Low-Temperature Sintering of (KNa)NbO Piezoelectric Ceramics.

(KNa)NbO piezoelectric ceramics can be sintered at a temperature as low as 750 °C for 5 h by incorporating LiCO + BiO + ZnO as the sintering aid, whereas the conventional sintering temperature is around 1,100 °C. The optimal 'soft' piezoelectric properties are obtained for ceramics sintered at 850 °C for 5 h. The dielectric permittivity ( ε), piezoelectric coefficient ( d), electromechanical coupling ( k) and mechanical quality factors ( Q) of (K, Na)NbO modified with 5.5 wt% sintering aids are 1,436, 90 pC/N, 0.3 and 10, respectively. These values are similar to the values obtained for (KNa)NbO ceramics sintered above 1,100 °C. The underlying mechanism for abrupt change of dielectric permittivity is explained. [ABSTRACT FROM AUTHOR]