- #1
madhusoodan
- 14
- 0
Why almost every crystal system has peak around 32 degree (2 theta) ?
XRD peak position near 32 degree
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Discussion Overview
The discussion revolves around the observation of X-ray diffraction (XRD) peak positions, specifically the claim that many crystal systems exhibit a peak around 32 degrees (2 theta). Participants explore the validity of this claim, the factors influencing peak positions, and the implications of their observations.
Discussion Character
- Debate/contested
- Technical explanation
Main Points Raised
- One participant questions the validity of the claim that "almost every crystal" has a peak around 32 degrees, suggesting that such a broad statement lacks empirical support.
- Another participant notes that the peak position is dependent on the wavelength of the X-rays used, implying that the 32-degree peak may not hold special significance.
- A participant shares their experience with XRD on MgO, indicating that no peak around 32 degrees was observed in their results, thus challenging the original claim.
- There is a suggestion that the original poster should clarify their basis for the claim regarding the 32-degree peak and the systems they studied.
- One participant acknowledges that while many crystalline materials belong to 230 space groups, the peak positions can vary significantly, and not all systems will exhibit peaks in the same range.
- Another participant emphasizes that changing the X-ray wavelength can alter the peak positions, further questioning the relevance of the 32-degree observation.
Areas of Agreement / Disagreement
Participants express disagreement regarding the claim of a common peak at 32 degrees, with some challenging its validity and others questioning the empirical basis for the assertion. The discussion remains unresolved, with multiple viewpoints presented.
Contextual Notes
Participants highlight the dependence of peak positions on experimental conditions, such as X-ray wavelength, and the variability among different crystalline structures, indicating that the original claim may not be universally applicable.
- #2
nasu
Homework Helper
- 4,472
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There are tens of thousand(s) (at least) known crystalline materials. How many of these have you checked to make the claim that "almost every crystal"?
Of course, if you make the "around" wide enough it will true for any angle.
Besides, the angle depends on the wavelength of the x-rays. Change your x-ray tube and the angles will change. So the 32 degree value cannot have any special meaning.
Of course, if you make the "around" wide enough it will true for any angle.
Besides, the angle depends on the wavelength of the x-rays. Change your x-ray tube and the angles will change. So the 32 degree value cannot have any special meaning.
- #3
- 32,819
- 4,723
madhusoodan said:
I agree with nasu. This is an ambiguous, and frankly, meaningless claim.
I did an XRD a couple of months ago on MgO. It looks almost like this:
See any 32-degree peak anywhere?
Zz.
Last edited by a moderator:
- #4
nasu
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@madhusoodan
I think it will be interesting to see how did you come to this impression. What systems did you study by XRD?
Maybe they all have very similar structures.
I think it will be interesting to see how did you come to this impression. What systems did you study by XRD?
Maybe they all have very similar structures.
- #5
madhusoodan
- 14
- 0
@nasu
However, all ten thousand (s) of crystalline materials fall into 230 space groups only. out of that, many systems have peaks near 32 degrees. Very less number of systems have peak in the range of 20-30.
I should not have used 'almost every'.
However, all ten thousand (s) of crystalline materials fall into 230 space groups only. out of that, many systems have peaks near 32 degrees. Very less number of systems have peak in the range of 20-30.
I should not have used 'almost every'.
- #6
nasu
Homework Helper
- 4,472
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Would you care to explain how you got this idea with the 32 degree angle? Otherwise there is no base for discussion.
It's based on your own XRD measurements on some systems?
The mention of 230 space group is not relevant. They can be all cubic crystals and still have all different peaks.
It's based on your own XRD measurements on some systems?
The mention of 230 space group is not relevant. They can be all cubic crystals and still have all different peaks.
- #7
- 32,819
- 4,723
.. or, as nasu has stated earlier, you can use the identical crystal and just change the x-ray wavelength, and the peak position changes!
@madhusoodan, have you actually performed this XRD experiment yourself?
Zz.
@madhusoodan, have you actually performed this XRD experiment yourself?
Zz.
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