Influence of temperature on the electromechanical and fatigue behavior of piezoelectric ceramics

This paper presents research results on the electro-thermomechanical behavior of piezoelectric ceramics for use in actuator applications with an emphasis on ferroelectric fatigue. The material being investigated is a lead zirconate titanate piezoelectric ceramic with the composition PbZr0.53Ti0.47O3 (PZT-5H). Results presented in this paper include an augmented constitutive model that accounts for the temperature-dependent piezoelectric properties. Using this model, nonlinear effects measured at one temperature can be extrapolated to other temperatures with good accuracy. Experimental studies into 180 degrees and 90 degrees polarization switching of PZT-5H indicate that the dielectric flux to dipole the material appears to be an adequate criterion for predicting this nonlinear switching behavior. Fatigue studies show that material degradation is strongly influenced by temperature and by the magnitude of the applied electric field. Above a critical temperature, PZT-5H no longer fatigues in the presence of large electric fields due to changes in the electromechanical properties such as the depolarization strain. Using a finite element model incorporating the proposed constitutive relations along with a domain switching criterion, this paper suggests that fatigue degradation is primarily caused by mechanical stresses in the material resulting from spatially variant electric fields causing preferential domain wall motion. The large stress mismatches induce mechanical damage in the form of cracks. (C) 1998 American Institute of Physics.