If the intensity of two peaks in the X-ray pattern is the same, which peak is used to calculate the crystalline size in the Scherer formula? and why?
Dear Matin Akbari ,
to my opinion it is up to you.
From the counting statistics point of view they are quite equal.
You should take the results of both of them; so you can see any variation in the crystallite size estimation.
Please bear in mind that the Scherrer approach is a rough estimation of some kind of mean value of crystallite size and not more...
Thank you for your answer, your answer is completely correct, but in taken XRD pattern from the sample, two peaks with maximum intensity were seen and I was hesitant to use which peak to calculate the crystallite size? As we know, in the Scherer method, the maximum peak is used to measure crystallite size, but two maximum peaks are observed in the XRD pattern sample.
Dear Matin Akbari ,
just a remark:
'crystallinity' is different from 'crystallite size' and is not estimated from Scherrer equation/method.
It decribes the fraction of a sample which is crystalline. The counter part is the amorphous fraction.
Please see for example:
https://en.wikipedia.org/wiki/Crystallinity
But you may have errorneously written 'crystallinity' instead of 'crystallite size' in your answer above...
Dear Matin Akbari ,
In addition to Dr. Gerhard Martens' comment, the only necessary care is to be sure that the two peaks are not equal due to some texture and do not present any asymmetry. Preferred orientation, when present, may leave two distinct peaks about the same size; however, any data obtained by them are going to express different properties or behaviour. If present, the asymmetry may give completely unreal parameters unless you already have modeled the asymmetry by knowing the origin of the phenomenon.
Best regards,
WNM
Dear Dr. Gerhard Martens
Yes, you are right, I used crystallinity instead of crystallite size in typing the answer incorrectly and a typo occurred.
So two peaks with same intensity never occur in an X-ray pattern? And always in the X-ray pattern, one peak has maximum intensity?
then why two peaks with maximum intensity were seen in this x-ray pattern?? I was hesitant to use which peak to calculate the crystallite size. As we know, in the Scherer method, the maximum peak is used to measure crystallite size, but two maximum peaks are observed in the XRD pattern sample.
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