SPONTANEOUS MICRO-MACRO FERROELECTRIC DOMAIN SWITCHING IN PBZRO3-DOPED PB(NI1 3NB2/3)O-3-PBTIO3 SYSTEM/

The possibility of the existence of a spontaneous relaxer-normal ferro electric transition was proposed and examined using 1-3 mol% PbZrO3-do ped Pb(Ni1/3Nb2/3)O-3-PbTiO3 (PNN-PT) systems having tetragonal symmet ry at room temperature. On cooling, the system with 60 mol% Pb(Ni1/3NT b2/3)O-3 underwent a spontaneous transition from a relaxer to a normal ferroelectric state. A microscopic examination demonstrated that the relaxer-normal ferroelectric transition corresponds to a micro-macro d omain switching. Long-range ferroelectric domains below the transition temperature were characterized by twinlike 90 degrees macrodomains wi th tetragonal symmetry. The relaxer-normal transition was further corr elated with the rhombohedral-tetragonal first-order phase transition.