In XRD, how do you distinguish among the crystallized phase, amorphous phase, and a mixture of the two? How will the peak look like in a mixture of a crystalline and amorphous material?
Hi Williams Owusu Boadi , the amorphous phase has broad diffraction peaks. When it transforms to a crystallized phase, sharp peaks will be observed, and the amorphous broad peaks will decrease from the mixed peaks. cf. open access:
Article Structural Change from Amorphous to Nano Icosahedral Quasicr...
Please take a look at this presentation
http://prism.mit.edu/xray/introduction%20to%20xrpd%20data%20analysis.pdf
As Gyoko mentioned, if you have an amorphous phase in your sample, the xrd diffraction peaks appear as broad bumps. However, since these peaks are not strong they may not be easily observed unless the amorphous phase is high enough. In most cases the amorphous phase can be converted to crystalline phase by heating treatments.
To follow up with what has been said above by colleagues, actually, the broad peak in an amorphous material is caused due to short range order as there is presence of a fixed distance between bonds. The broadness in amorphous could be explained somehow by the rapid decrease of peak height with increasing 2-theta. However, in quartz, which is a crystalline material, rigid long range order is present and this induces to express sharp peaks at fixed Bragg angles relative to each hkl. In a mixture, you will have main crystalline peaks showing up on the broad peak. I enclose a figure with an amorphous signature being on top and a crystalline signature below to explain more what broad and sharp peaks mean in SiO2 example.
https://h-and-m-analytical.com/wp/wp-content/uploads/2015/04/phase_id.pdf
For a crystalline phase you will get sharp powder diffraction pattern while for a amorphous phase it will result as a broad peak. In a mixture of above two type of phases mostly you will not get a good base line. Using match software you can identity your phases and sort-out the problem of baseline.
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