DYNAMICS OF THE FREEZING PROCESS IN RELAXOR FERROELECTRICS

The dynamics of the freezing process in relaxer ferroelectrics are inv estigated by Monte Carlo computer simulation. The concepts of ''frozen dipole'' and ''slow dipole'' are proposed according to the flipping f requency during the observation' time of simulation. The deviation fro m Curie-Weiss behavior and the frequency dispersion in relaxor ferroel ectrics have been proved to be caused by the increasing proportion of slow dipoles. The simulation shows that the external field reduces the dielectric constant and increases the temperature of dielectric maxim um, which agrees with the experiment results. The polarization behavio r with various electrical and thermal histories and starting from diff erent initial states is also simulated and a systematic explanation ba sed on the bifurcation tree of components in phase space is given. It is proposed that the relaxer characteristics are caused by a gradual f reezing process of polar microregions, which arises from the inhomogen eous crystal structure of this kind of material.