Presentation is loading. Please wait.

Presentation is loading. Please wait.

PASI Santiago, Chile July 2006 1 Eades / Convergent-Beam Diffraction: II Convergent-beam electron diffraction Applications.

Published byRebecca Nicholson Modified over 8 years ago

Similar presentations

Presentation on theme: "PASI Santiago, Chile July 2006 1 Eades / Convergent-Beam Diffraction: II Convergent-beam electron diffraction Applications."— Presentation transcript:

1 PASI Santiago, Chile July 2006 1 Eades / Convergent-Beam Diffraction: II Convergent-beam electron diffraction Applications

2 PASI Santiago, Chile July 2006 2 Eades / Convergent-Beam Diffraction: II Bragg’s Law

3 PASI Santiago, Chile July 2006 3 Eades / Convergent-Beam Diffraction: II Applications - in common with spot patterns 1Lattice spacings 2Unit cell 3Orientation

4 PASI Santiago, Chile July 2006 4 Eades / Convergent-Beam Diffraction: II Applications - special to CBED Established 1Crystal symmetry 2Local strain 3Direct phase identification 4Thickness

5 PASI Santiago, Chile July 2006 5 Eades / Convergent-Beam Diffraction: II Applications - special to CBED Advanced 1 Crystal structure determination 2Bonding measurement 3Phase determination 4Improved defect analysis

6 PASI Santiago, Chile July 2006 6 Eades / Convergent-Beam Diffraction: II Advanced Techniques The Tanaka methods –The techniques LACBED Other variations (CBIM, SA-CBED) –Applications Spatial variation Defect analysis Other Techniques –Coherent CBED –Energy filtering

7 PASI Santiago, Chile July 2006 7 Eades / Convergent-Beam Diffraction: II Lattice Spacings The lattice spacing is determined from the distance between the diffracted beams. In spot patterns it is the distance between spots. In convergent-beam patterns it is the distance between discs. These are generally equally accurate.

8 PASI Santiago, Chile July 2006 8 Eades / Convergent-Beam Diffraction: II FeS2 [110] K-C Hsieh

9 PASI Santiago, Chile July 2006 9 Eades / Convergent-Beam Diffraction: II Unit Cell Determination If a very short camera length is used, the unit cell can be determined, in principle, from a single diffraction pattern. In practice this may be tricky. The centering of the Bravais lattice can be easily obtained at a suitable zone axis.

10 PASI Santiago, Chile July 2006 10 Eades / Convergent-Beam Diffraction: II

11 PASI Santiago, Chile July 2006 11 Eades / Convergent-Beam Diffraction: II Orientation If the diffraction pattern is indexed, the orientation of the sample is determined. A selected area pattern can determine the orientation to within a few degrees. In convergent-beam diffraction additional information, from details in the discs or from Kikuchi lines, gives the result to a fraction of a degree.

12 PASI Santiago, Chile July 2006 12 Eades / Convergent-Beam Diffraction: II Symmetry The determination of the symmetry of a crystalline specimen is one of the most powerful applications of convergent-beam diffraction. It is valuable both to identify known phases and to determine the symmetry of new phases.

13 PASI Santiago, Chile July 2006 13 Eades / Convergent-Beam Diffraction: II

14 PASI Santiago, Chile July 2006 14 Eades / Convergent-Beam Diffraction: II Pyrite [001] K-C Hsieh

15 PASI Santiago, Chile July 2006 15 Eades / Convergent-Beam Diffraction: II Strain from HOLZ lines Limitations –The strain must be uniform through the thickness of the specimen. –The result is for the strain in the thin foil - not the strain in the original sample. –Results are relative not absolute without dynamical calculation.

16 PASI Santiago, Chile July 2006 16 Eades / Convergent-Beam Diffraction: II

17 PASI Santiago, Chile July 2006 17 Eades / Convergent-Beam Diffraction: II

18 PASI Santiago, Chile July 2006 18 Eades / Convergent-Beam Diffraction: II

19 PASI Santiago, Chile July 2006 19 Eades / Convergent-Beam Diffraction: II

20 PASI Santiago, Chile July 2006 20 Eades / Convergent-Beam Diffraction: II

21 PASI Santiago, Chile July 2006 21 Eades / Convergent-Beam Diffraction: II

22 PASI Santiago, Chile July 2006 22 Eades / Convergent-Beam Diffraction: II

23 PASI Santiago, Chile July 2006 23 Eades / Convergent-Beam Diffraction: II Phase Identification All convergent-beam zone axis patterns are unique and serve to identify phases. You must educate your eye. Limitations –The patterns do change with thickness –The uniqueness is not absolute.

