In a XRD pattern of spinel, lower angle peaks are shifted to right and higher angle peaks are shifted to left. I have tried refining a, b and c, however no improvement in it.
Please suggest me the way to consider these kind of shifts. Attached here the pattern.
Most of the instrumental parameters should give a sort of "rigid" shift of your peaks. In this case it might be possible that the reference structure you are using has not the correct symmetry with respect to your experimental data.
Have you tried to refine the error of peak displacement? If the sample is not properly aligned an angle dependent displacement could be present. It is clear that in your case a cubic structure could not explain this kind of displacement, having a single lattice parameters. As suggested by Lorenzo you could also try to change the crystal structure, maybe a tetragonal distortion could help to explain your experimental data.
I have tried refining peak displacement error. I need to understand the mathematics of rietveld more thoroughly I seems.
thanks Prof. Lorenzo and Prof. Marcella for your suggestions.
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