Is it any reliability in calculating the approximate value of atomic percentage of impurities in sample from XRD studies through dividing the integral part (meant as peaks areas) of dopant by integral part of the whole compound (impurity + host) from diffraction pattern?
No, to get reliable phase fractions of minor impurity phases you need to do a full pattern fit (Reitveld refinement). There are a number of free programs to do this that you can download (GSAS,FullProf, etc..). Here's a good site that links to tutorials as well as free downloads:
http://aps.anl.gov/Xray_Science_Division/Powder_Diffraction_Crystallography/index.html
OK, Thank You for the advice. But then, when I finally get the both Reitveld refinements of host and (known) impurity, what should I do?
Rietveld refinement helps to find out the phase and the quantitative information regarding the distribution of cations in tetrahedral. octahedral etc voids.
But, I feel it is difficult to find the phase and crystal structure information of the impurity phases, if more than one impurity phases exist.
When I was working on this type of problem I felt easy with the following method. I used Bruker D8 Advanced which has EVA soft ware which is a user friendly software. Possibly Full proof software can also be work but it may little tedious.
1) Take the slow scan XRD data (open your XRD spectra in EVA/)
2) open the periodic table and select the elements which are present in your sample
3) after that, give command to the software to shows all possible phases (in a separate window) that can be formed using that elements present in your sample
4) then select one by one compound in the window. when you select a compound a series of lines/peaks appear on the screen corresponding to that particular compound/phase on matching these with your Sample's XRD pattern you can get the various phases information.
5) By matching this way, primarily, you can come to know the possible impurity phases that are existing in your compound along with your desired phases with all the possible elements present in your sample.
6) Then after you can go much deeper analysis by Rietveld refinement as you primarily have the information about the impurity phases.
You may want to consider alternative methods to quantify impurities. Particularly if you have amorphous impurity phases. Perhaps consider XRF to gain an indication regarding the quantity of impurities in an oxide system.
This will work (XRF), but only if the elements in your impurity phase are not in your major phase. If you only want elemental analysis and not phase fractions, then ICP analysis will also work (assuming you already know all the trace elements in your sample). This can give you elemental information down to parts per billion depending on the element. If you are after phase fractions, though, x-ray or neutron diffraction will be the best technique.
Sateesh,
I believe he said it was a known impurity phase. In any case you are talking about very specific commercial software for a particular instrument, which most likely he does not have. There are many free software packages for peak indexing and phase indentification as well as refinement.
Please, remember! You will need at least 3-5% of impurity to make sure XRD detect it. For example, with you analyze a XRD pattern of commercial alumina, you are only see the corundum reflections, but as known that commercial alumina has some of SiO2, Fe2O3, MgO, etc etc. If you are talking about observed phases of impurity in your material, Rietveld method is an excelent way to quantify it. Another possibility, is a XRF analysis, than you can quantify (with patterns) almost all elements of periodicle table.
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