NMR and the spherical random bond-random field model of relaxor ferroelectrics

To determine the nature of the relaxer state and, in particular, to discrim inate between a ferroelectric state broken up into nanodomains under the co nstraint of quenched random fields and a glassy state we have measured the temperature dependences of the nonlinear dielectric susceptibility in zero field as well as the temperature dependence of the local polarization distr ibution function and the Edwards-Anderson order parameter in PMN single cry stal via Nb-93 NMR. The experimental results can be quantitatively describe d by the newly proposed Spherical Random Bond-Random Field model of relaxer ferroelectrics. (C) 1999 Elsevier Science Ltd. All rights reserved.