Material Design of High-Dielectric-Constant and Large-Electromechanical-Coupling-Factor Relaxor-Based Piezoelectric Ceramics

Abstract

Material design to achieve a f high dielectric constant of ε33T/ε0>5,000 and a large planar-mode electromechanical coupling factor (EMCF) of kp>65% near the morphotropic phase boundary (MPB) in the multicomponent system of Pb(Sc1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-Pb(Ni1/3Nb2/3)O3-(Pb,Ba,Sr)(Zr,Ti)O3 (PSN-PMN-PNN-PBSZT) ceramics was investigated. To obtain the MPB composition of the multicomponent system, a smart material design was applied to predict Curie temperature (Tc) and exact TiO2 content in the system. In addition, to realize a high dielectric constant and a large EMCF, a low-mass (LM) B-site ion model and a B-site disordering model in lead perovskite were applied. To enhance disordering of the B-site ions, we focused on the complex perovskite system ceramics PSN-PMN-PNN-PBSZT, which consist of three A-site ions, Pb, Ba and Sr, and six LM B-site ions, those of Sc, Mg, Ni, Nb, Ti and Zr. Dielectric constants of ε33T/ε0=5,500, a planar-mode EMCF of kp=72%, a piezoelectric constant of d33=850 pC/N and Tc=153°C were confirmed in the PSN-PMN-PNN-PBSZT ceramics near the MPB by utilizing the material design procedure.