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 BiFeO 3 addition on the crystal structure, microstructure, and the electrical and electromechanical properties of high-sensitivity Bi 0.5 Na 0.5 TiO 3 –Bi 0.5 K 0.5 TiO 3 ferroelectric ceramics for compositions at the morphotropic phase boundary (MPB) is investigated. A perovskite solid solution from nano-sized BiFeO 3 and Bi 0.5 Na 0.5 TiO 3 –Bi 0.5 K 0.5 TiO 3 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 BiFeO 3 additions. This result is very promising for the processing of textured ceramics taking advantage of the decomposition behaviour of BiFeO 3 . Ceramic texturing is demonstrated, a key technology for developing lead-free piezoelectrics that can replace Pb(Zr,Ti)O 3 .