Quantifying The Effects Of Amorphous Layers on Image Contrast Using Energy Filtered Transmission Electron Microscopy

1994 ◽  
Vol 354 ◽  
Author(s):  
C. B. Boothroyd ◽  
R. E. Dunin-borkowski ◽  
W. M. Stobbs ◽  
C. J. Humphreys

AbstractHigh resolution images of a block oxide, (Nb205)çi(W03)8, with and without a superposed carbon film are compared both energy filtered and including the inelastic scattering. The differences between the images are quantified on an absolute intensity scale and possible origins of the differences in atomic level contrast are assessed using multislice simulations.

2011 ◽  
Vol 18 (1) ◽  
pp. 212-217 ◽  
Author(s):  
Björn Gamm ◽  
Holger Blank ◽  
Radian Popescu ◽  
Reinhard Schneider ◽  
André Beyer ◽  
...  

AbstractSingle atoms can be considered as the most basic objects for electron microscopy to test the microscope performance and basic concepts for modeling image contrast. In this work high-resolution transmission electron microscopy was applied to image single platinum, molybdenum, and titanium atoms in an aberration-corrected transmission electron microscope. The atoms are deposited on a self-assembled monolayer substrate that induces only negligible contrast. Single-atom contrast simulations were performed on the basis of Weickenmeier-Kohl and Doyle-Turner form factors. Experimental and simulated image intensities are in quantitative agreement on an absolute intensity scale, which is provided by the vacuum image intensity. This demonstrates that direct testing of basic properties such as form factors becomes feasible.


2012 ◽  
Vol 590 ◽  
pp. 9-12 ◽  
Author(s):  
Tamara Mekhantseva ◽  
Oleg Voitenko ◽  
Ilya Smirnov ◽  
Evgeny Pustovalov ◽  
Vladimir Plotnikov ◽  
...  

This paper covers the analysis of amorphous alloys CoP-CoNiP system by means of high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy and electron tomography. The last years have seen a sufficient progress in the analysis of nanomaterials structure with the help of high resolution tomography. This progress was motivated by the development of microscopes equipped with aberration correctors and specialized sample holders which allow reaching the tilts angles up to ±80°. The opportunities delivered by the method of electron tomography sufficiently grow when producing high resolution images and using chemical analysis, such as X-Ray energy-dispersive microanalysis and electron energy loss spectroscopy (EELS).


Author(s):  
M.J. Mills

The fine structure of dislocations plays a critical role in determining the macroscopic mechanical behavior Intermetallic compounds. Many of the technologically important characteristics of these compounds, an example their strength at high temperatures, appear to be determined by intricate details of dislocation stucture at the atomic level. High resolution transmission electron microscopy (HREM) offers the etential to obtain structural information at this level by observing these line defects in an "end-on" configuration.Samples of HREM images of several important dislocation types in Ni3Al and TiAl are shown in Figures through 3. Each of these particular dislocation types (i.e. Burgers vectors and line directions) tend to be longly favored in these compounds, indicating that along these line directions the dislocations are likely have either low mobility or low energy.


1983 ◽  
Vol 31 ◽  
Author(s):  
K. J. Morrissey ◽  
Z. Elgat ◽  
Y. Kouh ◽  
C. B. Carter

ABSTRACTHigh resolution transmission electron microscopy (HRTEM) has been used to study structures found in secondphase particles in commercial alumina compacts. Analytical electron microscopy has been used to identify elements present in the particles. Computer image simulation has been used for both the structural interpretation of high resolution images and predicting the effect which the presence of other elements would have on the observed structures.


Author(s):  
K. Fortunati ◽  
M. Fendorf ◽  
M. Powers ◽  
C.P. Burmester ◽  
R. Gronsky

Transmission electron microscopy, in particular high-resolution TEM, is proving to be a valuable tool in the continuing effort to characterize and understand the “high-Tc” superconducting oxides. Since specimen quality is of critical importance in high-resolution studies, care must be taken to choose the most appropriate specimen preparation technique for the material under study. The BiCaSrCuO material investigated here was in the form of small, sintered pellets with a porous microstructure which consists of small, randomly oriented, poorly connected, plate-like grains (see Figure 1). We have found that this morphology can significantly effect the production of suitable TEM specimens.The simplest and most rapid specimen preparation method employed consists of crushing a small amount of the starting material to a fine powder in an agate mortar and suspending the powder in pure ethanol or propanol. An eye dropper or syringe is then used to transfer 4-6 drops of the suspension onto a holey carbon film supported on a mesh grid, thus effectively dispersing the powder across the grid. A strong tendency for the crystal to cleave along (001) planes, due to the weak bonding between BiO layers, results in flake-like particles which exhibit a preferred [001] orientation on the grid. A high-resolution image of a specimen prepared using this method is shown in Figure 2. We have observed that some specimens produced in this manner are unstable under a 200kV beam (with LaB6 filament), with heavy damage occurring within the time that a through-focus series of micrographs can be exposed. It is also important to note that since separation along grain boundaries occurs during crushing, this method is not an appropriate choice for imaging grain boundary structures.


Author(s):  
M. M. Tsai ◽  
J. M. Howe

Precipitation of γ-TiH in α-Ti-H alloys involves a hcp → fct lattice transformation with hydrogen as an interstitial diffusing element Results obtained from a previous TEM study have shown that the lengthening rate of γ-TiH is diffusionally controlled at 25°C, and possibly interfacially controlled at temperatures of 50°C and higher. Therefore, it is essential to ascertain the presence or absence of hydrogen atoms at the interface. TEM foils from a 800 ppm wt.% Ti-H alloy were analyzed using high-resolution TEM and image simulations in order to determine the effects of hydrogen on high-resolution images of the α-Ti/γ-TiH interface, and EELS was used to determine the whether the hydnde structure was fully formed up to the interface.


MRS Bulletin ◽  
2008 ◽  
Vol 33 (2) ◽  
pp. 115-121 ◽  
Author(s):  
James M. Howe ◽  
Hirotaro Mori ◽  
Zhong Lin Wang

AbstractThis article introduces the use of in situ high-resolution transmission electron microscopy (HRTEM) techniques for the study and development of nanomaterials and their properties. Specifically, it shows how in situ HRTEM (and TEM) can be used to understand diverse phenomena at the nanoscale, such as the behavior of alloy phase formation in isolated nanometer-sized particles, the mechanical and transport properties of carbon nanotubes and nanowires, and the dynamic behavior of interphase boundaries at the atomic level. Current limitations and future potential advances in in situ HRTEM of nanomaterials are also discussed.


Author(s):  
R. Gronsky

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.


Author(s):  
Chung-Ching Lin ◽  
Franco Stellari ◽  
Lynne Gignac ◽  
Peilin Song ◽  
John Bruley

Abstract Transmission Electron Microscopy (TEM) and scanning TEM (STEM) is widely used to acquire ultra high resolution images in different research areas. For some applications, a single TEM/STEM image does not provide enough information for analysis. One example in VLSI circuit failure analysis is the tracking of long interconnection. The capability of creating a large map of high resolution images may enable significant progress in some tasks. However, stitching TEM/STEM images in semiconductor applications is difficult and existing tools are unable to provide usable stitching results for analysis. In this paper, a novel fully automated method for stitching TEM/STEM image mosaics is proposed. The proposed method allows one to reach a global optimal configuration of each image tile so that both missing and false-positive correspondences can be tolerated. The experiment results presented in this paper show that the proposed method is robust and performs well in very challenging situations.


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