Neutron spin echo studies on slow lattice dynamics in relaxor ferroelectrics

The study of slow lattice dynamics using neutron spin echo technique on relaxor ferroelectrics is reviewed. At much higher temperature than TC, we observed oscillating normalized intermediate scattering functions I(Q,t)/I(Q,0) for the [1-10] direction, which is ascribed to low frequency vibrational mode with ω - 40 μeV. Such low frequency vibrational mode suggests that flat energy surfaces exist in the free energy potential along the [1-10] direction, which could be associated with giant dielectric susceptibility in relaxor ferroelectrics near morphotoropic phase boundary. (author)