X ray diffraction by kk sahu

Introduction
Definition
History
Principle
Instrumentation
Methods
Applications
Advantages
Limitation
Conclusion
References
X-ray diffraction (XRD) is one of the most important non-destructive tools to analyze all kinds of matter—ranging from fluids, to powders and crystals. From research to production and engineering, XRD is an indispensable method for materials characterization and quality control.
X-ray diffraction techniques are used for the identification of crystalline phases of various materials and the quantitative phase analysis subsequent to the identification.
X-ray diffraction techniques are superior in elucidating the three-dimensional atomic structure of crystalline solids.

1. 1 x-ray diffraction By KAUSHAL KUMAR SAHU Assistant Professor (Ad Hoc) Department of Biotechnology Govt. Digvijay Autonomous P. G. College Raj-Nandgaon ( C. G. )

2. SYNOPSIS Introduction Definition History Principle Instrumentation Methods Applications Advantages Limitation Conclusion References 2

3. INTRODUCTION X-ray diffraction (XRD) is one of the most important non-destructive tools to analyze all kinds of matter—ranging from fluids, to powders and crystals. From research to production and engineering, XRD is an indispensable method for materials characterization and quality control . X-ray diffraction techniques are used for the identification of crystalline phases of various materials and the quantitative phase analysis subsequent to the identification. X-ray diffraction techniques are superior in elucidating the three-dimensional atomic structure of crystalline solids. 3

4. DEFINITION The atomic plans of a crystal cause an incident beam of x-rays to interfere with one another as they leave the crystal. The phenomenon is called x-ray diffraction. 4

5. HISTORY X-ray were discovered in 1895 by the German physicist Wilhelm Conrad Rontgen and were so named because their nature was unknown at the time. He was awarded the Nobel Prize for physics in 1901. 1912: Max Theordor Felix von Laue (1879-1960) (U of Munich) thought that X-ray has a wavelength similar to interatomic distances in crystals and the crystal should act like a 3D diffraction grating. Along with Walter Friedrich (research assistant) and Paul Knipping (PhD grad student), he did the first diffraction experiment on CuSO4 crystal – Nobel Prize in Physics. 5

6. PRINCIPLE X-ray diffraction is based on constructive interference of monochromatic x-rays and a crystalline sample. These x-rays are generated by a cathode ray tube, filtered to produce monochromatic radiation, collimated to concentrate and directed towards the sample. The interaction of incident rays with the sample produces constructive interference when conditions satisfy Bragg’s law . 6

7. BRAGG’S LAW In  physics ,  Bragg's law , or  Wulff –Bragg's condition , a special case of  Laue diffraction , gives the angles for coherent and incoherent  scattering  from a crystal lattice. When  X-rays are incident on an  atom , they make the  electronic cloud  move as does any  electromagnetic wave . The  movement  of these  charges  re-radiates  waves  with the same  frequency , blurred slightly due to a variety of effects; this phenomenon is known As   Rayleigh scattering  (or elastic scattering). These re-emitted wave fields  interfere  with each other either constructively or destructively (overlapping waves either add up together to produce stronger peaks or are subtracted from each other to some degree), producing a diffraction pattern on a detector or film. The resulting wave interference  pattern  is the basis of  diffraction  analysis. This analysis is called  Bragg diffraction . 7

8. BRAGG’S EQUATION nΛ = 2d sinΘ where, Λ = the wavelength of the x-ray d = the spacing of the crystal layers (path difference) θ = the incident angle (the angle between incident ray and the scatter plane) n = an integer 8

9. production of x- rays collimator Monochromator Filter Crystal monochromator Detectors Photographic methods Counter methods INSTRUMENTATION 9

10.   PRODUCTION OF X- RAYS 10

11. COLLIMATOR 11

12. MONOCHROMATORS In order to do monochromatization 2 methods are available:- Filter Crystal monochromator Flat crystal monochromator Curved crystal monochromator 12

13. The x-ray intensities can be measured and recorded either by Photographic methods Counter methods Geiger – Muller tube counter Proportional counters Scintillation detector Solid state semiconductor detector Semi-conductor detectors DETECTORS 13

14. Geiger – Muller tube counter 14

15. Scintillation detector 15

16. Semi –conductor detectors 16

17. 17

18. X- RAY DIFFRACTION METHODS These are generally used for investigating the internal structures and crystal structures of various solid compounds. They are Laue’s photographic method Transmission method Back reflection method Bragg’s x- ray spectrometer method Rotating crystal method Powder method 18

19. Transmission Laue method 19

20. Bragg’s x-ray spectrometer method 20

21. Rotating crystal method 21

22. Powder crystal method 22

23. APPLICATION Structure of crystal Polymer characterization State of anneal in metals Particle size determination 23

24. ADVANTAGE It is a powerful and rapid technique. Less sample required. Unknown determination. 24

25. LIMITATION XRD also has size limitations. It is much more accurate for measuring large crystalline structures rather than small ones. 25

26. CONCLUSION For materials including metals, minerals, plastics, pharmaceuticals and semiconductors XRD apparatus provide highly accurate tools for non-destructive analysis. The diffraction systems are also supported by an extensive range of application software. 26

27. REFERENCES http://serc.carleton.edu>techniques https://www.omicsonline.org.>open http://www.rigaku.com>techniques 27