Effect of New Phase Boundary on the Dielectric and Piezoelectric Properties of K_0.5Na_0.5NbO₃- xBaZrO₃- yBi_0.5Na_0.5TiO₃Lead-free Ceramics

Abstract

(1-x-y)K_0.5Na_0.5NbO₃- xBaZrO₃- yBi_0.5Na_0.5TiO₃ ceramics (abbreviated as KNN-x, y) were prepared by the conventional solid state reaction method. BaZrO₃ results in the increase of T _R-O, and Bi_0.5Na_0.5TiO₃ leads to the decrease of T _O-T. The ceramics co-modified with these two additives exhibit a new phase boundary. With the shrinkage of O phase in the R–O–T phase structure, the first order O-T phase transition evolved to the secondary order R-T phase transition according to the thermal hysteresis. Enhanced piezoelectric properties (d ₃₃ = 348 pC/N and k _P = 43.2%) were obtained near the new phase boundary when x = 0.04 and y = 0.025.

Keywords:

• Lead-free Piezoelectric Ceramics
• Perovskite
• (K, Na)NbO₃ (KNN)-based Ceramics

Acknowledgments

This work was supported by National Science Foundation of China (NSFC Nos. 51272164, 50772068 and 50972095) and Foundation of Doctor Training Program in University and College in China (Nos. 20030610035, and 20080610020).