Determination of crystallinity can be a fraught subject, because it is
usually assumed in such measurements that the background is from
amorphous material while the sharp peaks are from crystalline material.
So the standard way to do this would be to have a method for extracting
the background and then comparing the total area of the background with
the total area under the peaks. However, the background need not arise
solely from  amorphous material but from several other sources, such as
short range order diffuse scattering, air scattering, scattering from
slits etc etc. Furthermore, determinign the total area under the
background needs some care as one needs to know where it begins and
where it ends. 

The literature on crystallinity usually talks about 1 and 2 state
models. A 2 state model is one which one has a mixture of crystals and
amorphous material, and if one believes that this is what you have in
your sample then the percentage crystallinity can be derived from the
comparison of peaks to background, as mentioned above. A 1-state model
is where one has crystalline materials with sufficient breakdown in
long-range order to give a background due to diffuse scattering.


Mike Glazer


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