ABSTRACT This paper investigates the effect of K1.94Zn1.06Ta5.19O15 (KZT) addition on the sintering behavior and piezoelectric properties in lead-free piezoelectric ceramics of (K0.5Na0.5)NbO3 (KNN). The apparent density of sintered KNN ceramics was increased with KZT addition, and a relative density of above 96.3% was obtained with the doping of over 0.5 mol% KZT. The maximum dielectric and piezoelectric properties of εT3/ε0 = 590, d33 = 126 pC/N, kp = 0.42, and Pr = 18 μC/cm2 were obtained from 0.5 mol% KZT-doped KNN ceramics. A small amount of KZT (∼0.5 mol%) was effective for improving the sintering behavior and piezoelectric properties, but KZT addition exceeding 1.0 mol% was effective only for densification. A small amount of KZT was effective for densification of KNN ceramics by promoting K5.75Nb10.8O30 liquid phase formation. However, even though KNN with 1.0∼2.0 mol% KZT had a relative density of >98.5%, the piezoelectric properties were inferior to those of 0.5 mol% KZT-doped KNN, presumably due to the smaller grain size and excess liquid phase of the KNN ceramics doped with higher amounts of KZT. It is believed that a small amount of KZT could be one of the suitable sintering aids to obtain highly dense KNN based piezoelectric.
Digital Object Identifier 10.1109/TUFFC.2007.569
© 2007, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.