Quantitative Analysis of Micro-Macro Domain Transition of PNN-PT-PZ(x) System at Higher PZ Content

摘要

Since the discovery of relaxor behavior in Pb(Mg_(1/3) Nb_(2/3) )O_3 (referred to as PMN), the studies of relaxor ferroelectrics with Pb(B′_(1/3)B″_(2/3))O_3 type perovskites have intensified because of their excellent dielectric and electromechanical properties. The present study is mainly focused on the quantitative analysis of micro-macro domain transition, using dielectric spectroscopy, hot-stage TEM. The deviation from Curie-Weiss behavior was investigated over a broad range of temperature. As the relative contents of PbZrO_3 increased, the Curie-Weiss temperature decreased, while the Curie-Weiss constant increased. However, the Lorentz polarization factor (γ) decreased with increasing PbZrO_3 content, indicating an enhanced relaxor behavior in the PNN-PT-PZ(x) system at higher PZ content. A microscopic examination demonstrates that the relaxor-normal ferroelectric transition corresponds to a micro-macro domain switching. The long-range ferroelectric domains below the transition temperature were characterized by twin-like 90° macro domains with tetragonal symmetry and by the subdomains, which presumably relieves the internal electrostrictive strains associated with the polarization nonuniformity caused by the polar nanodomains.