Anisotropic radiation damage of potassium tetracyano platinate (KCP)

1978 ◽  
Vol 36 (1) ◽  
pp. 392-393
Author(s):  
N. Uyeda ◽  
E. J. Kirkland ◽  
B. M. Siegel
Keyword(s):  
Electron Diffraction ◽  
Radiation Damage ◽  
Structural Changes ◽  
High Resolution Electron Microscopy ◽  
Radiation Sensitivity ◽  
Resolution Electron ◽  
Damage Process ◽  
Diffraction Patterns ◽  
Fading Rate

The direct observation of structural change by high resolution electron microscopy will be essential for the better understanding of the damage process and its mechanism. However, this approach still involves some difficulty in quantitative interpretation mostly being due to the quality of obtained images. Electron diffraction, using crystalline specimens, has been the method most frequently applied to obtain a comparison of radiation sensitivity of various materials on the quantitative base. If a series of single crystal patterns are obtained the fading rate of reflections during the damage process give good comparative measures. The electron diffraction patterns also render useful information concerning the structural changes in the crystal. In the present work, the radiation damage of potassium tetracyano-platinate was dealt with on the basis two dimensional observation of fading rates of diffraction spots. KCP is known as an ionic crystal which possesses “one dimensional” electronic properties and it would be of great interest to know if radiation damage proceeds in a strongly asymmetric manner.

Atomic structure of YB56 studied by digital high-resolution electron microscopy and electron diffraction

2001 ◽  
Vol 16 (1) ◽  
pp. 101-107 ◽  
Author(s):  
Takeo Oku ◽  
Jan-Olov Bovin ◽  
Iwami Higashi ◽  
Takaho Tanaka ◽  
Yoshio Ishizawa
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Charge Coupled Device ◽  
X Ray ◽  
Resolution Electron ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Simulated Images

Atomic positions for Y atoms were determined by using high-resolution electron microscopy and electron diffraction. A slow-scan charge-coupled device camera which had high linearity and electron sensitivity was used to record high-resolution images and electron diffraction patterns digitally. Crystallographic image processing was applied for image analysis, which provided more accurate, averaged Y atom positions. In addition, atomic disordering positions in YB56 were detected from the differential images between observed and simulated images based on x-ray data, which were B24 clusters around the Y-holes. The present work indicates that the structure analysis combined with digital high-resolution electron microscopy, electron diffraction, and differential images is useful for the evaluation of atomic positions and disordering in the boron-based crystals.

Small-Spot Illumination For High-Resolution Electron Microscopy of Beam-Sensitive Specimens

1985 ◽  
Vol 43 ◽  
pp. 320-321
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Photographic Emulsion ◽  
Lateral Motion ◽  
Small Spot ◽  
Resolution Electron ◽  
Diffraction Patterns

The contrast observed in images of beam-sensitive, crystalline specimens is found to be significantly less than one would predict based on observations of electron diffraction patterns of the specimens. Factors such as finite coherence, inelastic scattering, and the limited MTF of the photographic emulsion account for some decrease in contrast. It appears, however, that most of the loss in signal is caused by motion of the specimen during exposure to the electron beam. The introduction of point and other defects in the crystal, resulting from radiation damage, causes bending and lateral motion, which degrade the contrast in the image. We have therefore sought to determine whether the beam-induced specimen motion can be reduced by reducing the area of the specimen which is illuminated at any one time.

On the interpretation of electron diffraction patterns from materials containing planar boundaries: the intergrowth tungsten bronzes

1990 ◽  
Vol 429 (1876) ◽  
pp. 91-117 ◽  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
General Interest ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Resolution Imaging ◽  
Diffraction Patterns

Materials containing planar boundaries are of general interest and complete understanding of their structures is important. When direct imaging of the boundaries by, for instance, high-resolution electron microscopy, is impracticable, details of their structure and arrangement may be obtained from electron diffraction patterns. Such patterns are discussed in terms of those from intergrowth tungsten bronzes as specific examples. Fourier-transform calculations for proposed structures have been made to establish, in conjunction with optical-diffraction analogues, the features of the far-field diffraction patterns. These results have been compared with diffraction patterns obtained experimentally by transmission electron microscopy. The aim of the study, to show that the arrangement of the boundaries in these complicated phases can be deduced from their diffraction patterns without the need for high-resolution imaging, has been achieved. The steps to be taken to make these deductions are set out.

