Effect of Ta2O5 Addition on the Electrical and Physical Properties of Lead-Free 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3 Piezoelectric Ceramics

In this paper, the effects of Ta2O5 addition on the electrical and physical properties of 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3 were investigated. The 0.98(Na0.5K0.5)NbO3 -0.02(Na0.5Bi0.5)TiO3 [0.98NKN-0.02NBT] ceramics with the addition of 0 similar to 0.5 wt% Ta2O5 have been prepared following the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the (Na0.5Bi0.5)TiO3 diffuse into the lattice of (Na0.5K0.5)NbO3 to form a solid solution, in which a orthorhombic phase with a perovskite structure was found. For 0.98NKN-0.02NBT ceramics by doping 0.1 wt% Ta2O5, the poled dielectric constant (K-33(T)) is 1090. The electromechanical coupling coefficients of the planar mode k(p) and the thickness mode k(t) reach 0.39 and 0.48, respectively. Our results show that 0.98NKN-0.02NBT with the addition of 0.1 wt% Ta2O5 is a good lead-free piezoelectric ceramic.