The only other method that I’m familiar with is the use of calibration standards. Concentrations are obtained from a calibration line previously created from a set of standard samples of known compositions. Based on the intensity or area of a peak per phase, amorphous compounds can be quantified in this way. However, it can depend on your sample and whether you know what phases should be present or not. Best of luck!
Diego Santiago I will add that it is very easy to do the Rietveld refinement. I am using the GSAS, an open-source Python-based software for calculating the phase fraction (wt. fraction). Some of my tutorials may help you do these calculations. One of my such tutorials in which I have refined a sample with two phases is at https://youtu.be/Z_aWz7Tx0Pw. Thanks