Electron ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Crystallographic Orientations

AbstractAntiphase boundaries in GaP crystals epitactically grown on Si (001) have been characterized using transmission electron microscopy. Convergent-beam electron diffraction was used to identify the antiphase-related grains. The antiphase boundaries were observed to adopt facets parallel to specific crystallographic orientations. Furthermore, stacking-fault-like contrast was observed along the interface suggesting that the domains may be offset from one another by a rigid-body lattice translation.

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

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.

Advantages of FE-TEM for convergent-beam electron diffraction

1993 ◽  
Vol 51 ◽  
pp. 1206-1207
Author(s):  
T. Kaneyama ◽  
T. Tomita ◽  
Y. Ishida ◽  
M. Kersker
Keyword(s):  
Electron Diffraction ◽  
Spatial Resolution ◽  
Convergent Beam Electron Diffraction ◽  
Lens System ◽  
Beam Electron ◽  
X Ray ◽  
Small Probe ◽  
Electron Microscopes ◽  
Convergent Beam ◽  
Electron Energy Loss

Many electron microscopes equipped with a field-emission gun (FE-TEMs) are now used for the purpose of improving the spatial and the energy resolution in energy dispersive x-ray spectroscopy and electron energy loss spectroscopy. For the convergent-beam electron diffraction techniques, FE-TEMs have greater advantages than conventional electron microscopes with a thermal LaB cathode. We discussed these advantages using JEM2010F and JEM2010, which have equivalent specifications except for the electron source and the condenser lens system.High spatial resolutionThe brightness of an FE-gun (∽ 5 × 108A cm-2 sr-1) is about 100 times that a conventional LaB6 cathode. The gun can obtain enough current for taking CBED patterns in an exposure time of a few seconds even with an electron probe less than 1 nm in diameter (FIG. 1). Steep wedge shapes and rapid bends within the illuminated area deteriorate the accuracy of quantitative CBED analysis. Improvement of the spatial resolution by a small probe reduces these inevitable averaging effects.

scholarly journals Dislocation Analysis in SiGe Heterostructures by Large-Angle Convergent Beam Electron Diffraction

Crystals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Heiko Groiss
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Strain Relaxation ◽  
Large Angle ◽  
Convergent Beam Electron Diffraction ◽  
Self Organization ◽  
Detailed Knowledge ◽  
Beam Electron ◽  
Transmission Electron ◽  
Convergent Beam

Dislocations play a crucial role in self-organization and strain relaxation mechanisms in SiGe heterostructures. In most cases, they should be avoided, and different strategies exist to exploit their nucleation properties in order to manipulate their position. In either case, detailed knowledge about their exact Burgers vectors and possible dislocation reactions are necessary to optimize the fabrication processes and the properties of SiGe materials. In this review a brief overview of the dislocation mechanisms in the SiGe system is given. The method of choice for dislocation characterization is transmission electron microscopy. In particular, the article provides a detailed introduction into large-angle convergent-beam electron diffraction, and gives an overview of different application examples of this method on SiGe structures and related systems.

The Art and Application of Large Angle Convergent Beam Electron Diffraction

2012 ◽  
Vol 186 ◽  
pp. 16-19 ◽  
Author(s):  
Elżbieta Jezierska
Keyword(s):  
Electron Diffraction ◽  
Large Angle ◽  
Antiphase Boundary ◽  
Antiphase Domain ◽  
Dark Field ◽  
Convergent Beam Electron Diffraction ◽  
Intermetallic Alloys ◽  
Beam Electron ◽  
Transmission Electron ◽  
Convergent Beam

The antiphase domain structure in Ni3Al and Al3Ti+Cu intermetallic alloys was recognized by conventional transmission electron microscopy and large angle convergent beam electron diffraction methods. In the case of antiphase boundary the superlattice excess line is split into two lines with equal intensity on bright and dark field LACBED pattern. This splitting can be considered as typical and used to identify APBs. The recognition between perfect structure of the defect-free matrix and the screw deviation around the nanopipes in GaN epilayers was performed with high accuracy using Zone Axis LACBED images.

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