Effects of K _4CuNb _8O _(23) on phase structure and electrical properties of K _(0.5)Na _(0.5)NbO _3-LiSbO _3 lead-free piezoceramics

摘要

Dense K _4CuNb _8O _(23) (KCN) modified 0.948K _(0.5)Na _(0.5)NbO _3-0.052LiSbO _3 (KNNLS) ceramics were prepared by conventional solid state reaction method. The effect of addition of K _4CuNb _8O _(23) liquid phase sintering aid on the phase structure and electrical properties of ceramics was studied. Results showed that K _4CuNb _8O _(23) induced a perovskite structure transition from coexistence of orthorhombic and tetragonal phases to orthorhombic symmetry. The addition of K _4CuNb _8O _(23) promoted the sintering of KNNLS ceramics. In particular, the K _4CuNb _8O _(23) addition to the KNNLS greatly improved the mechanical quality factor Q _m value. The ceramics with x=0.8 sintered at 1090°C possess the optimum properties (Q _m=192, d _(33)=135 pC/N, tan δ=0.024 and k _p=0.357). These results indicate that the ceramic is a promising candidate for lead-free high-power piezoelectric devices, such as piezoelectric actuators, transformers and filter materials.