Quantitative Electron Microscope with imaging plate

1994 ◽  
Vol 52 ◽  
pp. 408-409
Author(s):  
D. Shindo
Keyword(s):  
Electron Microscope ◽  
Dynamic Range ◽  
Processing System ◽  
Digital Data ◽  
Imaging Plate ◽  
Crystal Thickness ◽  
X Ray Diffraction ◽  
Resolution Electron ◽  
Electron Intensity ◽  
Diffraction Patterns

Imaging plate has good properties, i.e., a wide dynamic range and good linearity for the electron intensity. Thus the digital data (2048x1536 pixels, 4096 gray levels in log scale) obtained with the imaging plate can be used for quantification in electron microscopy. By using the image processing system (PIXsysTEM) combined with a main frame (ACOS3900), quantitative analysis of electron diffraction patterns and high-resolution electron microscope (HREM) images has been successfully carried out.In the analysis of HREM images observed with the imaging plate, quantitative comparison between observed intensity and calculated intensity can be carried out by taking into account the experimental parameters such as crystal thickness and defocus value. An example of HREM images of quenched Tl2Ba2Cu1Oy (Tc = 70K) observed with the imaging plate is shown in Figs. 1(b) - (d) comparing with a structure model proposed by x-ray diffraction study of Fig. 1 (a). The image was observed with a JEM-4000EX electron microscope (Cs =1.0 mm).

Quantification of High Resolution Electron Microscopy and Electron Diffraction by the Imaging Plate

1990 ◽  
Vol 48 (1) ◽  
pp. 172-173
Author(s):  
Daisuke Shindo ◽  
Kenji Hiraga ◽  
Makoto Hirabayashi ◽  
Tetsuo Oikawa ◽  
Nobufumi Mori
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Dynamic Range ◽  
Processing System ◽  
Digital Data ◽  
Imaging Plate ◽  
Diffraction Effect ◽  
Hrem Image ◽  
Large Computer ◽  
Resolution Electron

Taking advantages of “Imaging Plate” (IP), i.e., a wide dynamic range and good linearity for electron intensity, high resolution electron microscope (HREM) images and electron diffraction (ED) patterns were quantitatively investigated. Observations of HREM images and ED patterns were made by the TEM-IP System (PIXsys TEM) using electron microscopes JEM-4000EX and JEM-2000FX, respectively. The data on the IP with an effective size of 102×77 mm2 was converted into digital data of 2048 × 1536 pixels with 4096 gray levels and analyzed with the IP-processor of the PIXsys TEM and a large-computer ACOS-2020.Since the IP is highly sensitive to incident electrons, the beam convergence can be lowered for HREM observations, and so the effect of the dumping envelope due to the beam divergence can be reduced. In Fig. 1, an HREM image of an oxide W-Ta-O, taken at a direct magnification of 1,500,000x and an exposure time of 2 s, shows fine contrast of partially ordered cation distributions. Although the phase contrast of the HREM image is rather weak, the image was recorded with about 1100 effective gray levels which are much larger than the 256 gray levels normally used in a conventional image processing system. Intensity distributions in two parts of the image near the crystal edge (A) and at a relatively thicker region (B) are visualized with perspective drawings in Figs. 2(a) and 2(b), and compared quantitatively with contour maps in Figs. 3(a) and 3(b), respectively. It was noticed that projected atomic potentials of the block structure unit (see the inset of Fig. 1) were revealed faithfully in A, having intensity minima at heavy atomic columns (H), whereas the low potential regions (L) have sharp intensity maxima at the thicker region B. These observed images will be compared quantitatively with calculated ones, taking into account the dynamical diffraction effect.

Quantitative analysis of diffuse scattering with imaging plate

1992 ◽  
Vol 50 (2) ◽  
pp. 1188-1189
Author(s):  
D. Shindo ◽  
T. Ohishi ◽  
S. Iijima ◽  
K. Hiraga ◽  
T. Oikawa ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Quantitative Analysis ◽  
Electron Diffraction ◽  
Diffuse Scattering ◽  
Dynamic Range ◽  
Imaging Plate ◽  
Diffraction Effect ◽  
Electron Intensity ◽  
Diffraction Patterns ◽  
Dynamical Factor

The excellent properties of the imaging plate (IP), i.e., a wide dynamic range and good linearity for the electron intensity, are promising for quantitative analysis of diffuse scattering since they allow a small dynamical diffraction effect to be evaluated with ‘dynamical factor’. In this paper, we first present accurate measurement of thermal diffuse scattering (TDS), which contributes dominantly to the background of electron diffraction patterns. Secondly, we present a method of extracting weak signal scattering intensities from the background, and apply it to the analysis of diffuse scattering caused from short-range ordered structures.Electron microscope images were obtained with a JEM-2000EXII electron microscope. Image processing was carried out by using a computer system (ACOS 2020) at Tohoku University. Electron diffraction patterns were recorded by using the TEM-IP system (PIXsysTEM). The details of the IP data handling were presented in the previous paper.Figure 1 shows an electron diffraction pattern obtained from an Au thin film ( t ∼ 40nm) at room temperature.

