COMPOSITIONAL HETEROGENEITY AND THE ORIGINS OF THE MULTICELL CUBIC STATE IN SN-DOPED LEAD-ZIRCONATE-TITANATE CERAMICS

A systematic study of Sn-doped lead zirconate titanate ceramics has been carried out as a function of Sn and Ti contents. Dielectric constant and remanent polarization measurements have been performed and compared to our recent transmission electron microscopy study. The dielectric maximum was found to be associated with a multicell cubic state, rather than a macroscopic transformation into an antiferroelectric state. In addition, a strong deviation from Curie-Weiss behavior was observed for temperatures several hundred degrees above the permittivity maximum. Evidence is presented that the dielectric maximum is associated with a metastable locking of the incommensuration, rather than a phase transformation. Under application of an electric field, the metastability is seemingly overridden, and a tripling of the dielectric constant is observed. The strong enhancement of the dielectric softening is believed to arise due to a modulation of the phase on the incommensurate structure by the electric field.