How's diffraction pattern modied by phonon perturbation?

In summary, the conversation discusses the effect of phonon perturbation on the diffraction pattern of a bcc lattice. It is mentioned that this perturbation can lead to a reduction in the amplitude of normal diffraction peaks and the appearance of Thermal Diffuse Scattering. The Debye-Waller factor is also brought up as a way to describe this reduction.
  • #1
leehoom
6
0
Hi there,
I have a problem on phonon perturbation's effect on diffraction pattern.

Assume atomic planes parallel to (100) of bcc lattice is periodically perturbed by phonon.

How will diffraction pattern be modified as a result of such perturbation? Will we see any diffraction peaks in addition to those seen for a unperturbed lattice?

Thanks!
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  • #2
You get a reduction in the amplitude of the normal diffraction peaks, usually described by a Debye-Waller factor, and in addition you get Thermal Diffuse Scattering.

http://en.wikipedia.org/wiki/Debye–Waller_factor

http://www.neutron.ethz.ch/education/Lectures/neutronfall/Lecture_4-2
 
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  • #3
M Quack said:
You get a reduction in the amplitude of the normal diffraction peaks, usually described by a Debye-Waller factor, and in addition you get Thermal Diffuse Scattering.

http://en.wikipedia.org/wiki/Debye–Waller_factor

http://www.neutron.ethz.ch/education/Lectures/neutronfall/Lecture_4-2
Thank you! It's really helpful.
 
Last edited by a moderator:

1. How does phonon perturbation affect diffraction patterns?

Phonon perturbation, or the presence of vibrations in a crystal lattice, can cause changes in the diffraction patterns of a material. This is because the vibrations can alter the distance between atoms and the angles at which they are arranged, resulting in a modified diffraction pattern.

2. Can phonon perturbation be observed in diffraction experiments?

Yes, phonon perturbation can be observed in diffraction experiments by analyzing the changes in the diffraction pattern. This can provide information about the vibrational properties of the material and its crystal structure.

3. Are there any specific materials or conditions in which phonon perturbation is more pronounced?

Yes, phonon perturbation is more pronounced in materials with lower atomic masses and weaker bonding forces. It is also more prominent at higher temperatures or when the material is under mechanical stress.

4. How can phonon perturbation be controlled or minimized in diffraction experiments?

Phonon perturbation can be controlled or minimized by conducting experiments at lower temperatures, using heavier elements in the material, or applying pressure to the sample. It can also be reduced by using advanced diffraction techniques that are less sensitive to phonon vibrations.

5. What impact does phonon perturbation have on the accuracy of diffraction analysis?

Phonon perturbation can significantly impact the accuracy of diffraction analysis, as it can cause shifts and distortions in the diffraction pattern. Therefore, it is important to account for phonon perturbations when analyzing diffraction data to ensure accurate results.

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