Effects of nano-sized BiFeO3 addition on the properties of high piezoelectric response (1 − x)Bi0.5Na0.5TiO3–xBi0.5K0.5TiO3 ceramics

The role of BiFeO3 addition on the crystal structure, microstructure, and the electrical and electromechanical properties of high-sensitivity Bi0.5Na0.5TiO3–Bi0.5K0.5TiO3 ferroelectric ceramics for compositions at the morphotropic phase boundary (MPB) is investigated. A perovskite solid solution from nano-sized BiFeO3 and Bi0.5Na0.5TiO3–Bi0.5K0.5TiO3 powders is obtained, in which the persistence of a MPB in the ternary system is demonstrated. The structural characterization, along with the electrical properties, indicates the stabilization of intermediate domain configurations, associated with a decrease of the temperature for the development of the ferroelectric long-range order. As a consequence, high phase-change electromechanical response is found for certain small BiFeO3 additions. This result is very promising for the processing of textured ceramics taking advantage of the decomposition behaviour of BiFeO3. Ceramic texturing is demonstrated, a key technology for developing lead-free piezoelectrics that can replace Pb(Zr,Ti)O3.