Low-sintering PZT-ceramics for advanced actuators

Much effort has been made to reduce sintering temperature T_s of PZT powders, driven by the demands of multilayer actuator fabrication. Suppression of PbO-evaporation and usability of cost effective electrode materials have been the main reasons. We succeeded in reducing T_s of soft-PZT down to 780°C by creating liquid phases during sintering. Consequently, the fabrication of components with high surface to volume ratio became possible. For example, dense PZT thick films (thickness 50...150 μm) on alumina, showing high remanent polarization (20 μC/cm²) and high mechanical strength were prepared. In order to raise operation frequency and temperature the development of low-sintering hard-PZT has been investigated. This task turned out to be more difficult, because most eutectic additives tend to reduce Curie temperature T_c likewise. Nevertheless, a special modification has been found giving a hard-PZT (i.e. T_c=350°C) that densifies already at T_s=1050°C/2h. The paper reports on our compositional development of low-sintering PZT-ceramics together with its impact on the design and performance of advanced actuators