Structure and Electrical Properties of Lead-Free (Bi<sub>0.5</sub>Na<sub>0.5</sub>)TiO<sub>3</sub>-Ba(Sn,Ti)O<sub>3</sub> Ceramics

Abstract

Extending the investigations on (Bi0.5Na0.5)TiO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Bi0.5Na0.5)TiO3-Ba(Sn,Ti)O3. X-ray diffraction analysis revealed that, during sintering, all of the Ba(Sn,Ti)O3 diffuses into the lattice of (Bi0.5Na0.5)TiO3 to form a solid solution, in which a rhombohedral phase with a perovskite structure was found. It was found that the samples with a low content of Ba(Sn0.06Ti0.94)O3 exhibit relatively good physical and electric properties. For 0.98(Bi0.5Na0.5)TiO3-0.02Ba(Sn0.06Ti0.94)O3 ceramics, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.16 and 0.57, respectively, at the sintering of 1100oC for 3 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 3.56. For 0.98(Bi0.5Na0.5)TiO3-0.02Ba(Sn0.06Ti0.94)O3 ceramics, the relative density and the thickness coupling coefficient kt reach 98.1% and 0.58, respectively, at the sintering of 1100oC for 5 h. With suitable Ba(SnxTi1-x)O3 concentration and sintering condition, a dense microstructure and good electrical properties were obtained.