X-Ray Diffraction
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X-ray diffraction is a non-destructive technique used to analyze the structure of crystalline materials. Bragg's law explains how x-rays interfere and diffract when hitting the regular atomic planes of a crystal. In 1914, Knipping and Von Laue discovered that crystals act as three-dimensional diffraction gratings for x-ray wavelengths similar to the spacing of planes in the atomic lattice. Bragg later provided a simple and precise explanation for the diffraction patterns seen in crystal structures. Today, x-ray diffraction is used to determine crystal structures, grain size, strain, and other structural properties of materials.
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 = 2dsinθ
- 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 = 2AB --------(2) But, AB = dsinθ --------(3) From equation (2) we get, λ = 2 ( dsinθ ) λ = 2dsinθ (by equation (3)) λ = 2dsinθ 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.
- 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 3D distribution of atom in space.
- 13. (1) Laue’s photographic method:- Fig:- Laue’s method Fig:- Laue pattern
- 15. (2) Powder method:- Fig:- powder crystal method.
- 16. 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.
- 17. USES:- Obtain X-ray diffraction pattern. Measure d-spacing. Obtain integrated intensities.
- 18. ERRORS:- Speciment displacement. Errors in zero position. Instrument misalingnment.
- 19. CONCLUSION:- Non- destructive, fast, easy sample preparation. High-accuracy for d-spacing calculation. Standard are available for thousand of material systems.
- 20. References:- Chatwal G.R., Instrumental method of chemical analysis, 1st edition, Himalaya Publishing house; 2004, page No. 2.303 – 2.332 Sharma B.K., Instrumental method of chemical analysis, 24th edition, Goel Publishing house; 2006, page No. 329- 359 Gurtu-Gurtu , Biophysical chemistry , 5th edition, 2010 page No. 195-202