Crystal Structures Of L-Nb205 AND L-Ta205

1977 ◽  
Vol 35 ◽  
pp. 188-189
Author(s):  
Sumio Iijima
Keyword(s):  
Electron Microscope ◽  
Complex Nature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resolution Electron ◽  
Unit Cells ◽  
System 2 ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Phase Relationships

Although structures of tantalum pentoxides have been extensively studied, they have not been fully understood because of the complex nature of their X-ray diffraction patterns. In this study we made some observations on crystals of L-Ta2O5 and L-Nb2O5 using a high resolution electron microscope. The latter structure has been believed to be isostructural with L-Ta2O5. The samples were prepared by Dr. Roth at NBS and were parts of the products used for determining phase relationships in niobium pentoxides (1) and the Ta2O5-Ta2WO8 system (2).According to the X-ray data both structures have orthorhombic unit cells with a = 6.2, b = 29.3, c = 3.9Å. The structures are based on the U03-type and the b spacings are nearly 8 times those of the subcell. Electron diffraction (E.D.) patterns of L-Nb2O5 and L-Ta3O5 crystals showing a*-b* reciprocal sections confirmed generally the results of X-ray works (Figs, la and lc).

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Slow-Scan CCD Observation of Backscattering Patterns in SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1308-1309
Author(s):  
F. Ouyang ◽  
D. A. Ray ◽  
O. L. Krivanek
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Dynamic Range ◽  
High Sensitivity ◽  
Lens System ◽  
Wide Dynamic Range ◽  
Peltier Cooler ◽  
Diffraction Patterns ◽  
Scanning Electron

Electron backscattering Kikuchi diffraction patterns (BKDP) reveal useful information about the structure and orientation of crystals under study. With the well focused electron beam in a scanning electron microscope (SEM), one can use BKDP as a microanalysis tool. BKDPs have been recorded in SEMs using a phosphor screen coupled to an intensified TV camera through a lens system, and by photographic negatives. With the development of fiber-optically coupled slow scan CCD (SSC) cameras for electron beam imaging, one can take advantage of their high sensitivity and wide dynamic range for observing BKDP in SEM.We have used the Gatan 690 SSC camera to observe backscattering patterns in a JEOL JSM-840A SEM. The CCD sensor has an active area of 13.25 mm × 8.83 mm and 576 × 384 pixels. The camera head, which consists of a single crystal YAG scintillator fiber optically coupled to the CCD chip, is located inside the SEM specimen chamber. The whole camera head is cooled to about -30°C by a Peltier cooler, which permits long integration times (up to 100 seconds).

Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

1994 ◽  
Vol 52 ◽  
pp. 412-413
Author(s):  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Damage ◽  
Low Dose ◽  
Dynamic Range ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Digital Data ◽  
Ccd Cameras ◽  
Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

Electron Microscope Image Contrast for Thin Crystal

1972 ◽  
Vol 27 (3) ◽  
pp. 445-451 ◽  
Author(s):  
J. M. Cowley ◽  
Sumio Iijima
Keyword(s):  
Electron Microscope ◽  
Phase Contrast ◽  
Complex Oxide ◽  
Phase Shifts ◽  
Image Contrast ◽  
Crystal Thickness ◽  
Contrast Imaging ◽  
Resolution Electron ◽  
Unit Cells ◽  
Correct Account

AbstractHigh resolution electron microscope images showing the detailed distribution of metal atoms within the unit cells of complex oxide structures have been recorded recently and as a first approximation may be interpreted as amplitude-object images if obtained with the degree of defocus corresponding to the "optimum-defocus condition" for the phase-contrast imaging of thin phase objects. Detailed observations of images of Ti2Nb10O29 crystals having thicknesses of the order of 100 Å reveal that the thin phase-object approximation, which assumes that only small phase-shifts are involved, is inadequate to explain some features of the image intensities including the variation of contrast with crystal thickness. A very aproximate treatment of the phase contrast due to defocussing of phase objects having large phase shifts is evolved and shown to give a qualitativity correct account of the observations. The variation of image contrast with tilt away from a principle orientation is discussed. From the symmetry of the image contrast it is deduced that the symmetry of the crystal structure as derived from X-ray diffraction studies can not be correct.

