“…Lattice dynamics of the antiferroelectric and ferroelectric materials of the PZO group were studied both experimentally [ 11 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ] and theoretically [ 26 , 27 , 28 , 29 , 30 ]. In addition to the direct measurements of the phonon spectra using the optical spectroscopy and inelastic X-ray scattering (IXS) complementary diffuse scattering (DS) studies were done [ 14 , 31 , 32 , 33 , 34 ] The main attention was paid to the dynamic origin of the AFE phase and the details of the phonon dispersion around the -point ( ) and the R-point ( ).…”