Ferroelectric-paraelectric phase transition and dielectric relaxation in PMN-PT relaxor ferroelectrics

To observe various relaxation phenomena in the ferroelectric-paraelectric phase transition temperature range, not only low-field dielectric properties but also high-field properties were investigated. Dielectric constants were measured under varing frequencies at the oscillating level of 1.1 volt. Polarizations induced by a bipolar electric field as well as those induced by a unipolar electric field were measured for 0.9Pb(Mg1/3Nb2/3)O-3-0.1PbTiO(3) relaxer ferroelectric ceramics in the phase transition temperature range of -50 similar to 90 degrees C. When fitting with the Vogel-Fulcher relationships, T-f was found to be 294.6 K and a close agreement between experimental data and curve fitting was observed. Thus, dielectric relaxations could be modeled by the Vogel-Fulcher relationships not only with the physical properties such as the dielectric constants but also with the electric-field-induced polarization and the pyroelectric properties.