Application of the imaging plate to quantitative analysis of electron-diffraction and high-resolution electron microscopy

1989 ◽  
Vol 47 ◽  
pp. 666-667
Author(s):  
K. Hiraga ◽  
D. Shindo ◽  
M. Hirabayashi ◽  
T. Oikawa ◽  
N. Mori ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Quantitative Analysis ◽  
High Resolution ◽  
Electron Diffraction ◽  
Electron Micrographs ◽  
High Resolution Electron Microscopy ◽  
Imaging Plate ◽  
Resolution Electron ◽  
Diffraction Patterns ◽  
High Resolution Electron Micrographs

The “Imaging Plate” (IP) has three superior characteristics, i.e., high sensitivity to the electron beam, and a wide dynamic range and good linearity for electron dose compared with conventional EM films. The use of the IP is expected to lead to quantitative analysis of electron microscopy. The purpose of the present work is to examine the possibility of application of the IP to the quantitative analysis of electron diffraction and high-resolution electron microscopy.By using the TEM-IP System developed by Oikawa et al., which is published in this conference, electron diffraction patterns and high-resolution electron micrographs taken on the IP with an effective size of 102 х 77 mm2 were convertedinto digital data of 2048 х 1536 pixels with 4096 gray levels. Observations of electron diffraction patterns and high-resolution electron micrographs were made with a 200 kV (JEM-2000FX) and a 400 kV (JEM-4000EX) electron microscope, respectively.

Ordered structure formation in the flux-grown Ba(Mg1/3Ta2/3)O3 single crystals

2001 ◽  
Vol 16 (6) ◽  
pp. 1593-1599 ◽  
Author(s):  
Yu-Chang Lee ◽  
Chen-Chia Chou ◽  
Dah-Shyang Tsai
Keyword(s):  
Electron Diffraction ◽  
Single Crystals ◽  
Annealing Time ◽  
High Resolution Electron Microscopy ◽  
Maximum Intensity ◽  
Ordered Structure ◽  
X Ray Diffraction ◽  
Resolution Electron ◽  
Higher Temperature ◽  
Diffraction Patterns

Formation of ordered structure in flux-grown Ba(Mg1/3Ta2/3)O3(BMT) single crystals was studied using x-ray diffraction, electron diffraction, and high-resolution electron microscopy. The low-temperature-grown crystals exhibited no sign of B-site ordering. Annealing at 1500 °C induced the 1:2 ordered phase, and its content increased with the annealing time. The superlattice diffraction peaks were broad initially; they sharpened rapidly with the annealing time. Diffuse superlattice reflections were found in electron diffraction patterns of 1500 °C annealed BMT; they turned into sharp reflections under long annealing time or higher temperature, 1600 °C. The intensity of diffuse reflections was sparsely distributed, but the maximum intensity location was determined in the digitized recording of image plate. The maximum intensity sites of two diffuse reflections in the 〈111〉 direction deviated from the presumed 1/3 and 2/3 positions and shifted towards the center. The diffuse reflection and the deviation from regular positions were interpreted as the composition modulation during B-site cation diffusion.

Can The Icosahedral Phase Be Modeled as a Crystal?

1996 ◽  
Vol 54 ◽  
pp. 716-717
Author(s):  
Weimin Bian ◽  
Yimei Zhu
Keyword(s):  
Electron Diffraction ◽  
Orientational Order ◽  
Point Group ◽  
High Resolution Electron Microscopy ◽  
Icosahedral Phase ◽  
Unit Cell ◽  
Fivefold Symmetry ◽  
Resolution Electron ◽  
Crystal Model ◽  
Diffraction Patterns

We propose a crystal model that is in excellent agreement with the experimental electron diffraction patterns and high-resolution electron microscopy images of the icosahedral phase in Mn-Al and related systems. Structurally, the model has long-range translational order with a large unit-cell (Im3 space group) containing 10038 atoms, as well as orientational order characterized by symmetry close to the m35 point group which is commonly assigned for quasicrystals.Fig.l(a)-(c) show, respectively, the SAD patterns of the so-called twofold, threefold, and fivefold axes observed in rapid quenched Al-14at%Mn. Simulation of the corresponding SAD patterns (Fig.l(d)-(h)) suggested that they did not result from a single zone-axis diffraction, but from several closely orientated zone axes. For example, Fig.1(f) was generated by the superposition of the [305], [508], and [8 0 13],…. axes (denoted as N-<305>); the rotation angles from the [001] axis to each axis are 30.96°, 32.01°, and 31.61 °, respectively. All are very close to 31.71 °, which is the angle between a twofold and a fivefold axis in the m35 point group. In a conventional electron diffraction experiment, if the [001] axis of the crystal is rotated 31.71° around the [010] axis, these three zone axes would simultaneously satisfy the Bragg conditions and cannot be separated. Such superposition in the projected diffraction pattern, especially when the unit-cell is large, can yield a pseudo-fivefold symmetry which is indistinguishable with a true fivefold symmetry in SAD.

