If two XRD patterns Bragg diffraction position are same but the intensity of highest peak position is different then could it be consider as same structure?
If peak positions in two XRD spectra are same with variation in the intensity, we consider the structure to be same. The rest depends on the nature of material i.e its crystallinity and texture.
If peak positions in two XRD spectra are same with variation in the intensity, we consider the structure to be same. The rest depends on the nature of material i.e its crystallinity and texture.
The compounds would be regarded as the same.
The changes in peak intensity could be from reduced crystallinity (in where all peaks would be reduced), or prefer orientation (if there is a change in one or two peaks).
The two highest peaks are in different position, but how close these two peaks? if they are visibly in two position, they could be two different compounds. but if two highest peaks near to each other, they might be the same.
It is an interesting question and the correct answer depends on how different are the intensities. There are structures which their diffraction patterns are very similar. It must be remembered that the diffraction pattern of a substance depends of how the crystallographic sites are occupied by atoms. In the case of multiatoms compounds it is possible that a crystollagraphic site is shared wich gives place to a variation of the intensity for a given structure. Also, for ordered structured, the intensity is a function of the degree of ordering i.e. some disorder change the intensity of the peaks.
Best regards
Pedro
I am not sure if your sample has preferred orientation or not.
Usually the structural change under different thermodynamical conditions such as pressure, temperature and chemical composition is determined by appearance (towards lower symmetry) or disappearnce (towards higher symmetry) of peaks. But this is not a thumb rule. Very recently, I carried out synchrotron high pressure XRD of an oxide based system. I found that there is a systematic intensity excahange of peaks (two doublets) at high pressure, I thought that there is no structural transition. However, Raman study showed a very clear structural transition. Sometimes, if there is a small symmetry change which may not affect the Bragg positions (lattice parameters), but it affects the symmetry.
We mainly Concentrate to the Bragg diffraction peak positions (2 theta). The intensity might be change, it depends on the material quality and composition.
Thank you very much to all of you for your very important information.
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