# Powder diffraction

#### bosti

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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#### Gokul43201

Staff Emeritus
Gold Member
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 learnt about structure factor. If you have forgotten, look it up.

"Powder diffraction"

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