A Method For The Tem Characterisation Of Grain Boundary Films In Ceramics

1981 ◽  
Vol 5 ◽  
Author(s):  
N.W. Jepps ◽  
T. F. Page ◽  
W. M. Stobbs
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Dark Field ◽  
Engineering Ceramics ◽  
Dark Field Imaging ◽  
Silicon Carbides ◽  
Boundary Films ◽  
Field Imaging ◽  
Complete Characterisation

ABSTRACTThe behaviour of Fresnel fringes with focus has been investigated as a means of characterising grain boundaries in engineering ceramics. This technique, together with dark-field imaging, has been applied to the study of grain boundaries in two hot-pressed silicon carbides. It is demonstrated that these two techniques, applied together, provide the best means of obtaining a complete characterisation of grain boundary films, in terms of width, structure, and composition.

Grain Boundary Segregation in NI-Base Alloys: an Integrated Approach using FIB, TEM and SIMS

2001 ◽  
Vol 7 (S2) ◽  
pp. 930-931
Author(s):  
G. McMahon ◽  
M. Phaneuf
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Microstructural Analysis ◽  
Boundary Segregation ◽  
Integrated Approach ◽  
Dark Field ◽  
Grain Boundary Segregation ◽  
Corrosion Properties ◽  
Auger Analysis ◽  
Dark Field Imaging

Segregation of elements to the grain boundaries in Ni-base alloys can have a large effect on the mechanical and corrosion properties of these materials. The extent of segregation, whether it is equilibrium or non-equilibrium segregation, is dependent upon the thermo-mechanical treatments applied to the alloy. in order to determine if a particular thermo-mechanical process delivers the desired microstructure, a complete microstructural analysis including an examination of grain boundary segregation must be performed.In the past, TEM has been used to identify the various phases and precipitates in these materials through the use of bright- and dark-field imaging, electron diffraction, and EDS. However, one of the elements that can play a large role in determining the properties of these alloys is boron. in this group of alloys, boron is generally present in bulk analyses in only a few tens of ppm, and as a result it is difficult to detect using the aforementioned techniques. More commonly, boron segregation to the grain boundaries is usually studied by means of Auger analysis, whereby the sample is charged with hydrogen in order to promote brittle intergranular fracture in-situ in the Auger microprobe. Boron can then be detected at the surface of the clean grain boundary fracture surfaces.

scholarly journals Grain Size Determination and Grain Boundary Characterization of Nanocrystalline Thin Films from Conical Dark Field Imaging

2010 ◽  
Vol 16 (S2) ◽  
pp. 1276-1277
Author(s):  
A Darbal ◽  
K Barmak ◽  
T Nuhfer ◽  
T Sun ◽  
KR Coffey
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Grain Boundary ◽  
Dark Field ◽  
Size Determination ◽  
Dark Field Imaging ◽  
Field Imaging ◽  
Nanocrystalline Thin Films

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Detection of a point defect in a silicon single crystal by high-resolution TEM

1995 ◽  
Vol 53 ◽  
pp. 466-467
Author(s):  
M. Awaji
Keyword(s):  
High Resolution ◽  
Single Crystal ◽  
Point Defect ◽  
Point Defects ◽  
Noise Level ◽  
Dark Field ◽  
Silicon Single Crystal ◽  
High Resolution Image ◽  
Dark Field Imaging ◽  
Field Imaging

It is necessary to improve the resolution, brightness and signal-to-noise ratio(s/n) for the detection and identification of point defects in crystals. In order to observe point defects, multi-beam dark-field imaging is one of the useful methods. Though this method can improve resolution and brightness compared with dark-field imaging by diffuse scattering, the problem of s/n still exists. In order to improve the exposure time due to the low intensity of the dark-field image and the low resolution, we discuss in this paper the bright-field high-resolution image and the corresponding subtracted image with reference to a changing noise level, and examine the possibility for in-situ observation, identification and detection of the movement of a point defect produced in the early stage of damage process by high energy electron bombardment.The high-resolution image contrast of a silicon single crystal in the [10] orientation containing a triple divacancy cluster is calculated using the Cowley-Moodie dynamical theory and for a changing gaussian noise level. This divacancy model was deduced from experimental results obtained by electron spin resonance. The calculation condition was for the lMeV Berkeley ARM operated at 800KeV.

