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

The effect of prestress on the nonlinear dielectric (polarization) and piez oelectric (strain) response of lead zirconate-lead titanate (PZT-5H) piezoe lectric ceramic is studied. The response to bipolar (-2/+2 MV/m) and unipol ar (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 mai nly influences the first non-180 degrees process. In the unipolar regime, t he 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 mot ion. Based on rule of mixtures formulation, an analytical model is develope d to estimate the optimum prestress value for the unipolar electric loading condition. It is found that the dielectric and piezoelectric response of t he material is proportional to the volume fraction of the non-180 degrees d omains and the difference in domain wall pressure created by mechanical and electrical loads. (C) 2001 American Institute of Physics.