EFFECT OF ELECTRIC-FIELD ON NEUTRON-SCATTERING IN LEAD MAGNONIOBATE

The temperature dependence of the intensity of the Bragg and the trans verse component of quasielastic neutron scattering from the single-cry stal model relaxor PbMg1/3Nb2/3O3 has been studied for various applied electric fields. It is shown that application of a field E > E-th app roximate to 1.6 kV/cm increases the elastic scattering intensity and r educes the intensity of the transverse diffuse- scattering component a nd that, below 230 K and for E > 6kV/ cm, the elasticscattering intens ity saturates while the temperature-dependent part of the transverse d iffuse-scattering component becomes practically suppressed. The measur ed temperature and field dependences of the intensity of type (h00) an d (hh0) Bragg reflections provide supportive evidence both for the pre sence of considerable lead-ion displacements relative to the ideal per ovskite sites and for the existence in strong electric fields of an in duced transition to the ferroelectric phase below 250 K. (C) 1998 Amer ican Institute of Physics. [S1063-7834(98)02910-4].