Moiré patterns and other crystallinity effects in the electron microscopy of polyethylene single crystals

Verhandlungen ◽  
1960 ◽  
pp. 363-367
Author(s):  
F. C. Frank ◽  
A. Keller ◽  
A. W. Agar
Keyword(s):  
Electron Microscopy ◽  
Single Crystals ◽  
Moire Patterns ◽  
Moiré Patterns

Moiré patterns in electron microscopy with atomic focuser crystals

1999 ◽  
Vol 55 (3) ◽  
pp. 533-542 ◽  
Author(s):  
J. M. Cowley ◽  
Newton Ooi ◽  
R. E. Dunin-Borkowski
Keyword(s):  
Electron Microscopy ◽  
High Resolution Imaging ◽  
Crystal Lattices ◽  
Individual Crystal ◽  
Moire Patterns ◽  
Resolution Imaging ◽  
The Individual ◽  
Thin Crystal ◽  
Moiré Patterns ◽  
Better Than

The periodic array of very fine cross-overs formed at the exit face of a thin `atomic focuser' crystal, illuminated by a parallel electron beam, may be used to form moiré patterns with a specimen crystal such that the structure of the specimen crystal may be derived with a resolution of better than 0.5 Å. Computer simulations of the moiré pattern formation have been made for the simple idealized case of two parallel gold-like lattices having a 10% difference in lattice constant. Moiré images are shown for the case of a small objective aperture in the viewing electron microscope such that the individual crystal lattices are not resolved and for a larger objective aperture for which the individual crystal lattices are resolved and the intensity is measured at the positions of the atoms of the atomic focuser crystal. The latter case confirms the viability of the scheme for ultra-high-resolution imaging of general specimens by use of a thin-crystal periodic atomic focuser, as previously proposed.

Moire Patterns in High Resolution Electron Microscopy Images

1994 ◽  
Vol 332 ◽  
Author(s):  
J. Reyes—Gasga ◽  
S. Tehuacanero ◽  
C. Zorrilla
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Atomic Structure ◽  
Computer Graphic ◽  
High Resolution Electron Microscopy ◽  
Direct Image ◽  
Resolution Electron ◽  
Moire Patterns ◽  
Microscopy Images ◽  
Moiré Patterns

ABSTRACTMoiré patterns are so often observed in the HREM images and they could be mistaken as the direct image of the atomic structure of the sample under analysis. In this workwe presented some examples of these patterns and their computer graphic simulations.

Features of moiré patterns in HPHT-grown diamond single crystals

2002 ◽  
Vol 52 (3) ◽  
pp. 187-191
Author(s):  
Long-Wei Yin ◽  
Mu-Sen Li ◽  
Dong-Sheng Sunm ◽  
Zeng-Da Zou ◽  
Yu-Xian Liu ◽  
...  
Keyword(s):  
Single Crystals ◽  
Moire Patterns ◽  
Diamond Single Crystals ◽  
Moiré Patterns

Moire Fringes on Precipitates in Quenched and Aged Beryllium

1968 ◽  
Vol 26 ◽  
pp. 426-427
Author(s):  
F. J. Fraikor ◽  
A. W. Brewer
Keyword(s):  
Ternary Phase ◽  
Volume Fraction ◽  
Age Hardening ◽  
Orientation Relationships ◽  
Solute Content ◽  
Moiré Fringes ◽  
Moire Patterns ◽  
Total Volume Fraction ◽  
Diffraction Patterns ◽  
Moiré Patterns

A number of investigators have examined moire patterns on precipitate particles in various age-hardening alloys. For example, Phillips has analyzed moire fringes at cobalt precipitates in copper and Von Heimendahl has reported on moire fringes in the system Al-Au. Recently, we have observed moire patterns on impurity precipitates in beryllium quenched in brine from 1000°C and aged at various temperatures in the range of 500-800°C. This heat treatment of beryllium rolled from vacuum cast ingots produces the precipitation of both an fee ternary phase, AlFeBe4, and an hcp binary phase, FeBe11. However, unlike a typical age-hardening alloy, the solute content of this material is low (less than 1000 ppm of Fe and 600 ppm of Al) and hence the total volume fraction of precipitates is small. Therefore there is some difficulty in distinguishing the precipitates and their orientation relationships with the beryllium matrix since the weak precipitate spots generally do not appear on the diffraction patterns.

Transmission Electron Microscopy study of Bi-based superconducting phases

1990 ◽  
Vol 48 (4) ◽  
pp. 50-51
Author(s):  
J.G. Wen ◽  
K.K. Fung
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Space Groups ◽  
Superconducting Phases ◽  
Ceramic Samples ◽  
Transmission Electron ◽  
Modulated Structures

Bi-based superconducting phases have been found to be members of a structural series represented by Bi2Sr2Can−1Cun−1On+4, n=1,2,3, and are referred to as 2201, 2212, 2223 phases. All these phases are incommensurate modulated structures. The super space groups are P2/b, NBbmb 2201, 2212 phases respectively. Pb-doped ceramic samples and single crystals and Y-doped single crystals have been studied by transmission electron microscopy.Modulated structures of all Bi-based superconducting phases are in b-c plane, therefore, it is the best way to determine modulated structure and c parameter in diffraction pattern. FIG. 1,2,3 show diffraction patterns of three kinds of modulations in Pb-doped ceramic samples. Energy dispersive X-ray analysis (EDAX) confirms the presence of Pb in the three modulated structures. Parameters c are 3 0.06, 38.29, 30.24Å, ie 2212, 2223, 2212 phases for FIG. 1,2,3 respectively. Their average space groups are all Bbmb.

Imaging of polymer single crystals in low-voltage, high-resolution scanning electron microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 1106-1107
Author(s):  
W.W. Adams ◽  
G. Price ◽  
A. Krause
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Single Crystals ◽  
Low Voltage ◽  
Polymer Surface ◽  
Beam Current ◽  
Image Features ◽  
First Results ◽  
Scanning Electron

It has been shown that there are numerous advantages in imaging both coated and uncoated polymers in scanning electron microscopy (SEM) at low voltages (LV) from 0.5 to 2.0 keV compared to imaging at conventional voltages of 10 to 20 keV. The disadvantages of LVSEM of degraded resolution and decreased beam current have been overcome with the new generation of field emission gun SEMs. In imaging metal coated polymers in LVSEM beam damage is reduced, contrast is improved, and charging from irregularly shaped features (which may be unevenly coated) is reduced or eliminated. Imaging uncoated polymers in LVSEM allows direct observation of the surface with little or no charging and with no alterations of surface features from the metal coating process required for higher voltage imaging. This is particularly important for high resolution (HR) studies of polymers where it is desired to image features 1 to 10 nm in size. Metal sputter coating techniques produce a 10 - 20 nm film that has its own texture which can obscure topographical features of the original polymer surface. In examining thin, uncoated insulating samples on a conducting substrate at low voltages the effect of sample-beam interactions on image formation and resolution will differ significantly from the effect at higher accelerating voltages. We discuss here sample-beam interactions in single crystals on conducting substrates at low voltages and also present the first results on HRSEM of single crystal morphologies which show some of these effects.

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