scholarly journals Determination of atomic positions and polar direction in half-Heusler material Sb1-xSnxTi1-y-zHfyZrzCo using electron channeling

AIP Advances ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 125335
Author(s):  
Vidar Hansen ◽  
Cristina Echevarria-Bonet ◽  
Mona Wetrhus Minde ◽  
Johan Taftø
Keyword(s):  
Electron Channeling ◽  
Polar Direction

Microcrack Nucleation and Crack Propagation in Equiaxed γ TiAl

2002 ◽  
Vol 753 ◽  
Author(s):  
Martin A. Crimp ◽  
Boon-Chi Ng ◽  
Benjamin A. Simkin ◽  
Thomas R. Bieler
Keyword(s):  
Ex Situ ◽  
Contrast Imaging ◽  
Active Deformation ◽  
Electron Channeling ◽  
Microcrack Initiation ◽  
Grain Orientations ◽  
Contrast Analysis ◽  
Defect Imaging

ABSTRACTTo gain a better understanding of the ductility limitations in TiAl alloys, the mechanisms involved in deformation strain transfer and/or microcrack initiation at grain boundaries have been examined in an equiaxed near-γ alloy. These studies have been carried out on both in-situ and ex-situ deformed bulk samples using scanning electron microscopy (SEM) techniques for both orientation analysis and deformation defect imaging. Selected area electron channeling patterns (SACPs) have allowed determination of grain orientations, eliminating ambiguity between the a and c axes. Deformation twins and dislocations have been imaged in the bulk samples using electron channeling contrast imaging (ECCI). A combination of ECCI contrast analysis and trace analysis based on orientations determined from SACP has allowed identification of the active deformation systems. Microcracks have been found to initiate at γ-γ boundaries as a result of an inability to adequately transfer twin strain from grain to grain. Once initiated, cracks propagate through cleavage and re-nucleation of grain boundary microcracks in front of the advancing crack. A geometric based predictive factor has been developed that accounts for microcrack initiation at γ-γ boundaries based in deformation twinning and strain accommodation by ordinary dislocations.

Crystal Polarity Determination by Electron Channeling

2001 ◽  
Vol 7 (S2) ◽  
pp. 334-335
Author(s):  
J. Tafto
Keyword(s):  
Experimental Conditions ◽  
Electron Channeling ◽  
Structure Factors ◽  
Small Crystals ◽  
Polarity Determination ◽  
Convergent Beam ◽  
Interface Structures ◽  
Diffraction Effects ◽  
Beam Diffraction

Multilayers, heterostructures, nanostructures and composites are of great interest to the materials scientists, and frequently we encounter crystals lacking centrosymmetry. Thus crystal polarity determination on a microscopic scale is becoming increasingly important in describing interface structures and the internal defects in small crystals. in many cases the polarity of a crystallite can be determined by convergent beam electron diffraction, CBED. Powerful alternatives are to monitor the electron induced x-ray emission, EDS, or electron energy losses, EELS, under channeling conditions. While the determination of the phase of the structure factors, and thus the determination of the crystal polarity, relies on many beam diffraction effects when the CBED technique is used, two-beam experiments provide information about the phase of the structure factor when localized EDS or EELS signals are detected under channeling conditions.The experimental conditions used to determine the polarity and absolute orientation from electron channeling are similar to those used in ALCHEMI experiments to locate small amounts of atoms by electron channeling.

Dopant Site Location by Electron Channeling in Ion Implanted Silicon

1983 ◽  
Vol 31 ◽  
Author(s):  
S. J. Pennycook ◽  
J. Narayan ◽  
O.W. Holland
Keyword(s):  
Electron Microscope ◽  
Electron Micrographs ◽  
Site Location ◽  
Electron Channeling ◽  
Ion Channeling ◽  
Stages Of Growth ◽  
Early Stages ◽  
Simple Ratio ◽  
Implantation Profile

ABSTRACTA simple ratio technique using the phenomenon of electron channeling can be used to measure the substitutional concentrations of dopants in semiconductors on a submicron scale.A comparison was made between electron and ion channeling measurements on Si-Sb alloy samples having a range of nonsubstitutional fractions of Sb.Good agreement was obtained but both measurements indicated considerably more nonsubstitutional dopant than could be accounted for by precipitates observed in electron micrographs. The discrepancy can be explained if the precipitates are coherent in the early stages of growth and have their planes located interstitially with respect to the Si planes. The sensitivity of the electron channeling measurements to the implantation profile was investigated and found to be small.The determination of local dopant profiles in the electron microscope is described.

scholarly journals Burgers Vector Determination of Threading Screw Dislocations in 4H-SiC via Forescattered Electron Channeling Contrast Imaging

2009 ◽  
Vol 15 (S2) ◽  
pp. 1018-1019
Author(s):  
ME Twigg ◽  
YN Picard ◽  
JD Caldwell ◽  
CR Eddy
Keyword(s):  
Contrast Imaging ◽  
Screw Dislocations ◽  
Burgers Vector ◽  
Electron Channeling

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Site determination of Mn atoms in Sn-Mn-Te alloy by electron channeling enhanced microanalysis

2021 ◽  
Vol 119 (24) ◽  
pp. 243906
Author(s):  
Yi Huang ◽  
Xiao Xu ◽  
Dongsheng He ◽  
Jiaqing He
Keyword(s):  
Electron Channeling

Electron channeling pattern determination of crystallinity and crystallographic orientation in YBa2Cu3O7−δ thin films

1991 ◽  
Vol 206 (1-2) ◽  
pp. 369-373 ◽  
Author(s):  
K.H. Young ◽  
T.W. James ◽  
McD. Robinson ◽  
A.H. Cardona ◽  
H. Suzuki ◽  
...  
Keyword(s):  
Thin Films ◽  
Crystallographic Orientation ◽  
Electron Channeling ◽  
Pattern Determination

Exact Determination of the Polar Direction in Lithium Trihydrogen Selenite Ferroelectric Crystal

2003 ◽  
Vol 42 (Part 1, No. 10) ◽  
pp. 6483-6485
Author(s):  
El-maghraby Mohamed El-Maghraby ◽  
Toshio Kikuta ◽  
Toshinari Yamazaki ◽  
Noriyuki Nakatani
Keyword(s):  
Ferroelectric Crystal ◽  
Polar Direction ◽  
Exact Determination

Electron Channeling Analysis and Z-C0ntrast Imaging of Dopants in Semiconductors

1985 ◽  
Vol 43 ◽  
pp. 296-299
Author(s):  
S. J. Pennycook
Keyword(s):  
Crystal Structure ◽  
Layer Structure ◽  
Bragg Reflection ◽  
Analytical Techniques ◽  
Orientation Dependence ◽  
Lattice Location ◽  
Electron Channeling ◽  
Thermally Processed

The determination of dopant distribution and lattice location are key elements in the characterization of ion-implanted, thermally processed semiconductors. We present here two analytical techniques for this purpose. The first is a channeling technique for the determination of substitutional fractions of dopants or impurities in any crystal structure, and the second is a means for imaging and elemental mapping of heavy elements in light materials, even if they are in solution.Atom Location by Electron Channeling AnalysisIt has only recently been realized that the orientation dependence of characteristic x-ray emission close to a Bragg reflection, long regarded as a hindrance to accurate microanalysis, can form the basis of a powerful lattice location technique. The first studies of this kind located trace elements in layer structure minerals, where it was known that the only possible sites for the impurity lay within the layer planes A and/or B. These restraints exclude many materials and here a generalization to any crystal structure is described.

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