Quantitative determination of defocus, thickness and composition from high-resolution transmission electron microscopy lattice images

1996 ◽  
Vol 62 (4) ◽  
pp. 369-372 ◽  
Author(s):  
D. Stenkamp ◽  
H. P. Strunk
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Quantitative Determination ◽  
Transmission Electron ◽  
Lattice Images

Quantitative determination of imaging parameters and composition from high-resolution transmission electron microscopy lattice images

1996 ◽  
Vol 54 ◽  
pp. 96-97
Author(s):  
D. Stenkamp
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Sample Thickness ◽  
Inelastic Electron ◽  
Local Composition ◽  
Transmission Electron ◽  
Non Linear ◽  
Lattice Images

A quantitative method for the direct determination of defocus Δf, local sample thickness t and local composition x from high-resolution transmission electron microscopy (HRTEM) lattice images of wedge-shaped samples is described. The method is applicable to a wide class of crystalline materials comprising elemental semiconductors, elemental metals and substitutional random alloys composed of these elements. The proposed method relies on the functional dependence of linear and non-linear image Fourier coefficients on the parameters defocus Δf, sample thickness t and composition x. This relationship is analytically derived by application of the Bloch wave formalism and the non-linear imaging theory to the HRTEM imaging process. Influences of inelastic electron scattering and partially coherent illumination conditions are taken into account explicitly.

Structural study of Cd(S,Se) doped glasses. High-resolution transmission electron microscopy (HRTEM) assisted by image processing

1990 ◽  
Vol 23 (5) ◽  
pp. 418-423 ◽  
Author(s):  
M. Allais ◽  
M. Gandais
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Bulk Material ◽  
Optical Filters ◽  
Characteristic Size ◽  
Transmission Electron ◽  
Doped Glasses ◽  
Lattice Images ◽  
Average Size

High-resolution transmission electron microscopy (HRTEM) was used for examining Cd(S,Se) nanocrystals grown in silicate glasses commercially available as optical filters. The lattice images of the nanocrystals were numerated and submitted to filtering through Fourier transformation in order to sweep off the background signal originating mainly from glass. Optical filters from several firms were examined. The nanocrystals have been identified with Cd(S,Se) compounds crystallized in the wurzite structure, as in bulk material. The lattice images indicate crystallites having the shape of hexagonal prisms a little elongated along the c axis. The distribution of grain size differs according to the filter: the smallest size being about 1.5 nm (threshold for detection), the largest size varies from 7 to 10 nm, the average size sa , from 3–4 to 5–6 nm and the characteristic size sc from 5–6 to 7–8 nm (sc is the size of grains occupying the main part of the crystallized volume).

Preparation of vermiculites for HRTEM

Clay Minerals ◽  
1989 ◽  
Vol 24 (1) ◽  
pp. 23-32 ◽  
Author(s):  
CH. Marcks ◽  
H. Wachsmuth ◽  
H. Graf V. Reichenbach
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Computer Simulation ◽  
High Resolution ◽  
Alkyl Chains ◽  
Transmission Electron ◽  
Lattice Images ◽  
Silicate Layers

AbstractA technique for preparing vermiculites for examination by high-resolution transmission electron microscopy (HRTEM) has been developed. A TEM-stable expanded phase can be obtained by intercalating n-alkylammonium ions between the silicate layers of a parent biotite. The vermiculite particles were embedded in Spurr resin and centrifuged to improve orientation. Ultra-thin specimens were prepared using an ultramicrotome, the quality and thickness of the sections being monitored by TEM. Lattice images of biotite, Ba-vermiculite and octylammonium-vermiculite, the latter showing a perpendicular arrangement of the alkyl chains relative to the silicate layers, were obtained with a resolution ∼2 Å. The reliability of these images was confirmed by computer simulation.

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