Rhombohedral-to-tetragonal phase transformation and thermal depolarization in relaxor-based ferroelectric single crystal

Abstract

The rhombohedral-to-tetragonal (R-T) transformation in relaxor single crystals occurs over a temperature range, manifested by the coexistence of rhombohedral (R) and tetragonal (T) microscopic and nanotwin domains, a string of thermal current signals, and continued degradation of dielectric and electromechanical properties. Thermal current and high-resolution x-ray diffraction results suggest TRT 100-135 °C for [001]-poled PZN-4.5%PT and 90-115 °C for [001]-poled PZN-7%PT. The " TRT " determined from the dielectric permittivity-temperature plot of poled crystals corresponds to the lower bound of TRT, which is also a good indication of the depolarization temperature (TDP) of relaxor ferroelectric single crystals above which perceptible property degradation begins. © 2008 American Institute of Physics.