Low-sintering PZT-ceramics for advanced actuators

Much effort has been made to reduce sintering temperature T/sub 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/sub s/ of soft-PZT down to 780/spl deg/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 /spl mu/m) on alumina, showing high remanent polarization (20 /spl mu/C/cm/sup 2/) 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/sub c/ likewise. Nevertheless, a special modification has been found giving a hard-PZT (i.e. T/sub c/=350/spl deg/C) that densifies already at T/sub s/=1050/spl deg/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.