Abstract

Electric field induced strain is one of the most important performance parameters for multilayer ferroelectric actuators. In these devices, donor doped morphotropic lead zirconate titanate (PZT) ceramics are the materials currently used. Strain and, more general, electromechanical properties of these piezoceramics are grain size dependent. Any attempts to decrease the sintering temperature will suffer from the drawback, that changing T-s will also change the grain size and therefore the electromechanical properties. A series of NbSr-doped PZT materials with 11 different Zr/Ti ratios over the whole range of the morphotropic phase boundary has been prepared, and sintered at temperatures between 975 and 1100 degrees C. Grain size and x-ray diffraction patterns were evaluated and the strain behavior was measured and analyzed. Qualitative similar effects of grain size on strain behavior were found for all morphotropic PZT 1Nb2Sr compositions: When lowering the sintering temperature, field induced strain decreases whereas the remanent strain increases. Quantitative differences between the materials indicate that, in addition to the influence from the grain size, there are effects specific for the compositions, which are most probably related to changes in phase composition. From the inverse behavior of remanent strain and field induced strain versus grain size, on a macroscopic level, a description of the mechanisms which govern the effects of grain size on strain is derived. [doi:10.1063/1.3294648]