Structure and electrical properties of lead-free (Bi_(0.5)Na_(0.5))TiO_3-Ba(Sn,Ti)O_3 ceramics

摘要

Extending the investigations on (Bi_(0.5)Na_(0.5))TiO_3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Bi_(0.5)Na_(0.5))TiO_3-Ba(Sn,Ti)O_3. X-ray diffraction analysis revealed that, during sintering, all of the Ba(Sn,Ti)O_3 diffuses into the lattice of (Bi_(0.5)Na_(0.5))TiO_3 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(Sn_(0.06)Ti_(0.94))O_3 exhibit relatively good physical and electric properties. For 0.98(Bi_(0.5)Na_(0.5))TiO_3-0.02Ba(Sn_(0.06)Ti_(0.94))O_3 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 1100°C for 3 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 3.56. For 0.98(Bi_(0.5)Na_(0.5))TiO_3-0.02 Ba(Sn_(0.06)Ti_(0.94))O_3 ceramics, the relative density and the thickness coupling coefficient kt reach 98.1% and 0.58, respectively, at the sintering of 1100°C for 5 h. With suitable Ba(Sn_xTi_(1-x))O_3 concentration and sintering condition, a dense microstructure and good electrical properties were obtained.