Plan-view microstructures of Co/Ru bilayers

1995 ◽  
Vol 10 (6) ◽  
pp. 1539-1545 ◽  
Author(s):  
G.Z. Pan ◽  
A. Michel ◽  
V. Pierron-Bohnes ◽  
P. Vennéguès ◽  
M.C. Cadeville
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Image Contrast ◽  
Misfit Dislocations ◽  
Double Diffraction ◽  
Plan View ◽  
Resolution Electron ◽  
Diffraction Patterns

Plan-view microstructures of two Co/Ru bilayers with a composition of [Co12ÅRu45Å]2 and [Co40ÅRu35Å]2 have been studied by conventional and high resolution electron microscopy. Large differences in electron diffraction and image contrast between the two bilayers were observed, which are recognized as the microstructural variations during the relaxation of large coherent planar strains when the Co layers wet coherently or semicoherently the Ru layers. For the [Co12ÅRu45Å]2 bilayer, the Co layers are unrelaxed from the Ru layers; only one set of electron diffraction patterns was observed, and the image consists of three types of contrasts which are closely related with either the generation and movement of misfit dislocations or large coherent strains. For the [Co40ÅRu35Å]2 bilayer, the Co layers are relaxed basically from the Ru layers; two sets of electron diffraction patterns with double diffraction spots were observed, and the image consists of small irregular areas with moiré fringe dots.

Modulated Structure of Bi1.8Sr2.0Rh1.6Ox

2007 ◽  
Vol 336-338 ◽  
pp. 818-821
Author(s):  
Kunio Yubuta ◽  
Satoshi Okada ◽  
Yuzuru Miyazaki ◽  
Ichiro Terasaki ◽  
Tsuyoshi Kajitani
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Layered Crystal ◽  
Structural Analogue ◽  
Modulated Structure ◽  
Incident Electron Beam ◽  
Resolution Electron ◽  
High Resolution Images ◽  
Diffraction Patterns

We have investigated the modulated structure of the misfit-layered crystal Bi1.8Sr2.0Rh1.6Ox by means of electron diffraction and high-resolution electron microscopy. This compound consists of two interpenetrating subsystems of a hexagonal RhO2 sheet and a distorted four-layered rock-salt-type (Bi,Sr)O block. Both subsystems have common a-, c-axes and β-angles with a = 5.28 Å, c = 29.77 Å and β = 93.7º. On the other hand, the crystal structure is incommensurated parallel to the b-axes, among which b1 = 3.07 Å for the RhO2 sheet and b2 = 4.88 Å for the (Bi,Sr)O block. The misfit ratio, b1/b2 ~ 0.63, characterizes the structural analogue as [Bi1.79Sr1.98Oy]0.63[RhO2]. This compound has two modulation vectors, i.e., q1 = – a* + 0.63b1* and q2 = 0.17b1* + c*, and the superspace group is assigned as the Cc(1β0, 0μ1)-type from the electron diffraction patterns. High-resolution images taken with the incident electron beam parallel to the a- and c-axes clearly show displacive as well as compositional modulations.

High Resolution Electron Microscopy and Electron Diffraction of YBa2Cu3O7−x

1987 ◽  
Vol 99 ◽  
Author(s):  
William Krakow ◽  
Thomas M. Shaw
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Oxygen Vacancies ◽  
Computer Experiments ◽  
High Resolution Electron Microscopy ◽  
Simulation Experiments ◽  
Resolution Electron ◽  
Short Range Ordering ◽  
Diffraction Patterns ◽  
High Resolution Electron Micrographs

ABSTRACTExperimental high resolution electron micrographs and computer simulation experiments have been used to evaluate the visibility of the atomic constituents of YBa2Cu3O7−x. In practice, the detection of oxygen has not been possible in contradiction to that predicted by modelling of perfect crystalline material. Preliminary computer experiments of the electron diffraction patterns when oxygen vacancies are introduced on the Cu-O sheets separating Ba layers show the diffuse streaks characteristic of short range ordering.

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