Interpretation of Tm and T* in Relaxor Ferroelectric 0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3

The dielectric property of relaxor ferroelectric 0.93Pb(Zn_1/3Nb_2/3)O₃-0.07PbTiO₃ single crystals (PZN-0.07PT) is studied to investigate the ferroelectric phase transition. The temperature dependence of the susceptibility of the central peak in the light scattering shows a very similar behavior to the real part of the dielectric constant, indicating that the diffuse peak in the temperature dependence of the dielectric constant is induced by relaxation of the polarization. We suggest that the origin of the relaxation above T_m is the non-180° polarization flipping of a small polar nanoregion (PNR). Additionally, the behavior of the PNRs is interpreted through both the Brillouin spectra and high-energy synchrotron-radiation powder diffraction patterns. Our results reveal that T^*~ 499K is the temperature below which the growth rate of the dynamic polarization fluctuation is suppressed by the additional random electric field induced by the generation of the static PNRs.