Crossover from diffuse to sharp phase transition by electric field in 0.955Pb(Zn_1/3Nb_2/3)O₃-0.045PbTiO₃

Effect of an electric field along [100] direction on diffuse phase transitions in a relaxor ferroelectric 0.955Pb(Zn_1/3Nb_2/3)O₃-0.045PbTiO₃ (PZN-0.045PT) crystal is studied through dielectric properties and a longitudinal acoustic (LA) phonon. Compared with the diffuse phase transition observed in zero-field cooling in PZN-0.045PT, it shows two sharp phase transitions under field cooling. This result indicates that inhomogeneity is reduced by the electric field in the way that electric field grows the static polar nanoregions and microdomains into larger ferroelectric domains. From a thermodynamic point of view, the electric field enhances the relaxation from the nonequilibrium polymorphic states to the equilibrium homogeneous state. At the same time, ferroelectric tetragonal phase is stabilized with increasing an electric field along [100]