X-Ray Diffraction

X-Ray Diffraction

1. X-RAY DIFFRACTION By- Manish Sahu M.Sc. Chemistry (Final) Sp.- Physical Chemistry

2. CONTENTS Introduction History Bragg’s law X-Ray Diffraction Basis of crystallography Seven crystal system Method of X-Ray diffraction Basis features of typical x-ray Application Uses Error Conclusion References

3. Introduction:- It is a non-destructive analytical techniques used to study the structure, composition and physical properties of materials. Bragg’s law is used to explain the interference pattern of X-rays. It is commonly known as X-ray diffraction or X-ray wave interference.

4. History:- In 1895 discovery of X-ray production by Willem Roentgen. In 1914 discovery of X-ray diffraction pattern by knipping and Von Laue. In 1915 theory of X-ray diffraction pattern by Bragg.

5. Bragg’s law λ = 2dsin θ

6. …………… Crystalline material consist of parallel rows of atoms separated by unique distances. Diffraction occurs when a beam enter a crystalline substance and is scattered. Direction and intensity of diffraction depends on orientation of the crystal lattice with radiation.

7. DERIVATION Since we know that λ = AB + BC --------(1) But, AB = BC λ = 2 AB --------(2) But, AB = dsin θ --------( 3) From equation (2) we get, λ = 2 ( dsin θ ) λ = 2 dsin θ (by equation (3)) λ = 2 dsin θ This equation is known as Bragg’s equation.

8. X-RAY DIFFRACTION:- Non distractive analytical technique for identification and quantitative determination of various crystalline from known as phases . Identification is achieved by comparing the X-ray diffraction pattern. The atomic planes of a crystal cause an incident beam of X-ray to interference with one another as they leave the crystal. This phenomenon is called X-ray diffraction.

9. Fig:- X-ray diffraction

10. BASIC OF CRYSTALLOGRAPHY:- A crystal consist of periodic arrangement of the unit cell into a lattice . A unit cell can contain a single atom or atom in a fixed rearrangement . A crystal lattice is a regular 3 D distribution of atom in space.

11. SEVEN CRYSTAL SYSTEM:-

12. (1) Laue’s photographic method:- Fig:- Laue’s method Fig:- Laue pattern

13. (2) Powder method:- Fig:- powder crystal method.

14. APPLICATION:- It is a non distractive technique. To determine crystalline phases and orientation . To determine the structural properties such as Grain Size Strain Shape Lattice parameters . To determine atomic arrangement.

15. USES:- Obtain X-ray diffraction pattern . Measure d-spacing. Obtain integrated intensities .

16. ERRORS:- Speciment displacement. Errors in zero position. Instrument misalingnment.

17. CONCLUSION:- Non- destructive, fast, easy sample preparation. High-accuracy for d-spacing calculation. Standard are available for thousand of material systems.

18. References:- Chatwal G.R . , Instrumental method of chemical analysis, 1 st edition, Himalaya Publishing house; 2004 , page No. 2. 303 – 2. 332 Sharma B.K. , Instrumental method of chemical analysis, 24 th edition, Goel Publishing house; 2006 , page No. 329 - 359 Gurtu-Gurtu , Biophysical chemistry , 5th edition, 2010 page No. 195-202