Lead Free Multilayer Piezoelectric Actuators by Economically New Approach

The replacement of lead zirconate titanate ceramics (PZTs), with a lead-oxide (PbO)-free alternative is the subject of intense investigation worldwide. In this research, a cheap reliable methodology for the fabrication of multilayers (MLs) of lead-free potassium sodium niobate (KNN)-based ceramics is presented without the need for vacuuming and/or hot isostatic pressing of the tape. The thickness per active layer was 193 μm and 102 μm for the 10 and 16 layer MLs actuators, respectively. Effective d₃₃ (piezoelectric coefficient), effective d₃₃^∗ (electrostrain coefficient), bi-polar strain (S_max), max displacement, dielectric constant (ϵ_r) and loss (tanδ) are 2500 pC/N, 4604 pm/V, 0.17%, 2.2 μm, 1812 and 2% at 1 kHz, respectively, where the effective d₃₃ or d₃₃^∗ is the total output of all layers together. The ultimate target materials for potential substitution with KNN-based ceramics and MLs are commercial PZT-4 and PZT-8.