Disappearance Voltage Determinations Using a Convergent Beam

1971 ◽  
Vol 29 ◽  
pp. 184-185
Author(s):  
W. L. Bell
Keyword(s):  
Second Order ◽  
Objective Method ◽  
Uniform Thickness ◽  
Rocking Curve ◽  
Crystal Perfection ◽  
Kikuchi Line ◽  
Central Maximum ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

On the role of the second-order derivative term in the calculation of convergent beam diffraction patterns

2017 ◽  
Vol 179 ◽  
pp. 73-80 ◽  
Author(s):  
S.C. Hillier ◽  
E.T. Robertson ◽  
G.D. Reid ◽  
R.D. Haynes ◽  
M.D. Robertson
Keyword(s):  
Second Order ◽  
Order Derivative ◽  
Derivative Term ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Convergent Beam Diffraction

Diffraction Patterns Obtained by Scanning Electron Microscope

1972 ◽  
Vol 27 (3) ◽  
pp. 441-444d ◽  
Author(s):  
F Fujimoto ◽  
K Komaki ◽  
S Takagi ◽  
H Koike
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Incident Beam ◽  
Reciprocal Theorem ◽  
Diffraction Patterns ◽  
The Reciprocal Theorem ◽  
Convergent Beam ◽  
Beam Technique ◽  
Transmission Scanning Electron Microscopy ◽  
Scanning Electron

AbstractKossel-Möllenstedt and Kikuchi patterns are obtained by transmission scanning electron microscopy and compared with those obtained by the convergent beam technique from the same portion of the specimen. The identity of corresponding patterns obtained by both techniques shows the validity of the reciprocal theorem in electron diffraction for both elastic and inelastic scattering. The variations of Kossel-Möllenstedt patterns with the conditions of the incident beam and the position of the detector are also shown.

Relative Intensities in ED Patterns From Thin Gold Films

1972 ◽  
Vol 30 ◽  
pp. 636-637
Author(s):  
R. H. Morriss ◽  
J. D. C. Peng ◽  
C. D. Melvin
Keyword(s):  
Theoretical Calculations ◽  
Diffraction Theory ◽  
Gold Films ◽  
Reasonable Accuracy ◽  
Experimental Conditions ◽  
Crystal Perfection ◽  
Heavy Atoms ◽  
Fine Focus ◽  
Convergent Beam ◽  
Beam Diffraction

Although dynamical diffraction theory was modified for electrons by Bethe in 1928, relatively few calculations have been carried out because of computational difficulties. Even fewer attempts have been made to correlate experimental data with theoretical calculations. The experimental conditions are indeed stringent - not only is a knowledge of crystal perfection, morphology, and orientation necessary, but other factors such as specimen contamination are important and must be carefully controlled. The experimental method of fine-focus convergent-beam electron diffraction has been successfully applied by Goodman and Lehmpfuhl to single crystals of MgO containing light atoms and more recently by Lynch to single crystalline (111) gold films which contain heavy atoms. In both experiments intensity distributions were calculated using the multislice method of n-beam diffraction theory. In order to obtain reasonable accuracy Lynch found it necessary to include 139 beams in the calculations for gold with all but 43 corresponding to beams out of the [111] zone.

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.

Identification by Electron Microdiffraction of Intermetallic Phases in a Duplex Stainless Steel

1990 ◽  
Vol 48 (2) ◽  
pp. 494-495
Author(s):  
A. Redjaïmia ◽  
J.P. Morniroli ◽  
G. Metauer ◽  
M. Gantois
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Convergent Beam Electron Diffraction ◽  
Intermetallic Phases ◽  
Small Particles ◽  
Parallel Beam ◽  
Diffraction Patterns ◽  
Average Size ◽  
Convergent Beam ◽  
Electron Microdiffraction

2D and especially 3D symmetry information required to determine the crystal structure of four intermetallic phases present as small particles (average size in the range 100-500nm) in a Fe.22Cr.5Ni.3Mo.0.03C duplex stainless steel is not present in most Convergent Beam Electron Diffraction (CBED) patterns. Nevertheless it is possible to deduce many crystal features and to identify unambiguously these four phases by means of microdiffraction patterns obtained with a nearly parallel beam focused on a very small area (50-100nm).From examinations of the whole pattern reduced (RS) and full (FS) symmetries the 7 crystal systems and the 11 Laue classes are distinguished without ambiguity (1). By considering the shifts and the periodicity differences between the ZOLZ and FOLZ reflection nets on specific Zone Axis Patterns (ZAP) which depend on the crystal system, the centering type of the cell and the glide planes are simultaneously identified (2). This identification is easily done by comparisons with the corresponding simulated diffraction patterns.

Computer-Aided Analysis of Oriented Crystallites by Diffraction Pattern Simulation and Tilt-Stage Control in a TEM

1997 ◽  
Vol 3 (S2) ◽  
pp. 1015-1016
Author(s):  
L.E. Thomas ◽  
L.A. Chariot ◽  
J.T. Stanley
Keyword(s):  
Small Sample ◽  
Hot Water ◽  
Metal Corrosion ◽  
Desktop Computer ◽  
Cross Sectional ◽  
Surface Corrosion ◽  
Computer Aided ◽  
Columnar Grains ◽  
Diffraction Patterns ◽  
Convergent Beam

Electron diffraction patterns taken in the transmission electron microscope (TEM) provide information about crystal structures and orientations in small sample areas. Extracting this information and manipulating local crystal orientations has become a great deal easier with the availability of desktop computer programs that allow simulation matching of experimental patterns and crystallographic control of sample tilting in the TEM. This presentation will illustrate an application of computer-aided crystallography for analyzing oriented crystallites in an experimentally complex material.The surface corrosion films that form on reactive metals such as hafnium or zirconium in hot water provided our example. Cross-sectional examinations of the corrosion films revealed a columnar microstructure of monoclinic HfO2/ZrO2 grains extending normal to the metal/corrosion-film interface.The columnar grains were only about 50 nm in width, and thus were too small to analyze individually by selected-area diffraction. Local strains in the films smeared the diffraction fine structure so there was little hope for analysis by convergent-beam diffraction methods.

DIFFRACTION STUDIES OF METAL-SEMICONDUCTOR INTERFACES

1985 ◽  
Vol 56 ◽  
Author(s):  
D. CHERNS ◽  
C.J. KIELY
Keyword(s):  
Convergent Beam Electron Diffraction ◽  
Wide Angle ◽  
Plan View ◽  
Beam Electron ◽  
Semiconductor Interfaces ◽  
Gaas Films ◽  
Rigid Body Displacement ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Sensitive Method

AbstractThe use of convergent beam electron diffraction patterns (CBPs) for investigating metal—semiconductor interfaces in plan—view samples is considered. It is shown that a wide—angle diffraction technique provides a sensitive method of measuring tetragonal distortions in NiSi 2/(001)Si bicrystals. A study of CBP symmetry and the detailec branch structure in higher order Laue zone rings has enabled the interfacial rigid body displacement in NiSi 2/(001)Si and Al/(001)GaAs films to be determined.

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