Domain-Related Phase Transitionlike Behavior in Lead Zinc Niobate Relaxor Ferroelectric Single Crystals

The relaxor ferroelectric lead zinc niobate (Pb(Zn_1/3Nb_2/3)O₃) has been intensively investigated, because of its large dielectric and piezoelectric properties for applications in actuators and transducers. In this study, the in-situ behavior of the domains in Pb(Zn_1/3Nb_2/3)O₃ single crystals has been observed using optical microscopy in combination with a charge-coupled device (CCD) camera. The temperature of the sample has been cycled between ?185°C and ?200°C, while applying an electric field of up to ±10 kV/cm. Many characteristics, such as the induction of birefringence, the transition between the microdomains and macrodomains, and the "freeze-in" of the macrodomains, have been optically observed. The optical and dielectric data have been collected and plotted as a function of temperature and electric field. An electric-fieldtemperature diagram showing five domain-related regions has been proposed. The microdomain-to-macrodomain phase transitionlike behavior seems to be an analog of a martensitic phase transition.