Load Characteristics Of Lead-Free Ceramic Multilayer Actuators Based On Bismuth-Sodium-Titanate

The electromechanical behavior of a lead-free ceramic multilayer actuator is described. The actuator is made of an Nd-doped [Bi0.500Na0.335K0.125Li0.040]TiO3 ceramic with inner electrodes of an Ag/Pd-alloy. For electromechanical characterization, the actuator is under constant mechanical stress, and the strain over the applied electric field is recorded. The mechanical stress ranges from 0.1 to 80MPa. The maximum applied electric field is 8kV/mm. Starting with 0.1MPa mechanical stress, the actuator exhibits a maximum strain of <0.1%. With increasing stress, the strain increases up to 0.17% at 5MPa. With higher stress, the strain decreases and reaches 0.125% at 80MPa. Reducing the mechanical stress leads to a steady increase in strain, which results in a doubling of the strain at 0.1MPa compared with the initial value. The strain characteristic contains an electrostrictive part, a linear piezoelectric regime, and some creep behavior.