How can we determine/separate impurity through pxrd data.
If single crystal x ray diffraciton data is available., can we write cell parameter.
suggest paper related to this please.
To perform the phase analysis, you have to calculate the theoretical PXRD pattern on the basis of single-crystal XRD data (such an option is available in the majority of common crystal structure visualization software - e.g., Mercury or Diamond). You have to compare your experimental profile with the calculated one; extra peaks should be treated as impurities.
- I am not sure if there is any specific paper on this point, since PXRD analysis is a century-old routine procedure. You may search for any paper dedicated to the PXRD characterization of compounds and materials
From a PXRD pattern two main contributes can be identified: amorphous and crystalline.
Qualitative Phase Analysis can be performed by comparing the experimental PXRD with the known crystal phases that are stored in crystallographic databases such as COD, PDF, ICSD and CCDC. In this way, you can identify the presence of one or more crystal phases in your sample and gain some insights about its pureness.
Once all the crystal phases have been identified the next step is to perform a Quantitative Phase Analysis for which I recommend the Rietveld method. An excellent book that I have recently read is from Prof. John Evans: Rietveld Refinement – Practical Powder Diffraction Pattern Analysis using TOPAS (https://doi.org/10.1515/9783110461381). It is focused on the Rietveld refinement with TOPAS but it contains all the fundamentals of powder diffraction.
Please note that the analysis of the amorphous content is not trivial as you do not have information about its chemical composition. My suggestion is to perform some complementary analysis such as XRF that might be useful in some cases.
PXRD analysis give information about the mean composition of the bulk rather than a Single-Crystal XRD that is typically used to determine the crystal structure of unknown samples.
To answer you question on cell parameters – of course if you have a CIF file all of them must be in it.
As suggested by Mikhail Kendin to calculate the powder pattern from SC-XRD data with Mercury just open the CIF and go to: Calculate>Powder Pattern
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