24 PASI Santiago, Chile July 2006 24 Eades / Convergent-Beam Diffraction: II V 3 Si Doug Konitzer

25 PASI Santiago, Chile July 2006 25 Eades / Convergent-Beam Diffraction: II InP [100] G. Rackham

26 PASI Santiago, Chile July 2006 26 Eades / Convergent-Beam Diffraction: II M 23 C 6 [110]

27 PASI Santiago, Chile July 2006 27 Eades / Convergent-Beam Diffraction: II Ni 3 Al [110] S. Court

28 PASI Santiago, Chile July 2006 28 Eades / Convergent-Beam Diffraction: II Ni 3 Al [110] S. Court

29 PASI Santiago, Chile July 2006 29 Eades / Convergent-Beam Diffraction: II Thickness The method uses two-beam conditions. Some care must be taken in the analysis. The thickness is for the crystalline part of the sample only.

30 PASI Santiago, Chile July 2006 30 Eades / Convergent-Beam Diffraction: II

31 PASI Santiago, Chile July 2006 31 Eades / Convergent-Beam Diffraction: II

32 PASI Santiago, Chile July 2006 32 Eades / Convergent-Beam Diffraction: II

33 PASI Santiago, Chile July 2006 33 Eades / Convergent-Beam Diffraction: II Crystal Structure The phase problem Crystal structure determination Bonding measurement

34 PASI Santiago, Chile July 2006 34 Eades / Convergent-Beam Diffraction: II Crystal Potential

35 PASI Santiago, Chile July 2006 35 Eades / Convergent-Beam Diffraction: II Because of the complex interference between diffracted beams in dynamical electron diffraction, electron diffraction intensities are very sensitive to small changes in V g. Electron diffraction can thus determine bonding electron densities - but the calculations are complicated.

36 PASI Santiago, Chile July 2006 36 Eades / Convergent-Beam Diffraction: II Midgley, Saunders, Vincent and Steeds Ultramicroscopy 59 (1995) 1-13

37 PASI Santiago, Chile July 2006 37 Eades / Convergent-Beam Diffraction: II Midgley, Saunders, Vincent and Steeds Ultramicroscopy 59 (1995) 1-13

38 PASI Santiago, Chile July 2006 38 Eades / Convergent-Beam Diffraction: II Tanaka, Terauchi, Tsuda and Saitoh CBED IV 2002

39 PASI Santiago, Chile July 2006 39 Eades / Convergent-Beam Diffraction: II Tanaka, Terauchi and Tsuda CBED III 1994

40 PASI Santiago, Chile July 2006 40 Eades / Convergent-Beam Diffraction: II The Tanaka Methods Traditional microscopy taught that the microscope should be focussed on the specimen or on the diffraction pattern in the back focal plane. Tanaka liberated us and gave rise to a family of new techniques by telling us to look in other places.

41 PASI Santiago, Chile July 2006 41 Eades / Convergent-Beam Diffraction: II

42 PASI Santiago, Chile July 2006 42 Eades / Convergent-Beam Diffraction: II GaAs [100] K. Christenson

43 PASI Santiago, Chile July 2006 43 Eades / Convergent-Beam Diffraction: II Ni 3 Mo

44 PASI Santiago, Chile July 2006 44 Eades / Convergent-Beam Diffraction: II Ni3Mo BF Tanaka pattern

45 PASI Santiago, Chile July 2006 45 Eades / Convergent-Beam Diffraction: II Al layer on GaAs Tanaka Group

46 PASI Santiago, Chile July 2006 46 Eades / Convergent-Beam Diffraction: II Defect Analysis Large-Angle Convergent-Beam patterns provide an improved method of determining the Burgers vectors of dislocations. (And characterizing other defects.) The dislocations have to be well separated.

