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

Ternary lead-free (0.86-x)Bi0.5Na0.5TiO3-0.14Bi(0.5)K(0.5)TiO(3)-xBaZrO(3) 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 similar to 95%. The x-ray diffraction patterns of the (0.86-x)Bi0.5Na0.5TiO3-0.14Bi(0.5)K(0.5)TiO(3)-xBaZrO(3) 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)Bi0.5Na0.5TiO3-0.14Bi(0.5)K(0.5)TiO(3)-xBaZrO(3) piezoelectric ceramics. The highest piezoelectric sensor coefficient d(33) is observed in the x = 0.01 piezoelectric ceramic, whereas the highest piezoelectric actuator coefficient d(33)* is found in the x = 0.03 piezoelectric ceramic. Especially, the x = 0.03 piezoelectric ceramic shows a high d(33)* of 645 pm/V with a small d(33)* variation of similar to 20% in the temperature range of 25-100 degrees C. The investigated (0.86-x)Bi0.5Na0.5TiO3-0.14Bi(0.5)K(0.5)TiO(3)-xBaZrO(3) piezoelectric ceramics have a great potential for the thermal stability lead-free piezoelectric actuator applications.