X-ray Powder Diffraction: Determine Structure of Crystal

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SUMMARY

X-ray powder diffraction is an effective method for determining the crystal structure of materials. By plotting the square root of the sine of the diffraction angles (theta) against the sum of the squares of the Miller indices (h, k, l), one can identify whether a sample exhibits face-centered cubic (fcc), body-centered cubic (bcc), or diamond structures. The relationship between these variables results in a straight line for the correct structure. To proceed, one must obtain the series of Miller indices for each structure type to create the necessary plots.

PREREQUISITES
  • Understanding of X-ray powder diffraction techniques
  • Familiarity with Miller indices in crystallography
  • Knowledge of structure factors in solid-state physics
  • Basic graph plotting skills using mathematical software
NEXT STEPS
  • Research how to calculate and obtain Miller indices for fcc, bcc, and diamond structures
  • Learn about the structure factor and its relevance in X-ray diffraction
  • Explore software tools for plotting mathematical functions, such as MATLAB or Python's Matplotlib
  • Study the mathematical derivation of the relationship between diffraction angles and Miller indices
USEFUL FOR

This discussion is beneficial for materials scientists, crystallographers, and researchers involved in solid-state physics who are looking to analyze crystal structures using X-ray powder diffraction techniques.

bosti
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Hello! X-ray powder diffraction can be used to determine the structure of crystal. I am given the diffraction angles (theta) for a sample and I am supposed to see if it has fcc, bcc or diamond structure. I read that if one plots sqr(sin(theta)) against ( sqr(h) +sqr(k) +sqr(l) ) where h, k, l are Miller indices one gets a straight line. So what I should do is plot for the series of Miller indices for fcc, bcc and diamond and see which gives a straight line. But I have no idea where to get the miller indices series from. Could you please help me? Thank you!
 
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bosti said:
Hello! X-ray powder diffraction can be used to determine the structure of crystal. I am given the diffraction angles (theta) for a sample and I am supposed to see if it has fcc, bcc or diamond structure. I read that if one plots sqr(sin(theta)) against ( sqr(h) +sqr(k) +sqr(l) ) where h, k, l are Miller indices one gets a straight line.
Correct. Do you understand why this is true, or what equation it is derived from?

So what I should do is plot for the series of Miller indices for fcc, bcc and diamond and see which gives a straight line. But I have no idea where to get the miller indices series from. Could you please help me? Thank you!
You must have learned about structure factor. If you have forgotten, look it up.
 

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