XRD data were processed in order to extract the phase composition of each powder sample. Following initial background correction using the ZBH, the sample crystallinity was evaluated (see Figure ). For this, a numerical frequency analysis of the XRD pattern was conducted using Fourier transformation: the XRD pattern of a crystalline material comprises of sharper peaks with higher spatial frequency, whereas amorphous fractions generate a diffraction pattern with lower frequency, smooth humps. Based on this difference, noise signals with magnitudes below 1% after Fourier transform are filtered out, corresponding to a cut-off frequency of 0.14 deg -1 . The calculated uncertainty in the estimated amount of the amorphous phase is below 4% for all samples.