alicia
Hello community,
I need to ask you a question about the usefulness of "Peak Phase" in the Topas program.
I am about to make a quantization and enter all the cif of the different phases, after making the adjustment I observe that some of the peaks are not filled with the adjustment and that is when I use peak phase and placing the cursor on the peaks that are not They have adjusted well I get a better adjustment, please, could someone tell me if I am modifying the quantization and if this use of the peak phase is not correct, please.
Thanks a lot,
Alicia
johnsoevans
I don't fully understand your question, but I think the answer is: yes, you will be influencing the quantitative analysis.
Accurate and precise quantitative analysis is very difficult to do well. You should look at chapters in (e.g.) Dinnebier and Billinge "Powder Diffraction" or Dinnebier, Leineweber and Evans "Rietveld Refinement" for some tips.
If your Rietveld model isn't explaining all the peak intensities then it's very unlikely that your quant will be correct. The fact that you're having to use a "peak phase" (this just fits missing intensity arbitrarily) suggests this is the case.
Remember also that even with a "perfect" Rietveld fit you will only be sensitive to crystalline components in the sample. There are also many issues related to sample preparation, sample absorption that can influence values. At the very least you should test your analysis on similar artificial samples of known composition.