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X-Ray Measurement Methods From Chapter 6 of Textbook 2 and other references Diffractometer Hull/Debye-Scherrer method Pinhole method Laue Method Rotating.

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Presentation on theme: "X-Ray Measurement Methods From Chapter 6 of Textbook 2 and other references Diffractometer Hull/Debye-Scherrer method Pinhole method Laue Method Rotating."— Presentation transcript:

1 X-Ray Measurement Methods From Chapter 6 of Textbook 2 and other references Diffractometer Hull/Debye-Scherrer method Pinhole method Laue Method Rotating Crystal Method http://www.stanford.edu/group/glam/xlab/MatSci162_ 172/LectureNotes/06_Geometry,%20Detectors.pdf

2 S: source; C: specimen; H: goniometer; O: rotation axis; A, B: slits for collimation; F: slit; G: detector; E and H can be mechanically; coupled  2  and  relation; Schematics of a typical X-ray diffractometer:

3 focusing monochromator CM = 2R, OC = R Cut off the crystal behind the dotted line to a radius R

4 http://cheiron2008.spring8.or.jp/lec_text/Sep.30/2008_T.Matsushita_1.pdf

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11 X-ray Optics: Bragg-Brentano diffractometers According to Euclid: “the angles in the same segment of a circle are equal to one another” and “the angle at the center of a circle is double that of the angle at the circumference on the same base, that is, on the same arc”.

12 Modern Bragg-Brentano laboratory diffractometer

13 Parallel beam geometry in Debye-Scherrer mode using a double monochromator (DM) and an analyzer crystal

14 Polycrystal Single crystal

15 An ideal powder sample many crystallites in random orientations; smooth and constant distribution of orientations; Crystallites < 10 μm Sample preparation: There are many methods of preparing samples: – Sample should normally be ground to < 10 μm – Sample may be sieved to avoid large or small crystallites – Sample may be loaded into a holder by pressing from the back while using a slightly rough surface at the front – Sample may be pressed in from the front – Sample may be mixed with a binder (epoxy or similar material) and then cut and polished to give a suitable surface

16 Hull/Debye-Scherrer method: R S S 22 22 2  =S/R Film

17 hole Film hole 22 22 22 22 S S 2S S S 22 R

18 Film hole 22 22 22 S 22 R and Resolving power

19 http://www.stanford.edu/group/glam/xlab/MatSci162_172 /LectureNotes/06_Geometry,%20Detectors.pdf

20 B S r1r1 F 22 A B r2r2 F 180 o -2  D D tan2  = r 1 /Dtan(180 o -2  = r 2 /D C C A Incident X-Ray Pinhole photographs monochromatic or white radiation and powder sample Laue methode: white radiation and single crystal

21 http://202.141.40.218/wiki/index.php/Unit- 2:_Introduction_to_X-ray_diffraction Rotating Crystal Method

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23 Concept of Ewald Sphere and Diffraction

24 Wavelength: incident beam = diffracted beam Magnitude of k  the same = 1/. Diffraction condition:  k = G 2B2B 2  B  k = G

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26 Diffraction Methods: Method  Laue Variable fixed Rotating crystal Fixed Variable Powder Fixed Variable  vaied  reciprocal lattice is rotated or Ewald sphere is rotated

27 Reciprocal lattice of polycrystalline sample

28 Features of Rigaku TTRAX Ⅲ

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