Low-Order Structure-Factor Amplitude and Sign Determination of an Unknown Structure AlmFe by Quantitative Convergent-Beam Electron Diffraction

It has been claimed that the effective Peierls stresses and mobilities of certain dislocations in TiAl are influenced by the anisotropy of bonding charge densities. This claim is based on the angular variation of electron charge density calculated by theory. It is important to verify the results of these calculations experimentally, and the present paper describes a series of such experiments. A description of the bonding charge density distribution in materials can be obtained by utilizing the charge deformation density (Δρ (r)) defined by(1) where V is the volume of the unit cell, Fobs is the experimentally determined low order structure factor and Fcalc is the structure factor calculated using the Hartree-Fock neutral atom model. To determine the experimental low order structure factors, a technique involving a combination of convergent beam electron diffraction (CBED) and electron energy loss spectroscopy (EELS) has been used.

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Quantitative Convergent Beam Electron Diffraction (CBED) measurements of low-order structure factors in metals

Electron Microscopy and Analysis 1997 ◽

10.1201/9781003063056-33 ◽

2022 ◽

pp. 129-132

Author(s):

M Saunders ◽

A G Fox

Keyword(s):

Electron Diffraction ◽

Convergent Beam Electron Diffraction ◽

Order Structure ◽

Beam Electron ◽

Structure Factors ◽

Convergent Beam ◽

Low Order

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Quantitative Convergent Beam Electron Diffraction Measurements of Low-Order Structure Factors in Copper

Microscopy and Microanalysis ◽

10.1017/s1431927603030319 ◽

2003 ◽

Vol 9 (5) ◽

pp. 379-389 ◽

Cited By ~ 10

Author(s):

Jesper Friis ◽

Bin Jiang ◽

John C.H. Spence ◽

Randi Holmestad

Keyword(s):

Electron Diffraction ◽

High Energy ◽

Convergent Beam Electron Diffraction ◽

Order Structure ◽

Band Theory ◽

Beam Electron ◽

Structure Factors ◽

A Charge ◽

Convergent Beam ◽

Low Order

Accurate low-order structure factors for copper metal have been measured by quantitative convergent beam electron diffraction (QCBED). The standard deviation of the measured structure factors is equal to or smaller than the most accurate measurement by any other method, including X-ray single crystal Pendellösung, Bragg γ-ray diffraction, and high-energy electron diffraction. The electron structure factor for the (440) reflection was used to determine the Debye-Waller (DW) factor. The local heating of the specimen by the electron beam is determined to be 5 K under the current illumination conditions. The low-order structure factors for copper measured by different methods are compared and discussed. The new data set is used to test band theory and to obtain a charge density map. The charge deformation map shows a charge surplus between the atoms and agrees fairly well with the simple model of copper 2+ ions at the atomic sites in a sea of free uniformly distributed electrons.

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Experimental Studies of Bonding Related Properties in Binary Intermetallics by Convergent Beam Electron Diffraction

MRS Proceedings ◽

10.1557/opl.2011.37 ◽

2011 ◽

Vol 1295 ◽

Author(s):

X. H. Sang ◽

A. Kulovits ◽

J. Wiezorek

Keyword(s):

Electron Diffraction ◽

Experimental Studies ◽

Convergent Beam Electron Diffraction ◽

Zone Axis ◽

Order Structure ◽

Electron Charge Density ◽

Beam Electron ◽

Structure Factors ◽

Different Temperatures ◽

Convergent Beam

ABSTRACTAccurate Debye-Waller (DW) factors of chemically ordered β-NiAl (B2, cP2, ${\rm{Pm}}\bar 3 {\rm{m}}$) have been measured at different temperatures using an off-zone axis multi-beam convergent beam electron diffraction (CBED) method. We determined a cross over temperature below which the DW factor of Ni becomes smaller than that of Al of ~90K. Additionally, we measured for the first time DW factors and structure factors of chemically ordered γ1-FePd (L10, tP2, P4/mmm) at 120K. We were able to simultaneously determine all four anisotropic DW factors and several low order structure factors using different special off-zone axis multi-beam convergent beam electron diffraction patterns with high precision and accuracy. An electron charge density deformation map was constructed from measured X-ray diffraction structure factors for γ1-FePd.

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Determination of the polarity of the GaAs (001) rosette arms by convergent beam electron diffraction

Microscopy of Semiconducting Materials 2003 ◽

10.1201/9781351074636-103 ◽

2018 ◽

pp. 445-448

Author(s):

L Largeau ◽

G Patriarche ◽

F Glas ◽

E Le Bourhis

Keyword(s):

Electron Diffraction ◽

Convergent Beam Electron Diffraction ◽

Beam Electron ◽

Convergent Beam

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Determination of space group of BaPb0.75Bi0.25O3 by convergent-beam electron diffraction

Physica C Superconductivity ◽

10.1016/s0921-4534(02)01259-5 ◽

2002 ◽

Vol 382 (4) ◽

pp. 422-430 ◽

Cited By ~ 2

Author(s):

Takuya Hashimoto ◽

Kenji Tsuda ◽

Junichiro Shiono ◽

Junichiro Mizusaki ◽

Michiyoshi Tanaka

Keyword(s):

Electron Diffraction ◽

Convergent Beam Electron Diffraction ◽

Beam Electron ◽

Space Group ◽

Convergent Beam

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High Sensitivity Convergent Beam Electron Diffraction for the Determination of the Tetragonal Distortion of Epitaxial Films

MRS Proceedings ◽

10.1557/proc-589-93 ◽

1999 ◽

Vol 589 ◽

Cited By ~ 1

Author(s):

C. Schuer ◽

M. Leicht ◽

T. Marek ◽

H.P. Strunk

Keyword(s):

Electron Diffraction ◽

High Sensitivity ◽

Diffraction Theory ◽

Gaas Layer ◽

Convergent Beam Electron Diffraction ◽

Epitaxial Films ◽

Tetragonal Distortion ◽

Beam Electron ◽

Convergent Beam

AbstractWe have optimized the sensitivity of convergent beam electron diffraction (CBED) by orienting the specimen such that the central (000) diffraction disc shows a pattern of defect lines that are most sensitive to tetragonal distortion. We compare the position of these lines in the experimentally obtained patterns with results from computer simulations, which need to be based on dynamical diffraction theory. In both experimental and simulated patterns the positions of the defect lines are determined by applying a Hough transformation. As a result of this optimized approach, we can measure the tetragonal distortion of a low temperature grown GaAs layer as low as 0.04%.

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