Dielectric and piezoelectric response of lead zirconate-lead titanate at high electric and mechanical loads in terms of non-180° domain wall motion

The effect of prestress on the nonlinear dielectric (polarization) and piezoelectric (strain) response of lead zirconate-lead titanate (PZT-5H) piezoelectric ceramic is studied. The response to bipolar (-2/+2 MV/m) and unipolar (0/+2 MV/m, -0.4/+2 MV/m) electric field under constant prestress (up to 175 MPa) is experimentally evaluated. In the bipolar regime, prestress mainly influences the first non-180 degrees process. In the unipolar regime, the dielectric and piezoelectric response achieve maximum values near 50-60 MPa because the prestress increases the number of available non-180 degrees domains. A detailed description of the effect of the prestress on electro-mechanical response is provided in terms of non-180 degrees domain wall motion. Based on rule of mixtures formulation, an analytical model is developed to estimate the optimum prestress value for the unipolar electric loading condition. It is found that the dielectric and piezoelectric response of the material is proportional to the volume fraction of the non-180 degrees domains and the difference in domain wall pressure created by mechanical and electrical loads. (C) 2001 American Institute of Physics.