Investigation of a new lead-free Bi(0.5)(Na(0.40)K(0.10))TiO(3)-(Ba(0.7)Sr(0.3))TiO(3 )piezoelectric ceramic

Lead-free piezoelectric compositions of the (1-x)Bi(0.5)(Na(0.40)K(0.10))TiO(3)-x(Ba(0.7)Sr(0.3))TiO(3 )system (when x = 0, 0.05, 0.10, 0.15, and 0.20) were fabricated using a solid-state mixed oxide method and sintered between 1,050°C and 1,175°C for 2 h. The effect of (Ba(0.7)Sr(0.3))TiO(3 )[BST] content on phase, microstructure, and electrical properties was investigated. The optimum sintering temperature was 1,125°C at which all compositions had densities of at least 98% of their theoretical values. X-ray diffraction patterns that showed tetragonality were increased with the increasing BST. Scanning electron micrographs showed a slight reduction of grain size when BST was added. The addition of BST was also found to improve the dielectric and piezoelectric properties of the BNKT ceramic. A large room-temperature dielectric constant, ε(r )(1,609), and piezoelectric coefficient, d(33 )(214 pC/N), were obtained at an optimal composition of x = 0.10.