Dielectric response of ferroelectric relaxors

The real and imaginary parts of dielectric permittivities of a ferroelectri c relaxer are studied by the Monte Carlo (MC) simulation as a function of f requency and temperature. The simulation results are analyzed by the fluctu ation-dissipation theory (FDT). In contrast to the previous results (Appl. Phys. Lett, 69 (1996) 2353), the imaginary part of permittivity qualitative ly agrees with the experimental results very well. The measuring frequency and T-pi, the temperature at which the imaginary part of dielectric permitt ivity reaches its maximum, follow the Vogel-Fulcher relationship. The l/f t ype of noise is also found, which implies a glassy phase at low temperature . We suggest that the dipolar glass model can explain the observed non-Deby e relaxation and non-Arrhenius temperature dependence of the relaxation tim e. The conduction loss assumption is not necessary for explaining the imagi nary part of dielectric permittivity behaviors. (C) 2000 Elsevier Science L td. All rights reserved.