Good temperature stability of K0.5Na0.5NbO3 based lead-free ceramics and their applications in buzzers

(K0.5-x Li-x)Na-0.5(Nb1-ySby)O-3 (KLNNSx-y, x = 0-4 mol% and y = 0-8 mol%) lead-free piezoelectric ceramics were prepared by the conventional mixed oxide method. The denser microstructure and better electrical properties of the ceramics were obtained its compared to the pure K0.5Na0.5NbO3 ceramic. The temperature stability of the electrical properties of the ceramics was also investigated. The experimental results show that the KLNNS2.5-5 ceramic exhibits good electrical properties (kp similar to 49%, k(31) similar to 30% and epsilon(T)(33)/epsilon(0) similar to 543, tan delta similar to 0.019), and possesses good temperature stability in the temperature range of -40 to 85 degrees C. The related mechanisms for improved electrical properties and temperature stability were also discussed. Moreover. buzzers based on the KLNNS2.5-5 ceramic have been fabricated and their characterization is presented. These results show that the KLNNS2.5-5 ceramic is a promising lead-free material for practical application in buzzers. (c) 2008 Published by Elsevier Ltd.