When doping in polycrystalline materials, it normally shifts the XRD diffraction peaks. Is it possible to know how much doping concentration using Rietveld method to fit XRD patterns?.
If your unit cell is changing with doping and you cannot see any impurity phase in your sample then it means that all of the dopant is going into the main phase. However, sometimes it is more complex when two similar phases are formed with overlapping peaks. So you will have to be careful in your Rietveld analysis.
If your doping material promove the formation of second phases or minority phases, yes, is possible to quantify it by Rietveld analysis.
The formation of a crystalline solid solution might result in change of unit cell dimension according to the Vegard's law, which is visible as a shift of the diffraction peaks. In this case a simple Le Bail or Pauly refinement would be sufficient. If the guest does not produce clear shift as in the case of inclusion compounds a refinement of the peak intensities is required that would be successful only with quality diffraction patterns. In any case I suggest to verify your results by chromatography, EDX, elemental analysis etc...
The integrated intensity of the reflections will also change, as the occupancy of dopant atoms as well as their locations within the unit cell will modify the structure factors.
doping is intercalating the dopant in the cavity of the anion or cation in the unit cell. You have to use elemental analysis to show the dopant concentration. XRD based methods work on phase changing. If there is a new peak correspond to the dopant, we can conclude that the dopant concentration is higher than the dopant limitation. So you should analyze the last sample that doesn't show the new peak
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