Thermally-Stable High EFIS Properties of Ternary Lead-Free BNT-BKT-BZ Piezoelectric Ceramics

Abstract

Ternary lead-free (0.86−x)Bi0.5Na0.5TiO3-0.14Bi0.5K0.5TiO3-xBaZrO3 piezoelectric ceramics were successfully fabricated using a conventional solid-state reaction method. The relative densities, crystal structures, dielectric constant, electric field-induced polarization loops, and electric field-induced strain curves of the sintered piezoelectric ceramics were analyzed. All the piezoelectric ceramics were well sintered with a single perovskite structure and a high relative density of ~ 95%. The x-ray diffraction patterns of the (0.86−x)Bi0.5Na0.5TiO3-0.14Bi0.5K0.5TiO3-xBaZrO3 piezoelectric ceramics indicate a rhombohedral-to-tetragonal phase transition as a function of x. The BaZrO3 addition reduces the ferroelectricity and enhances the piezoelectricity of the (0.86−x)Bi0.5Na0.5TiO3-0.14Bi0.5K0.5TiO3-xBaZrO3 piezoelectric ceramics. The highest piezoelectric sensor coefficient d33 is observed in the x = 0.01 piezoelectric ceramic, whereas the highest piezoelectric actuator coefficient d33* is found in the x = 0.03 piezoelectric ceramic. Especially, the x = 0.03 piezoelectric ceramic shows a high d33* of 645 pm/V with a small d33* variation of ~ 20% in the temperature range of 25–100°C. The investigated (0.86−x)Bi0.5Na0.5TiO3-0.14Bi0.5K0.5TiO3-xBaZrO3 piezoelectric ceramics have a great potential for the thermal stability lead-free piezoelectric actuator applications.