Lattice dynamics of ferroelectric PbTiO3 by inelastic neutron scattering

Room-temperature dispersion relations of the phonon modes associated with lead ion vibrations in ferroelectric PbTiO3 single crystal have been investigated using inelastic neutron scattering. Both transverse acoustic and transverse optic modes propagating in the direction perpendicular to the spontaneous polarization show considerable splitting due to tetragonal anisotropy. The results of an earlier inelastic neutron scattering study are revised, and it is shown that the present picture is compatible with recent results obtained from Raman and Brillouin spectroscopy.