IMF2017

To develop high-performance piezo-/ferroelectric materials and to understand their underlying physical and chemical mechanisms, a novel ternary solid solution has been synthesized by solid state reaction method in the form of ceramics with compositions across the morphotropic phase boundary (MPB). This ternary system is formed by incorporating Bi-based complex perovskite Bi(Zn_2/3Nb_1/3)O₃ (BZN) into the relaxor-based binary solid solution of Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT). X-ray diffraction analysis indicates that the (0.95-x)PMN-0.05BZN-xPT solid solution transforms from a rhombohedral phase to a tetragonal phase when the composition is varied across the MPB which is located at x ~ 0.30 to 0.33. Enhanced relaxor behavior is found in this system and the relaxor state transforms to a ferroelectric phase spontaneously upon cooling, or under application of an electric field. The incorporation of BZN into PMN-PT results in the suppression of the MPB-related depoling (at T_RT) and a significant enhancement of piezoelectric and ferroelectric properties compared with those of PMN-PT binary ceramics. This enhancement of properties is attributed to the beneficial effects of BZN which enhances the structural distortion due to the lone-pair electrons on Bi³⁺ and the ferroelectrically active Zn²⁺ and Nb⁵⁺, and to the enhanced relaxor behavior arising from the increase of the local disorder and nanodomains effect. With its strengthened properties, the (0.95-x)PMN-0.05BZN-xPT system becomes a promising electronic ceramic material for such devices as actuators, sensors, capacitors, and transducers for a wide range of applications.