Dear colleagues,
When I read paper, the crystallite size can be calcukated by taking the XRD data with the highest intensity profile. Btw, in our research using Ag3PO4 photocatalyst, it observed at 2 thetha = 20-25° and Miller indice of [210]. However, I just wonder how the maximum peak intensity of X-ray could be a refference in the crystallite size determination? What's the basic information to support it?
Thank you.
Dear F. Febiyanto ,
you know that the peak size is derived from the peak width such as the full width at half maximum (FWHM) *.
The peaks with heighest height come here into play because from the peaks with the largest heights these height(s) (and thus the half of the height(s)) can be determined with the highest confidence due to minimum noise, which statistically affects the individual height(s). Noise goes with sqrt(N) with N being the counts of the peak height. The relative noise Nr (as the noise relative to the peak height) is a measure of the measurement uncertainty of the peak height:
Nr =sqrt(N)/N= 1/sqrt(N)
So for the heighest N of the peaks we have the lowest uncertainty in peak height determination, which directly affects the (lowest) uncertainty of FWHM calculation.
*) If not, you should get familiar with the Scherrer equation and the Williamsen-Hall plot, which can be used for the crystallite size determination; just 'google' for these buzz-words.
Good luck
Dear F. Febiyanto ,
you know that the peak size is derived from the peak width such as the full width at half maximum (FWHM) *.
The peaks with heighest height come here into play because from the peaks with the largest heights these height(s) (and thus the half of the height(s)) can be determined with the highest confidence due to minimum noise, which statistically affects the individual height(s). Noise goes with sqrt(N) with N being the counts of the peak height. The relative noise Nr (as the noise relative to the peak height) is a measure of the measurement uncertainty of the peak height:
Nr =sqrt(N)/N= 1/sqrt(N)
So for the heighest N of the peaks we have the lowest uncertainty in peak height determination, which directly affects the (lowest) uncertainty of FWHM calculation.
*) If not, you should get familiar with the Scherrer equation and the Williamsen-Hall plot, which can be used for the crystallite size determination; just 'google' for these buzz-words.
Good luck
If there is only single broad peak between 2-theta (20-25), then your substance in amorphous state. A major peak should be observed in 33, 36 and so on for Ag3PO4 .
Determination of Size and Strain using the Williamson-Hall Plot is more accurate. And if you are familiar with the Redfield method, you can use refinement software like Jana2006 to calculate it.
see this link : http://pd.chem.ucl.ac.uk/pdnn/peaks/sizedet.htm
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