Experimental and computed HREM images of the structure and defects in gadolinium silicate

1982 ◽  
Vol 15 (2) ◽  
pp. 211-215
Author(s):  
H.-U. Nissen ◽  
A. Kumao ◽  
J. Ylä-Jääski ◽  
R. Wessicken
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Rare Earth ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Image Contrast ◽  
Zone Axis ◽  
Resolution Electron ◽  
Fourier Filtering ◽  
Image Fit

Monoclinic Gd2SiO5 has been investigated by high-resolution electron microscopy (HREM) at 100 kV. Structure images are observed in the [100] and [001] projections and calculations of the image contrast using the multislice approximation are carried out to interpret the observations. For thin samples the image fit is improved by Fourier filtering of the observed images. For thicker samples the fit is found to be very sensitive to small tilt deviations of the zone axis to the electron beam. For defects observed in a fast-cooled specimen, a model in which Gd atoms replace Si atoms in segments along the (100) plane is proposed and tested by contrast calculations. These defects may be one of the reasons for deviations from stoichiometry as frequently observed in rare-earth silicates.

Hrem of Defects in Silicon at Twin Intersections

1990 ◽  
Vol 183 ◽  
Author(s):  
C. J. D. Hetherington
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Local Buckling ◽  
High Resolution Electron Microscopy ◽  
Zone Axis ◽  
Image Simulation ◽  
Lattice Image ◽  
Deformation Twins ◽  
Resolution Electron

AbstractDefects found in and around intersections of deformation twins have been examined by high resolution electron microscopy. Experimental difficulties, especially local buckling of the crystal and radiation damage under the electron beam, lead to a need to interpret images of lattices tilted by almost a degree from the zone axis. This paper demonstrates the ability of image simulation programs to model successfully the scattering from a tilted crystal. It is shown how the generation of moir6 patterns between a lattice image and a reference array of dots offers a convenient method for extracting information about distortions of the lattice around defects.

Quantitative high-resolution electron microscopy (HREM) of defects in ordered polymers

1996 ◽  
Vol 54 ◽  
pp. 166-167
Author(s):  
Patricia M. Wilson ◽  
David C. Martin
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Liquid Crystalline ◽  
High Resolution Electron Microscopy ◽  
Polymer Materials ◽  
Scattered Electron ◽  
Crystalline Polymers ◽  
Resolution Electron ◽  
Beam Damage

Efforts in our laboratory and elsewhere have established the utility of low dose high resolution electron microscopy (HREM) for imaging the microstructure of crystalline and liquid crystalline polymers. In a number of polymer systems, direct imaging of the lattice spacings by HREM has provided information about the size, shape, and relative orientation of ordered domains in these materials. However, because of the extent of disorder typical in many polymer microstructures, and because of the sensitivity of most polymer materials to electron beam damage, there have been few studies where the contrast observed in HREM images has been analyzed in a quantitative fashion.Here, we discuss two instances where quantitative information about HREM images has been used to provide new insight about the organization of crystalline polymers in the solid-state. In the first, we study the distortion of the polymer lattice planes near the core of an edge dislocation and compare these results to theories of dislocations in anisotropic and liquid crystalline solids. In the second, we investigate the variations in HREM contrast near the edge of wedge-shaped samples. The polymer used in this study was the diacetylene DCHD, which is stable to electron beam damage (Jc = 20 C/cm2) and highly crystalline. The instrument used in this work was a JEOL 4000 EX HRTEM with a beam blanidng device. More recently, the 4000 EX has been installed with instrumentation for dynamically recording scattered electron beam currents.

Atomic Scale Study of Cosi/Si (111) and CoSi2/Si (111) Interfaces

1989 ◽  
Vol 159 ◽  
Author(s):  
A. Catana ◽  
M. Heintze ◽  
P.E. Schmid ◽  
P. Stadelmann
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Orientation Relationship ◽  
Cross Sections ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Type B ◽  
Initial Stage ◽  
Resolution Electron

ABSTRACTHigh Resolution Electron Microscopy (HREM) was used to study microstructural changes related to the CoSi/Si-CoSi/CoSi2/Si-CoSi2/Si transformations. CoSi is found to grow epitaxially on Si with [111]Si // [111]CoSi and < 110 >Si // < 112 >CoSi. Two CoSi non-equivalent orientations (rotated by 180° around the substrate normal) can occur in this plane. They can be clearly distinguished by HRTEM on cross-sections ( electron beam along [110]Si). At about 500°C CoSi transforms to CoSi2. Experimental results show that the type B orientation relationship satisfying [110]Si // [112]CoSi is preserved after the initial stage of CoSi2 formation. At this stage an epitaxial CoSi/CoSi2/Si(111) system is obtained. The atomic scale investigation of the CoSi2/Si interface shows that a 7-fold coordination of the cobalt atoms is observed in both type A and type B epitaxies.

The Observation Of Mg)-Al Interface By Hrem and Microdiffraction

1985 ◽  
Vol 43 ◽  
pp. 240-241
Author(s):  
S.Y. Zhang ◽  
J.M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Materials Science ◽  
Incident Beam ◽  
High Resolution Electron Microscopy ◽  
Interface Structure ◽  
Resolution Electron ◽  
Powerful Means ◽  
Interface Structures

The combination of high resolution electron microscopy (HREM) and nanodiffraction techniques provided a powerful means for characterizing many of the interface structures which are of fundamental importance in materials science. In this work the interface structure between magnesium oxide and aluminum has been examined by HREM (with JEM-200CX) and nanodiffraction (with HB-5). The interfaces were formed by evaporating Al on freshly prepared cubic MgO smoke crystals under various vacuum conditions, at 10 -4, 10-5 10-6 and 10-7 torr. The Al layers on the MgO (001) surface are about 100Å thick. TEM observations were performed with the incident beam along the MgO [100] direction so that the interface could be revealed clearly. The nanodiffraction patterns were obtained with the electron beam of 15Å diameter parallel to the interface.

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