Effect of a bias field on the dielectric properties of 0.69Pb(Mg_1/3Nb_2/3)O₃–0.31PbTiO₃ single crystals with different orientations

The microdomain–macrodomain transformations and phase transitions in 0.69Pb(Mg_1/3Nb_2/3)O₃–0.31PbTiO₃ single crystals were investigated by measuring the temperature dependence of relative permittivity as a function of crystal orientation and applied dc bias. A rhombohedral–tetragonal phase transition in the original crystal has been confirmed by powder x-ray diffraction at temperatures from 25 to 180 °C. The results show that microdomain relaxor ferroelectric states in the original crystals could be transformed to macrodomain ferroelectric states by applying a dc bias along any of the , and directions. It is also proposed that an electric field applied along the or direction could induce an orthorhombic or a monoclinic ferroelectric phase, respectively, between the rhombohedral and tetragonal ferroelectric phases in an intermediate temperature range.