Effect of BaZrO3 Depant on the Structure and Electric Properties of (K0.49Na0.51)0.98Li0.02(Nb0.77Ta0.18Sb0.05)O3 Lead-free Piezoceramics

(K0.49Na0.55)(0.98)Li-0.02(Nb0.77Ta0.18Sb0.05)O-3-xBaZrO(3) (NKNLST-xBZ, x = 0-0.020 mol) lead-free piezoelectric ceramics were prepared by solid state reaction method. The effect of BaZrO3 doping amount on the piezoelectric, dielectric, electromechanical and ferroelectric properties were investigated systematically. The results revealed that the crystal structures transformed from orthorhombic phase to tetragonal phase with BaZrO3 doping amount increasing, and the coexistence of orthorhombic-tetragonal phases were observed in the x range from 0.005 to 0.008. Under the condition of two phases co-existence, the ceramic grain became small and uniform and dielectric loss tan delta significantly decreased, while the piezoelectric constant d(33) and planar electro-mechanical coupling factor k(p) increased. The dielectric constant epsilon(T)(33)/epsilon(0) of this system ceramics increased continuously with the increase of the BaZrO3 doping amount and the phase transition temperatures shifted to lower temperature. The optimized piezoelectric properties could be obtained at the x = 0.005 composition ceramic as follows: the mized piezoelectric properties could be obtained at the x = 0.005 composition ceramic as follows: the piezoelectric constant d(33) = 372 pC/N, planar electromechanical coupling coefficient k(p) = 47.2%, dielectric loss tan delta = 3.1%, a high dielectric constant epsilon(T)(33)/epsilon(0) = 1470 and Curie temperature T-c = 208 degrees C.