Nonlinear behavior of ferroelectric ceramics during mechanical depolarization at room and high temperatures: Experiment and prediction by an experimental formula

The strain changes during temperature rise in a poled lead titanate zirconate rectangular parallelepiped specimen switched by compressive stress at room temperature are measured using an invar-specimen. Firstorder differential equations were derived by analyzing the observed polarization and strain data and solved to give an experimental formula for remnant polarization and remnant strain changes during temperature rise. Then the dependence of pyroelectric and thermal expansion coefficients on remnant state variables and the relations between reference remnant state variables were obtained through experiments. Using the relations and the experimental formula, the strain behavior during mechanical depolarization at a high temperature was predicted from a polarization behavior at the same temperature. It was found that the predictions compared favorably with the measured behavior.