Optical observation of heterophase and domain structures in relaxor ferroelectrics Pb(Zn1/3Nb2/3)O3/9%PbTiO3

Phase boundary and domain structure in relaxer ferroelectrics Pb(Zn1/3Nb2/3)O-3/9%PbTiO3 were observed using a (111) plate under a polarization microscope. The dielectric constant was measured simultaneously to determine exact transition temperatures and to connect the dielectric behavior with phase boundary movements. Movement of the phase boundary between cubic and tetragonal phases was observed at the temperature T-c where the dielectric constant changed abruptly. Below T-c, tetragonal and rhombohedral phases coexisted over a wide temperature range. The complicated domain/phase patterns are classified into two blocks according to extinction position. The difference in extinction positions between the two blocks deviated from 30 degrees and manifested temperature dependence. This fact indicates that the symmetry-lowering occurs in the heterophase. A small, but the distinct temperature hysteresis of the dielectric constant was related to the nucleation and growth of one phase into another phase.