X-ray diffraction can also be used to determine
the degree of crystallinity
of a solid. To do this you need a graph on which the angle of diffraction is on the horizontal axis
and the intensity on the vertical
When a diffraction graph is made of an amorphous solid, there will be no peaks in the graph (since there is no lattice to produce interference). However, the material will still scatter the radiation and the result will be a smooth halo of scattered radiation in the graph.
A material that is partly amorphous and partly crystalline will produce a graph that consists of the amorphous halo with peaks superimposed.
To determine the fractions of both phases, you can determine the relative intensity of the halo and the peaks by calculating the surface area under the peaks and under the halo, and then calculating the ratio.
For quantitative determinations you'll also need samples of which you already know the degree of crystallinity (preferably a completely amorphous and a completely crystalline sample), for calibration.