47 PASI Santiago, Chile July 2006 47 Eades / Convergent-Beam Diffraction: II Fe,30Ni,19Cr [114] Cherns and Preston

48 PASI Santiago, Chile July 2006 48 Eades / Convergent-Beam Diffraction: II Fe,30Ni,19Cr [114] Cherns and Preston

49 PASI Santiago, Chile July 2006 49 Eades / Convergent-Beam Diffraction: II Fe,30Ni,19Cr [114] Cherns and Preston

50 PASI Santiago, Chile July 2006 50 Eades / Convergent-Beam Diffraction: II Si Tanaka Group

51 PASI Santiago, Chile July 2006 51 Eades / Convergent-Beam Diffraction: II My apologies to those whose pictures are not acknowledged because I do not remember where they came from. All the Ni 3 Mo pictures are Mike Kaufman’s work.

Download ppt "PASI Santiago, Chile July 2006 1 Eades / Convergent-Beam Diffraction: II Convergent-beam electron diffraction Applications."

Similar presentations

References on convergent-beam diffraction. Contents: General book Specific topics I Specific topics II Eades articles.

References on convergent-beam diffraction. Contents: General book Specific topics I Specific topics II Eades articles.
(see Bowen & Tanner, High

(see Bowen & Tanner, High
XII. Electron diffraction in TEM

XII. Electron diffraction in TEM
Chap 8 Analytical Instruments. XRD Measure X-Rays “Diffracted” by the specimen and obtain a diffraction pattern Interaction of X-rays with sample creates.

Chap 8 Analytical Instruments. XRD Measure X-Rays “Diffracted” by the specimen and obtain a diffraction pattern Interaction of X-rays with sample creates.
X-ray Diffraction. X-ray Generation X-ray tube (sealed) Pure metal target (Cu) Electrons remover inner-shell electrons from target. Other electrons “fall”

X-ray Diffraction. X-ray Generation X-ray tube (sealed) Pure metal target (Cu) Electrons remover inner-shell electrons from target. Other electrons “fall”
Electron Diffraction - Introduction Electron diffraction is an important method to characterize materials. The textbook, Transmission Electron Microscopy,

Electron Diffraction - Introduction Electron diffraction is an important method to characterize materials. The textbook, Transmission Electron Microscopy,
Do it with electrons ! II.

Do it with electrons ! II.
Convergent-beam electron diffraction

Convergent-beam electron diffraction
What is diffraction? Diffraction – the spreading out of waves as they encounter a barrier.

What is diffraction? Diffraction – the spreading out of waves as they encounter a barrier.
Nanochemistry NAN 601 Dr. Marinella Sandros

Nanochemistry NAN 601 Dr. Marinella Sandros
Technology for a better society 1 Imaging defects and contours/effects.

Technology for a better society 1 Imaging defects and contours/effects.
Yifan Cheng Department of Biochemistry and Biophysics University of California San Francisco Electron Diffraction of 2D crystals - principle and data collection.

Yifan Cheng Department of Biochemistry and Biophysics University of California San Francisco Electron Diffraction of 2D crystals - principle and data collection.
Internal – External Order We described symmetry of crystal habit (32 point groups) We also looked at internal ordering of atoms in 3-D structure (230 space.

Internal – External Order We described symmetry of crystal habit (32 point groups) We also looked at internal ordering of atoms in 3-D structure (230 space.
Fourier Transforms and Images

Fourier Transforms and Images
Lecture 2.1 Crystalline Solids. Poly-crystalline solids - Grains Mono-crystalline solids- Whiskers, Wafers.

Lecture 2.1 Crystalline Solids. Poly-crystalline solids - Grains Mono-crystalline solids- Whiskers, Wafers.
CHAPTER 2 : CRYSTAL DIFFRACTION AND PG Govt College for Girls

CHAPTER 2 : CRYSTAL DIFFRACTION AND PG Govt College for Girls
Crystallography and Diffraction Techniques Myoglobin.

Crystallography and Diffraction Techniques Myoglobin.
Solid State Physics 2. X-ray Diffraction 4/15/2017.

Solid State Physics 2. X-ray Diffraction 4/15/2017.
Structure of thin films by electron diffraction János L. Lábár.

Structure of thin films by electron diffraction János L. Lábár.
Yat Li Department of Chemistry & Biochemistry University of California, Santa Cruz CHEM 146C_Experiment #3 Identification of Crystal Structures by Powder.

Yat Li Department of Chemistry & Biochemistry University of California, Santa Cruz CHEM 146C_Experiment #3 Identification of Crystal Structures by Powder.

Similar presentations

Ads by Google