Dynamics of lattices in solids. Lattice dynamics in relaxor ferroelectrics studied by inelastic neutron scattering

From inelastic neutron scattering studies on a single crystal of relaxor ferroelectric 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3, we have clarified that flipping motion of electric dipoles (relaxation) in polar nano regions (PNRs) are coupled with lattice vibrations (phonon) in surrounding regions. Through the mode-coupling between phonon and relaxation modes, we have clarified that the diffusive phase transition in relaxors is governed by relaxation modes in PNRs which show critical slowing down in a wide temperature range as the size of PNR increases. In addition, we revealed a novel low-frequency vibration mode using neutron spin-echo technique, which could be origin of giant response in relaxors near Morphotropic Phase Boundary. (author)