I grew CsPbBr3 on mica via CVD. When I measured XRD, the main peak on JCPDS was not present in my sample. Why is that?
* is mica peak(JCPDS No.00-001-1098). at 8.93, 17.72, 26.75, 35.88.
Due to JCPDS No.84-0464 CsPbBr3 the main peak is 22.414, and 31.908 but in picture there are no two peaks but only matched with 15.28 and 30.72.
Why is the strongest peak on JCPDS not present, but weaker peaks are detected in my sample?
Dear Jun Park ,
you deal with a film sample but not with a powder one; thus you will most propably suffer from preferred orientation of your crystallites...
One of the measures to reduce such artifacts is to use a spinning sample stage.
Best regards
G.M.
Yes, it looks like epitaxial growth. Minimization of interfacial tension would be the reason.
The other answers are good, but let me phrase them slightly differently.
Your layer could be building up epitaxially deriving its orientation from the substrate. That would lead to extreme preferred orientation.
You are using a powder diffractometer to characterize your material, but your sample is not an equi-axised powder. The sample is a highly oriented material. If your 100% plane was parallel to the sample surface, you would see its reflection. It apparently is not but is orientated at some other angle.
This is also a problem with rolled foils examined by powder-XRD. The grains take on an orientation and not all planes will be in a position to reflect. You may need to use a different type of diffractometer to examine such samples.
Dear Jun Park ,
for the missing of peaks due to the preferred orientation/texture issue you may have for example a look at Fig. 8 (page 9) of:
Article Back-to-Basics tutorial: X-ray diffraction of thin films
and the text therein...
Best regards
G.M.
Hi Jun Park,
Just had a look at the Back-To-Basics tutorial Gerhard pointed out. Do read that; it is very well done!
One more little point: although it is a good idea to spin the sample, it may not help. If there are no 100% intensity planes parallel to the surface, spinning will not make any difference - you still won't see any. Spinning does help when you have some oriented randomly, and you want to bring more into a detectable orientation.
You are completely right w.s.l. Boyer ,
in the worst case spinning will not help...
Rotation probably won't help, but I think the oblique texturing methodology in transmission XRD could help. If transmission measurements can be performed, this method could confirm the identification. The goniometer is just decentered.
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