(K,Na)NbO₃-Based Multilayer Piezoelectric Ceramics with Nickel Inner Electrodes

A lead-free (K,Na)NbO 3 -based multilayer piezoelectric ceramic with nickel inner electrodes was obtained. Its normalized electric-field-induced thickness strain ( S max / E max ) was 360 pm/V, where S max denotes the maximum strain and E max denotes the maximum electric field. This value of 360 pm/V is about half that for the Pb(Zr,Ti)O 3 -based ceramics that are widely used. However, the (K,Na)NbO 3 -based multilayer ceramic can achieve comparable displacement to that attainable with Pb(Zr,Ti)O 3 -based multilayer ceramics by stacking more ceramic layers with smaller thicknesses. Additionally, it is easier to reduce the ceramic-layer thickness by using nickel electrodes. The developed (K,Na)NbO 3 -based multilayer ceramic is thus considered a good candidate for lead-free piezoelectric actuators.