X-Ray diffraction

  • Thread starter dg88
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  • #1
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Hello all,

I have a basic question with the theta-2theta technique in XRD. Here it is:

If I have a single crystal material and I perform the above mentioned characterization. Should I get one diffraction peak associated to the orientation of the bulk crystal or should I get many peaks. This doubt arises because of two reasons:
1)as we scan theta in a given range, the direction of the wave vector changes. This wave vector coincides with different lattice directions as we change theta.
2) The bulk crystal has all the crystal directions [hkl] within it. So if we do the Ewald construction, I feel that the wave vector sphere should intersect with more than one reciprocal lattice point rather than just one.

Thanks in advance
 

Answers and Replies

  • #2
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I am not familiar with XRD but TEM.
Based on the formula 2dsinθ=λ, I thought that many peaks will be obtained when we scan in a not small range.
 
  • #3
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Hello all,

I have a basic question with the theta-2theta technique in XRD. Here it is:

If I have a single crystal material and I perform the above mentioned characterization. Should I get one diffraction peak associated to the orientation of the bulk crystal or should I get many peaks. This doubt arises because of two reasons:
1)as we scan theta in a given range, the direction of the wave vector changes. This wave vector coincides with different lattice directions as we change theta.
2) The bulk crystal has all the crystal directions [hkl] within it. So if we do the Ewald construction, I feel that the wave vector sphere should intersect with more than one reciprocal lattice point rather than just one.

Thanks in advance
It depends on the radiation you use (and also the XRD system)
If it's monochromatic and you have a single crystal, it's very likely that in most positions you'll get no peaks. The crystal need to be rotated in 3D so more than one rotation axis is required. If yo have a powder diffraction setup, with only one axis, you'll need quite some experimenting to find the positions for the peaks.

If you use white radiation then you could get many peaks at once (Laue setup).
 

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