These are the XRD patterns for the same sample, but they seem different; one of them has broader peaks than the another, and when I count the size of the crystals using Scherrer equation, the difference is immense. The narrower peaks pattern gives results match the literature, but the another gives half of the size crystals known.
My questions:
How can I transfer the broader peaks pattern to narrower peaks pattern?
How can I count the size of crystals from each one?
Dear Fahad,
By same sample do you mean same material coated twice maintaining the deposition process parameters constant?
If XRD taken on same sample,
Is sample homogeneous?
Did you take XRD of the sample same day?
Dear Fahad,
XRD spectra can provide information about (i) amorphous, (ii) polycrystalline and , (iii) single crystal samples. A single crystal specimen in a Bragg-Brentano diffractometer would produce only one family of peaks in the diffraction pattern. A polycrystalline sample (right-hand-side image in your case) should contain thousands of crystallites. Therefore, all possible diffraction peaks should be observed.
The simplest answer to your question would be that from polycrystalline sample you have collected set of reflections belonging to atoms from different unit cells.
For single crystalline material, the X-rays will be scattered only in certain directions. Which will cause high intensity peaks with a narrow width (not always true other variables can play a role in this). Whereas for polycrystalline, the material consists of so many single crystals oriented in so many directions causing the X-rays to be scattered among a wide range of 2-Theta instead of high intensity narrow width peaks.
Dear Fahad Aljuaid ,
In addition to the comments of Dr. Azeez Barzinjy , the samples are significantly different in physical characteristics. Checking the experiment, they are even different in the occupation of the planes.
The left one is much more crystalline than the right diffraction; the signal peak gives clear evidence by the background counting ratio.
There is an evident texture at the left; the three peaks' high intensity compared with the remaining shallow peaks is unusual. Such a low-intensity peak would be expected only in materials such as the superstructure lattices in tetragonal material, generally caused by stacking fault.
Particle sizes are incredibly different; as mentioned, it would be clear that it has no sense to compare them just by inspecting the results. They are just quite different.
A heat-treatment may be useful at the sample (right). The procedure would aim to correct some effects, expulse some trapped impurities or solvent molecule, in other words, giving more nucleation time, and in the consecutive process, use a mortar to decrease the particle size after each heat-treatment.
That procedure would be useful in association with the other sample (left) for further comparison.
The best way to determine the particle size in each experiment is by fitting it, using Rietveld analysis, and calculate the XRD crystal size. It could be checked afterward by comparison with experimental laser particle size measurement, for instance.
Best regards,
WNM
Before I can say something meaningful about your XRD results, first a few questions need answers:
1. Could you give more information about your sample? What is the powder particle size? (this is not by definition the crystallite size).
2. Does your powder consists of single crystal particles?
3. How thick is the layer of particles in your experiment? One layer or much more? This is important in case you have large single crystals. They might orient preferentially leading to a preference for showing a subset of reflections.
4. What material?
5. In your first introduction you state that it are patterns from the same sample. Do you really show the diffractograms of precisely the same sample?
Using peak broadening as a measure for crystallite size only works for small sized (nano) crystallites. Else it is your device that determines the peak broadening.
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