scholarly journals On the Formation of AlNiCo Nano-Quasicrystalline Phase during Mechanical Alloying through Electroless Ni-P Plating of Starting Particles

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2294 ◽  
Author(s):  
Seyedmehdi Hosseini ◽  
Pavel Novák
Keyword(s):  
Electron Microscope ◽  
Mechanical Alloying ◽  
Protective Atmosphere ◽  
Quasicrystalline Phase ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Transmission Electron ◽  
New Strategy ◽  
Diffraction Patterns ◽  
Electroless Ni

A new strategy was applied to develop nano-quasicrystalline phase in well-known AlNiCo ternary system. This approach was based on electroless Ni-P plating of the starting powders and subsequent ball milling in a protective atmosphere without additional annealing or sintering processes. Microstructural evolution and phase transformation of both raw and coated particles were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. After 360 min of mechanical alloying, the peaks demonstrating the formation of nano-quasicrystalline phase appeared in XRD pattern of the coated powders, while those in mechanically alloyed raw powders remained mostly unchanged. The formation of nano-quasicrystalline phase in the vicinity of the primary elements was also confirmed by the corresponding selected area diffraction patterns, and images generated by transmission electron microscope (TEM).

Direct Observation of the Surface Topography of Single Crystals in a Transmission Electron Microscope

1981 ◽  
Vol 39 ◽  
pp. 208-211
Author(s):  
G. Lehmpfuhl ◽  
Y. Uchida
Keyword(s):  
Electron Microscope ◽  
Electron Diffraction ◽  
Surface Topography ◽  
Single Crystals ◽  
Dynamic Effect ◽  
Thickness Variation ◽  
Crystal Thickness ◽  
Kinematic Effect ◽  
Diffraction Patterns ◽  
Small Change

From the analysis of convergent-beam electron diffraction patterns it is well known that the intensity of some reflections may become most sensitive to the crystal thickness variation at special conditions for thickness and orientation. This can be understood as a dynamic effect as well as a kinematic effect of electron diffraction. Using such a diffracted beam for imaging, a small change in thickness of a single crystal can be observed in an electron microscope. At the beginning of the application of this technique only weak beams were used for imaging the surface topography of undistorted single crystals. Thickness differences down to the atomic level could be detected in darkfield micrographs of MgO and Au. However, the intensity of the weak beams was so low that long exposure times up to 2 minutes were necessary to record a micrograph at a magnification of 20,000. This magnification is the upper limit for the weak-beam darkfield technique for reasons of stability of the electron microscope. The thickness contrast can be explained already by the kinematical theory of electron diffraction.

Extension of the “thin-crystal” condition by small crystal tilts: Why HREM images of SiC polytypes always look tilted

1992 ◽  
Vol 50 (1) ◽  
pp. 116-117
Author(s):  
Michael A. O'Keefe ◽  
Velimir Radmilovic
Keyword(s):  
Silicon Carbide ◽  
Electron Microscope ◽  
High Resolution ◽  
Group Symmetry ◽  
Crystal Thickness ◽  
Resolution Electron ◽  
Microscope Images ◽  
High Resolution Electron Microscope ◽  
Simulated Images ◽  
Thin Crystal

Both experimental and simulated high-resolution electron microscope images of silicon carbide polytypes commonly exhibit symmetry changes in thicker crystal regions compared to the perfect (projected) space group symmetry of images from thin crystals. However, the changes predicted by simulation, and those found experimentally, are quite different.High-resolution transmission electron microscope images of silicon carbide polytypes were obtained with the JEOL ARM-1000 high-resolution electron microscope in the course of an investigation into a series of metal matrix composites. Like all HRTEM images of silicon carbide, these images failed to show the correct symmetry in the thicker parts of the specimen. Changes in image symmetry as crystal thickness is increased also occur when images of silicon carbide are simulated; for example, Smith and O'Keefe simulated images of polytypes of silicon carbide for crystals oriented so that the electron beam was precisely along the <1210> direction, and found marked departure from thin-crystal symmetry at thicknesses of the order of 150Å for an electron energy of 500keV. However, the lack of symmetry in their simulated images appears to be due to the presence of many second-order terms contributing to the intensity spectra of the thick-crystal images, whereas the symmetry changes in experimental images from thicker crystals are usually of the form that preserves the thin-crystal-like contrast for one set of “twin” spots, yet smears out the contrast of the other. A typical example of this latter effect can be seen in the image of the 6H variant of SiC shown in figure 1.

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