Disorder and relaxation mode in the lattice dynamics of the PbMg1/3Nb2/3O3 relaxor ferroelectric

Abstract

The low-energy part of vibration spectrum in PbMg1/3Nb2/3O3 (PMN) relaxor ferroelectric was studied by inelastic neutron scattering. We observed the coexistence of a resolution-limited central peak with strong quasielastic scattering. The line width of the quasielastic component follows a Γ0+Dq2 dependence. We find that Γ0 is temperature dependent. The relaxation time follows the Arrhenius law well. The presence of a relaxation mode associated with quasielastic scattering in PMN indicates that order-disorder behavior plays an important rôle in the dynamics of diffuse phase transitions. © 2004 The American Physical Society.