What Are Present Limits of Quantitative High Resolution Tem?

1997 ◽  
Vol 3 (S2) ◽  
pp. 935-936
Author(s):  
Christian Kisielowski
Keyword(s):  
Pattern Recognition ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Chemical Imaging ◽  
Atomic Scale ◽  
Lattice Image ◽  
Recognition Procedure ◽  
Unit Cells ◽  
High Resolution Tem ◽  
Lattice Images

In recent years quantitative high resolution electron microscopy (HREM) became a reliable tool to investigate physical processes at an atomic scale. Certainly, there is no unique approach to quantify the information content from lattice images. However, specific methods like Chemical Imaging^ and QUANTITEM were established that allow to investigate the atomic structure of crystalline solids quantitatively and almost routinely.Nevertheless, there are limits to the application of these methods and they are of principle and of practical nature. Obviously, the resolution of quantitative HRTEM is limited by the point resolution of modern microscopes that has reached 0.1 mn. However, the quantification of the information from lattice images requires two important steps, namely, the application of a pattern recognition procedure and the extraction of changes of the electron scattering potential from the lattice images. The application of the pattern recognition procedure influences the lateral resolution of the method because a lattice image has to be broken up into unit cells of identical size (figure 1).

The ultrastructure of coccoliths from the marine alga Emiliania huxleyi (Lohmann) Hay and Mohler: an ultra-high resolution electron microscope study

1983 ◽  
Vol 219 (1215) ◽  
pp. 111-117 ◽  
Keyword(s):  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Emiliania Huxleyi ◽  
Growth Patterns ◽  
Lattice Image ◽  
Nucleation Sites ◽  
Resolution Electron ◽  
Lattice Images ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns

The calcite coccoliths from the alga Emiliania huxleyi (Lohmann) Hay and Mohler have been studied by ultra-high resolution electron microscopy. This paper describes the two different types of structure observed, one in the upper elements, the other in the basal plate, or lower element. The former consisted of small, microdomain structures of 300-500 Å (1 Å = 10 -10 m) in length with no strong orientation. At places along these elements, and particularly in the junction between stem and head pieces, triangular patterns of lattice fringes were observed indicating multiple nucleation sites in the structure. In contrast, the lower element consisted of a very thin single crystalline sheet of calcite which could be resolved into a two dimensional lattice image, shown by a computer program that is capable of simulating electron diffraction patterns and lattice images to be a [421] zone of calcite. A possible mechanism for these growth patterns in the formation of coccoliths is discussed, together with the relevance of such mechanisms to biomineralization generally.

Pattern Recognition in High-Resolution Electron Microscopy of Complex Materials

2006 ◽  
Vol 12 (6) ◽  
pp. 476-482 ◽  
Author(s):  
Tore Niermann ◽  
Karsten Thiel ◽  
Michael Seibt
Keyword(s):  
Pattern Recognition ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Structural Features ◽  
Complex Materials ◽  
Amorphous Phases ◽  
Resolution Electron ◽  
Unit Cells ◽  
Local Patterns ◽  
Magneto Resistance

Structural features like defects or heterointerfaces in crystals or amorphous phases give rise to different local patterns in high-resolution electron micrographs or object wave functions. Pattern recognition techniques can be used to identify these typical patterns that constitute the image itself, as was already demonstrated for compositional changes in isostructural heterostructures, where the patterns within unit cells of the lattice were analyzed. To extend such analyses to more complex materials, we examined patterns in small circular areas centered on intensity maxima of the image. Nonsupervised clustering, namely, Ward's clustering method, was applied to these patterns. In two examples, a highly defective ZnMnTe layer on GaAs and a tunnel magneto resistance device, we demonstrate how typical patterns are identified by this method and how these results can be used for a further investigation of the microstructural properties of the sample.

X-Ray-Optical Multilayer Structures Studied Using High Resolution Electron Microscopy.

1986 ◽  
Vol 77 ◽  
Author(s):  
Mary Beth Stearns ◽  
Amanda K. Petford-Long ◽  
C.-H. Chang ◽  
D. G. Stearns ◽  
N. M. Ceglio ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Substrate Surface ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Degree Of Crystallinity ◽  
Multilayer Systems ◽  
Layer Width ◽  
X Ray ◽  
Resolution Electron

ABSTRACTThe technique of high resolution electron microscopy has been used to examine the structure of several multilayer systems (MLS) on an atomic scale. Mo/Si multilayers, in use in a number of x-ray optical element applications, and Mo/Si multilayers, of interest because of their magnetic properties, have been imaged in cross-section. Layer thicknesses, flatness and smoothness have been analysed: the layer width can vary by up to 0.6nm from the average value, and the layer flatness depends on the quality of the substrate surface for amorphous MLS, and on the details of the crystalline growth for the crystalline materials. The degree of crystallinity and the crystal orientation within the layers have also been investigated. In both cases, the high-Z layers are predominantly crystalline and the Si layers appear amorphous. Amorphous interfacial regions are visible between the Mo and Si layers, and crystalline cobalt suicide interfacial regions between the Co and Si layers. Using the structural measurements obtained from the HREM results, theoretical x-ray reflectivity behaviour has been calculated. It fits the experimental data very well.

