From the sharpness of peak we conclude whether it is amorphous or crystalline and from the appearance of extra peaks impurities are suggested. But these suggestions are qualitative. Could we establish a numerical value for the purity and particle size?
For particle size calculation you can use debye scherrer formula. And for the purity you check with jcpds data whether any impurity peaks present in the XRD pattern
If you have more than two or more than two phases in your sample then you can relate your purity with each other in quantitative manner. If there is no extra peak than your material then it itself is indication 100% phase purity (if no amorphous impurities are present).
XRD can not be useful in determination of particle size. But you can determine the crystallite size. you can use Scherrer formula to calculate crystallite size. Note that you have to use corrected FWHM for this calculation....
Dear Mr. Waqas Ali Shah
Yes we can. According to XRD plot we can determine particle size quantitatively by using Scherrer's equation.
t = (k*lambda)/(FWHM*cos theta)
k = shape factor (generally used 0.9), lambda = X-Ray wavelength has been used in XRD, FWHM = Full Width at Half Maximum of corresponding peak with the highest intensity (e.i., peak (311)). Cos theta = cos of angle for corresponding peak (i.e., (311)). You need reference plot according to your material. The reference can be found in JCPDS for certain card number.
If your XRD plot has the highest peak intensity of plane (311), so you can use this peak peak. Determining it's FWHM and the value of theta (be careful, it is not for 2 theta!).
In determining the purity of sample quantitatively, you can use volume ratio between your material and extra impurities. Let measure the intensity of all peak owned by your material (purposed material) and also the intensity of extra peaks impurity. For example: the total peak intensity of spinel ferrite ZnFe2O4 is 300 and the intensity of alpha-Fe2O3 phase is 20 (arbitrary unit), so the volume ratio can be calculated by using following equation:
% volume ratio of corresponding peak (certain phase) = the intensity of corresponding peak / (the total intensity of all peaks (material + purity)).
If you know the phases present in your sample and you have the crystallographic models of all of them you can perform a Rietveld refinement that allow to determine the percentages of the different phases, the amorphous content and also the crystallite size
There were some discussions on this matter already. Please, use the 'Search' functionality. E.g. https://www.researchgate.net/post/How_can_I_get_the_percent_of_crystallinity_from_Powder_XRD_data/1
https://www.researchgate.net/post/Can_we_obtain_information_about_size_like_micro_and_nano_meter_from_xrd_graph_of_a_compound
https://www.researchgate.net/post/It_is_possible_to_measure_crystallite_size_when_the_diffraction_peaks_have_low_intensity
And a general advice - do not use Scherrer's equation, in 99% of cases it will provide you with meaningless results.
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