KNN Based Lead-Free Piezoceramics with Improved Thermal Stability

Lead-free piezoelectric ceramics (1-x)(Na_0.53K_0.404Li_0.066)Nb_0.92Sb_0.08O₃+xSrTiO₃ are fabricated by conventional solid-state sintering method, and their dielectric and piezoelectric characteristics are investigated. With the addition of SrTiO₃, the growth of the grain size is restrained, meanwhile the phase transition temperature of orthorhombic-tetragonal is shifted below room temperature. It is found that the ceramics with x=0.010 exhibit excellent piezoelectric properties (d₃₃=220pC/N, k_p=41%, k_t=39%) and improved thermal stability around room temperature. The results indicate that these materials are promising lead-free piezoceramics for practical operations.