scholarly journals Noninvasive, in vivo assessment of the cervical microcirculation using incident dark field imaging

2021 ◽  
Vol 135 ◽  
pp. 104145
Author(s):  
Yani P. Latul ◽  
Arnoud W. Kastelein ◽  
Patricia W.T. Beemster ◽  
Nienke E. van Trommel ◽  
Can Ince ◽  
...  
Keyword(s):  
Dark Field ◽  
Dark Field Imaging ◽  
Incident Dark Field Imaging ◽  
Field Imaging ◽  
In Vivo Assessment

scholarly journals Correlation of image quality parameters with tube voltage in X-ray dark-field chest radiography: a phantom study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andreas P. Sauter ◽  
Jana Andrejewski ◽  
Manuela Frank ◽  
Konstantin Willer ◽  
Julia Herzen ◽  
...  
Keyword(s):  
Image Quality ◽  
Imaging Modality ◽  
Signal Strength ◽  
Dark Field ◽  
Tube Voltage ◽  
X Ray ◽  
Dose Area Product ◽  
Dark Field Imaging ◽  
Field Imaging

AbstractGrating-based X-ray dark-field imaging is a novel imaging modality with enormous technical progress during the last years. It enables the detection of microstructure impairment as in the healthy lung a strong dark-field signal is present due to the high number of air-tissue interfaces. Using the experience from setups for animal imaging, first studies with a human cadaver could be performed recently. Subsequently, the first dark-field scanner for in-vivo chest imaging of humans was developed. In the current study, the optimal tube voltage for dark-field radiography of the thorax in this setup was examined using an anthropomorphic chest phantom. Tube voltages of 50–125 kVp were used while maintaining a constant dose-area-product. The resulting dark-field and attenuation radiographs were evaluated in a reader study as well as objectively in terms of contrast-to-noise ratio and signal strength. We found that the optimum tube voltage for dark-field imaging is 70 kVp as here the most favorable combination of image quality, signal strength, and sharpness is present. At this voltage, a high image quality was perceived in the reader study also for attenuation radiographs, which should be sufficient for routine imaging. The results of this study are fundamental for upcoming patient studies with living humans.

3d Reconstruction of Sub-Nm Beam Profiles in STEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 344-345
Author(s):  
G. Möbus ◽  
R.E. Dunin-Borkowski ◽  
C.J.D. Hethėrington ◽  
J.L. Hutchison
Keyword(s):  
Electron Beam ◽  
Chemical Analysis ◽  
Energy Loss ◽  
Intensity Distribution ◽  
Dark Field ◽  
Beam Forming ◽  
Dark Field Imaging ◽  
Annular Dark Field ◽  
Electron Energy Loss ◽  
Field Imaging

Introduction:Atomically resolved chemical analysis using techniques such as electron energy loss spectroscopy and annular dark field imaging relies on the ability to form a well-characterised sub-nm electron beam in a FEGTEM/STEM [1-2]. to understand EELS+EDX-signal formation upon propagation of a sub-nm beam through materials we first have to assess precisely the beam intensity distribution in vacuum and find conditions for the best obtainable resolution.Experimental Details:Modern TEM/STEM instruments combine features of both imaging and scanning technology. The beam forming capability approaches closely that for dedicated STEMs, while CCD recording devices allow us to measure the beam profile by direct imaging at magnifications up to 1.5 M. The recording of a “z-section” series through the 3D intensity distribution of the cross-over can therefore be realised by recording of a “condenser focal series”.

Phase and dark‐field imaging with mesh‐based structured illumination and polycapillary optics

2021 ◽  
Author(s):  
Uttam Pyakurel ◽  
Weiyuan Sun ◽  
Pikting Cheung ◽  
Desirée D'Moore ◽  
Xiaoyun Zhang ◽  
...  
Keyword(s):  
Dark Field ◽  
Structured Illumination ◽  
Polycapillary Optics ◽  
Dark Field Imaging ◽  
Field Imaging
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