IMF2017

0.96(K_0.48Na_0.52)_{1 + x}Nb_0.93Sb_0.02Ta_0.05O₃-0.04Bi_0.5(K_0.12Na_0.88)_0.5ZrO₃ [(KN)_xNTS-BKNZ] lead-free piezoelectric ceramics were prepared by conventional solid-state reaction method. The effects of excessive alkali metals on the sintering character, phase structure, dielectric, piezoelectric, and ferroelectric properties were systematically explored. The sintering temperature of (KN)_xNTS-BKNZ ceramics gradually increases and the sintering temperature zone becomes narrow with the increasing x value. The coexistence of rhombohedral and tetragonal phases has been found in (KN)_xNTS-BKNZ ceramics when 0 ≤ x ≤ 0.03. When x ≤ 0.03, the ceramics show a continuous increasing of T_R-T, T_C, d₃₃, and εr with the increasing x. The maximal piezoelectric coefficient d₃₃ of 415 pC/N was obtained at x = 0.03. In addition, these ceramics presented a good temperature stability in piezoelectricity. This study exhibits that excessive alkali metals make a great impact on sintering character and electric properties on KNN ceramics. It was believed that this work would be helpful for further enhancing piezoelectric properties in KNN ceramics.