Microstructure and Piezoelectric Properties of ZnO-added (Na_0.5K_0.5)NbO₃ Ceramics

Abstract

The orthorhombic structure of (Na 0.5 K 0.5 )NbO 3 (NKN) ceramics was maintained when ZnO was added. NKN ceramics have a porous microstructure and dissolve when they are exposed to water. However, as ZnO was added, a dense microstructure was developed and deliquescence was not observed. The mechanical quality factor ( Q m ) and coercive field ( E c ) increased with the addition of ZnO, indicating that ZnO acted as a hardener in the NKN ceramics. The dielectric constant ( ε T 3 / ε o ), piezoelectric constant ( d 33 ) and electromechanical coupling factor ( k p ) increased when a small amount of ZnO was added, which might be due to the increase in density. The good dielectric and piezoelectric properties of ε T 3 / ε o = 500, d 33 = 121 and k p =0.4 were obtained for the NKN ceramics with 1.0 mol% ZnO.