The sample is not amorphous, it is crystalline. The literature reports distinct peaks. But in my sample, I am not getting a single peak. What can be the possible reason for this?
Dear Apoorva,
please check your system with a well known crystalline sample. You may gave got a misaligned XRD system.
can you share little more detail about your samples ?
have you thin film sample with glass substrate ?
Dear Apoorva
There is a lot of reason for this:
-Either you have not found the requested phase and therefore you have a peak mixed of starting materials
-Either you have the desired phase formation in addition to some traces of one of the starting products
Therefore, the mixture stoichiometry of the starting materials must be revised
I have checked the XRD system with standard Silicon sample, it seems to be in order. My samples are thin films of a diacetylene compound in PVA matrix. The Raman spectra corroborates with reported data but the XRD data is in complete contrast.
Dear Apoorva
This is might be possible that the thinkness of thin film is very low as compare to the penetration power of X-ray and XRD results showing you the diffraction patterns of PVA matrix (amorphous) instead diacetylene thinfilm.
Actually, I am not much familiar with organic materials and their XRDs but mostly similar things happen, when we deposit a thinfilm of nanometer range on glass substrate.
Solution:
This problem can be solved with GI-XRD.
Dear Apoorva,
what does it mean: ' diacetylene compound in PVA matrix' ?
Do you have made a thin film of diacetylene on PVA and then milled the sample?
In such a case the contribution of diacetylene with respect to PVA in your sample may be too small in order to see any diacetylene XRD signal.
What is the expected thickness of the film? The film may be too thin. Diacetylene is absorbing not that much (only consisting of C and H). In addition elastic x-ray scatter from C (and H) atoms also is not that much (~ Z). So very most of your XRD signal may arise from PVA.
What makes you confident that the diacetylen film is crystalline?
If it is crystalline you may suffer from preferrend orientation of your crystallites in the thin film.
Yes, I have made thin film of diacetylene on PVA and then milled the sample, the role of PVA is just to give strength to the film. I agree that PVA may the possible cause, because the content of diacetylene is less as compared to PVA. I may take the XRD of only diacetyelene next time, or keep the content of PVA less.
The thickness of films is around 5 micron. I guess that is not very thin. The literature reports the distinct peaks in diacetylene, that's why I was expecting similar results.
The reason for not having a peak in a sample is that you have no order in the crystalline network, that is, there is no periodicity, the reticular planes do not repeat in an orderly manner.
Dear Apoorva,
you may roughly estimate the diacetylen content of your sample by the ratio of your diacetylene film thickness (~5µm) and the thickness dPVA of your PVA substrate:
rel. content ~ 5µm/dPVA . I guess that with a ratio of smaller than about a few percent you won't really see the diacetylene.
Furthermore, as Said pointed out above, you have to have a sufficient order in the molecular arrangement of your diacetylene in order to get well pronounced XRD peaks. Otherwise you will get only small broad peaks (if any at all), which are not really detectable on the huge PVA XRD background when you have a poor relative content of the diacetylen in your sample.
Another thing for organic compounds IR and Raman spectroscopies are very useful tools for information and better to understand the problem.
Thank you so much for your valuable inputs. I shall take the XRD of diacetylene alone next time. Yes, I took its Raman spectra, it seems to be alright.
The synthesized substance must be amorphous form otherwise the xrd display peak if synthesized substance in crystalline it should shows vaious high intense pAseason .
The non-existence of DRX peak means that there is no plan (hkl) which is repeated in the three-dimensional network in an orderly fashion. This also means that there is no order in the compound studied. So it can be a glass or it can be a polymer. Your compound is a polymer
And generally behaves like amorphous. The best techniques are the IR or Raman or other method that can inform you about the mass of the polymer and the number of chains that it constitutes.
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