[en] Highlights: • Raman spectroscopy was used for studying the phase composition of thin PZT films. • Principal component analysis was applied to mixed phase PZT Raman spectra. • To define the phase content, a narrowed spectral range in the Raman spectra was used. • Spectral range selection was done by using biplots to represent the Raman spectra. • The quality of diagnostics of thin PZT films was significantly improved. The phase composition of thin lead zirconate titanate (PZT) films was studied under conditions of overlapping Raman spectra of the perovskite, pyrochlore, and substrate phases. Particular attention in the work is given to finding the spectral range according to which an analysis should be carried out. For this purpose, we used the representation of the original multidimensional data by means of biplots (dual graphs). Based on the results of the study, the content of perovskite and pyrochlore phases in growing PZT films was found.