Piezoelectric properties of Li- and Ta-modified (K0.5Na0.5)NbO3 ceramics

Lead-free, potassium sodium niobate piezoelectric ceramics substituted with lithium (K0.5−x∕2,Na0.5−x∕2,Lix)NbO3 or lithium and tantalum (K0.5−x∕2,Na0.5−x∕2,Lix)(Nb1−y,Tay)O3 have been synthesized by traditional solid state sintering. The compositions chosen are among those recently reported to show high piezoelectric properties [Y. Saito, H. Takao, T. Tani, T. Nonoyama, K. Takatori, T. Homma, T. Nagaya, and M. Nakamura, Nature (London) 42, 84 (2004); Y. Guo, K. Kakimoto, and H. Ohsato, Appl. Phys. Lett. 85, 4121 (2004); Mater. Lett. 59, 241 (2005)]. We show that high densities and piezoelectric properties can be obtained for all compositions by pressureless sintering in air, without cold isostatic pressing,…