scholarly journals HRTEM image-stitching for measurement of distances

2020 ◽  
Vol 5 (1) ◽  
pp. 13-17
Author(s):  
György Zoltán Radnóczi ◽  
Zoltán Herceg ◽  
Tamás Rafael Kiss
Keyword(s):  
Electron Beam ◽  
High Resolution ◽  
Single Crystal ◽  
Image Stitching ◽  
Hrtem Image ◽  
Lattice Image ◽  
High Resolution Tem ◽  
Better Than

AbstractVery accurate measurement of distances in the order of several µm is demonstrated on a single crystal Si sample by counting the lattice fringes on stitched high resolution TEM/STEM images. Stitching of TEM images commonly relies on correspondence points found in the image, however, the nearly perfect periodic nature of a lattice image renders such a procedure very unreliable. To overcome this difficulty artificial correspondence points are created on the sample using the electron beam. An accuracy better than 1% can be reached while measuring distances in the order of 1 µm. A detailed description of the process is provided, and its usability for accurately measuring large distances is discussed in detail.

High-resolution electron microscopy of epitaxial YBCO/Y2O3/YSZ on Si(001)

1993 ◽  
Vol 8 (9) ◽  
pp. 2112-2127 ◽  
Author(s):  
A. Bardal ◽  
O. Eibl ◽  
Th. Matthée ◽  
G. Friedl ◽  
J. Wecker
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Thick Layer ◽  
Atomic Layer ◽  
High Resolution Electron Microscopy ◽  
Stacking Fault ◽  
Buffer Layers ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
Unit Cells

The microstructures of YBa2Cu3O7−δ (YBCO) thin films grown on Si with Y-stabilized ZrO2 (YSZ) and Y2O3 buffer layers were characterized by means of high-resolution electron microscopy. At the Si–YSZ interface, a 2.5 nm thick layer of regrown amorphous SiOx is present. The layer is interrupted by crystalline regions, typically 5 to 10 nm wide and 10 to 50 nm apart. Close to the crystalline regions, {111} defects are present in the Si substrate. The typical defect observed is an extrinsic stacking fault plus a perfect dislocation close to the stacking fault which terminates extra {111} planes in the upper part of the Si. These defects are probably formed by condensation of Si self-interstitials created during oxide regrowth. Precipitates are present in the Si close to the Si–YSZ interface and indicate that in-diffusion of Zr has occurred. The YSZ–Y2O3 interface is atomically sharp and essentially planar and contains no second phases. Perfect misfit dislocations with Burgers vector 1/2〈110〉 are present at this interface along with unrelaxed elastic misfit stresses. The Y2O3–YBCO interface is atomically sharp and planar, but contains steps. (001) stacking faults are present in the YBCO above these steps; the faults are, however, healed a few unit cells away from the interface. By HREM analysis of ultrathin specimen areas, the atomic layer of the YBCO closest to the Y2O3 was found to be a barium-oxygen layer.

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.

Interfacial Atomic Structures During Cobalt Silicidation

1990 ◽  
Vol 202 ◽  
Author(s):  
A. Catana ◽  
P.E. Schmid
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Type B ◽  
Cross Sectional ◽  
Atomic Structures ◽  
Resolution Electron ◽  
Predominant Orientation ◽  
Lower Temperature

ABSTRACTHigh Resolution Electron Microscopy (HREM) and image calculations are combined to study microstructural changes related to the CoSi/Si-CoSi/CoSi2/Si-CoSi2/Si transformations. The samples are prepared by UHV e-beam evaporation of Co layers (2 nm) followed by annealing at 300°C or 400°C. Cross-sectional observations at an atomic scale show that the silicidation of Co at the lower temperature yields epitaxial CoSi/Si domains such that [111]Si // [111]CoSi and <110>Si // <112>CoSi. At about 400°C CoSi2 nucleates at the CoSi/Si interface. During the early stages of this chemical reaction, an epitaxial CoSi/CoSi2/Si system is observed. The predominant orientation is such that (021) CoSi planes are parallel to (220) CoSi2 planes, the CoSi2/Si interface being of type B. The growth of CoSi2 is shown to proceed at the expense of both CoSi and Si.

High Resolution TEM Studies On Palladium, Rhodium Nanoparticles

2001 ◽  
Vol 7 (S2) ◽  
pp. 1100-1101
Author(s):  
M. José-Yacamán ◽  
M. Marín-Almazo ◽  
J.A. Ascencio
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Indirect Evidence ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Rhodium Nanoparticles ◽  
Resolution Electron ◽  
Annular Dark Field ◽  
High Resolution Tem ◽  
Important Field

The field of catalysis is one of the most important areas of the nano-sciences for many years. in deed the goal of having a catalyst, with the maximum active area exposed to a chemical reaction, has produced enormous amount of research in nanoparticles. Particularly, the metal nanoparticles study is a very important field in catalysis. Electron Microscopy is one of the techniques that have played a mayor role on studding nanoparticles. Since bright field images, dark field techniques, to the high-resolution atomic images of nanoparticles and more recently the High Angle Annular dark field images or Z-contrast. However this technique provides only indirect evidence of the atomic arrangements on the particles. High Resolution Electron Microscopy (HREM) still appears as a very powerful technique to study nanoparticles and their internal structure. Among the most interesting metals to study is the palladium, which acts for instance as excellent catalyst for hydrogenation of unsaturated hydrocarbons and has many other applications such as environmental catalysts.

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