Electromechanical Characterization of Bi-based Lead Free Ceramic Multilayer Actuators

The electromechanical behaviour of a lead-free ceramic multilayer actuator is described. The actuator is made of a Nd-doped bismuth-alkali-titanate ceramic with inner electrodes of an Ag/Pd-alloy. For electromechanical characterization the actuator is under constant mechanical load and the strain over the applied electric field is recorded. The mechanical load ranges from 0.1 to 80 MPa. The maximum applied electric field is 8 kV/mm. Starting with 0.1 MPa mechanical load the actuator exhibits a maximum strain of less than 0.1%. With increasing load the strain increases up to 0.17 % at 5 MPa. With higher load the strain decreases and reaches 0.125% at 80 MPa. Reducing the mechanical load leads to a steady increase in strain, which results in a doubling of the strain at 0.1 MPa compared to the initial value. The strain characteristic contains an electrostrictive part, a linear piezoelectric regime as well as some creep behaviour.