Extraction of structural and chemical information from high angle annular dark-field image by an improved peaks finding method

2016 ◽  
Vol 79 (9) ◽  
pp. 820-826 ◽  
Author(s):  
Wenhao Yin ◽  
Rong Huang ◽  
Ruijuan Qi ◽  
Chungang Duan
Keyword(s):  
Dark Field Image ◽  
Dark Field ◽  
Chemical Information ◽  
High Angle ◽  
Annular Dark Field ◽  
Finding Method

Stem Dark-Field Image Using A 200-kV AEM

1996 ◽  
Vol 54 ◽  
pp. 444-445
Author(s):  
T. Tomita ◽  
T. Honda ◽  
M. Kersker
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Thermal Field ◽  
Imaging System ◽  
Dark Field Image ◽  
Dark Field ◽  
Specimen Thickness ◽  
High Angle ◽  
Long Term Stability ◽  
Annular Dark Field

Interpretation of the high resolution transmission image typically requires simulation since the contrast changes in a complicated way due to changes in focus and specimen thickness. The contrast in images formed by collecting high angle forward scattered electrons in STEM does not change with changes in thickness or defocus.Until recently, high angle annular dark field (HADF) images were obtained only from instruments using cold field emission guns. Recently we have attempted to obtain HADF images using Schottky (ZrO/W(100)) thermal field emission and using a 200kV instrument designed as a comprehensive TEM/STEM. Advantages of the ZrO/W emitter are easy operation, very good short and long term stability, high brightness, and narrow energy spread. This microscope, The JEM2010F with thermal field emission, allows subnanometer analysis with EDS(spot, line, and mapping), EELS, holograms, etc, and has a standard TEM imaging system for high resolution imaging and for various diffraction modes, viz., CBED, selected area, Tanaka, etc.

scholarly journals The 1s-State Analysis Applied to High-Angle, Annular Dark-Field Image Interpretation—When Can We Use It?

2004 ◽  
Vol 10 (1) ◽  
pp. 4-8 ◽  
Author(s):  
Geoffrey R. Anstis
Keyword(s):  
Image Interpretation ◽  
Dark Field Image ◽  
Dark Field ◽  
High Angle ◽  
Atomic Column ◽  
Thermal Diffuse Scattering ◽  
Small Probe ◽  
Annular Dark Field ◽  
Electron Intensity ◽  
Thermal Diffuse

A small probe centered on an atomic column excites the bound and unbound states of the two-dimensional projected potential of the column. It has been argued that, even when several states are excited, only the 1sstate is sufficiently localized to contribute a signal to the high-angle detector. This article shows that non-1sstates do make a significant contribution for certain incident probe profiles. The contribution of the 1sstate to the thermal diffuse scattering is calculated directly. Sub-Ångstrom probes formed by Cs-corrected lenses excite predominantly the 1sstate and contributions from other states are not very large. For probes of lower resolution when non-1sstates are important, the integrated electron intensity at the column provides a better estimate of image intensity.

EM of rapidly solidified permanent magnets

1992 ◽  
Vol 50 (1) ◽  
pp. 198-199
Author(s):  
Raja K. Mishra
Keyword(s):  
Melt Spinning ◽  
Permanent Magnets ◽  
Dark Field Image ◽  
Dark Field ◽  
Maximum Energy ◽  
Quench Rate ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Annular Dark Field ◽  
Rapidly Solidified

The discovery of a new class of permanent magnets based on Nd2Fe14B phase in the last decade has led to intense research and development efforts aimed at commercial exploitation of the new alloy. The material can be prepared either by rapid solidification or by powder metallurgy techniques and the resulting microstructures are very different. This paper details the microstructure of Nd-Fe-B magnets produced by melt-spinning.In melt spinning, quench rate can be varied easily by changing the rate of rotation of the quench wheel. There is an optimum quench rate when the material shows maximum magnetic hardening. For faster or slower quench rates, both coercivity and maximum energy product of the material fall off. These results can be directly related to the changes in the microstructure of the melt-spun ribbon as a function of quench rate. Figure 1 shows the microstructure of (a) an overquenched and (b) an optimally quenched ribbon. In Fig. 1(a), the material is nearly amorphous, with small nuclei of Nd2Fe14B grains visible and in Fig. 1(b) the microstructure consists of equiaxed Nd2Fe14B grains surrounded by a thin noncrystalline Nd-rich phase. Fig. 1(c) shows an annular dark field image of the intergranular phase. Nd enrichment in this phase is shown in the EDX spectra in Fig. 2.

Influence of spatial and temporal coherences on atomic resolution high angle annular dark field imaging

2016 ◽  
Vol 169 ◽  
pp. 1-10 ◽  
Author(s):  
Andreas Beyer ◽  
Jürgen Belz ◽  
Nikolai Knaub ◽  
Kakhaber Jandieri ◽  
Kerstin Volz
Keyword(s):  
Dark Field ◽  
Atomic Resolution ◽  
High Angle ◽  
Dark Field Imaging ◽  
Annular Dark Field ◽  
Field Imaging

The Scattering Distribution from Semiconductors as a Function of Angle and Energy Loss in the Electron Microscope

1996 ◽  
Vol 466 ◽  
Author(s):  
C. B. Boothroyd ◽  
R. E. Dunin-Borkowski ◽  
T. Walther
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Dark Field ◽  
High Angle ◽  
Scattering Angle ◽  
Annular Dark Field ◽  
Insight Into

ABSTRACTWe examine the scattering distribution from thin C, Ge and thick Si specimens as a function of scattering angle and energy loss, in order to gain insight into the relative contributions to both low and high angle annular dark field images from elastically and inelastically scattered elections.

HREM and HAADF Studies of Precipitates in the Mg-Y-Nd Alloy System

2007 ◽  
Vol 561-565 ◽  
pp. 275-278
Author(s):  
Wei Sun ◽  
Li Sun ◽  
Lin Lin Liu ◽  
Ze Zhang
Keyword(s):  
Structural Model ◽  
Imaging Technique ◽  
Dark Field Image ◽  
Alloy System ◽  
Dark Field ◽  
Orthorhombic Unit Cell ◽  
Characteristic Distribution ◽  
Transmission Electron ◽  
Annular Dark Field ◽  
Image Technique

By means of high resolution transmission electron microscopy (HREM) and high-angle annular dark-field image technique (HAADF), morphological, structural and compositional characteristics of the precipitates in the Mg-4Y-3Nd alloy aged at 200°C for different periods of time have been studied. On the basis of HREM observations, an atomic structural model for the β’-precipitate with an orthorhombic unit cell has been proposed. The characteristic distribution of the precipitates which are rich in rare-earth elements (Y, Nd) has been clearly revealed by the HAADF imaging technique.

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