Effect of Bi_2O_3 Addition on the Electrical and Physical Properties of Lead-Free 0.98(Na_(0.5)K_(0.5))NbO_3-0.02 Ba(Zr_(0.04)Ti_(0.96))O_3 Piezoelectric Ceramics

摘要

The 0.98(Na_(0.5)K_(0.5))NbO_3-0.02Ba(Zr_(0.04)Ti_(0.96))O_3 ceramics have been prepared following the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the Ba(Zr_(0.04)Ti_(0.96))O_3 diffuses into the lattice of (Na_(0.5)K_(0.5))NbO_3 to form a solid solution, in which a orthorhombic phase with a perovskite structure was found In order to improve the sinterability of the ceramics, Bi_2O_3 additions were used as a sintering aid. The electromechanical coupling coefficients of the planar mode k_p and the thickness mode k_t reach 0.3 and 0.55, respectively, at the sintering of 1100℃ for 5 h. For 0.98NKN-0.02BZT ceramics by doping 0.5 wt.% Bi_2O_3, the electromechanical coupling coefficients of the planar mode k_p and the thickness mode k_t reach 0.21 and 0.57, respectively. The ratio of thickness coupling coefficient to planar coupling coefficient is 2.7.