Nonlinear behavior of piezoelectric lead zinc niobate–lead titanate single crystals under ac electric fields and dc bias

Abstract

The nonlinear behaviors of the dielectric and piezoelectric responses of 〈001〉 oriented Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) single crystals for x=4.5% and 8% have been investigated as a function of ac electric fields and dc bias fields. At relatively low applied fields, the polarization and strain of PZN-PT single crystals poled along the 〈001〉 direction show little hysteresis and have a linear dependence on the applied field, which is a consequence of engineered domain stability. Hence the dielectric and piezoelectric coefficients of the material do not exhibit any field dependence. However, when the applied electric field exceeds a threshold value, the strain and dielectric responses become nonlinear. The dielectric and piezoelectric constants are a function of the applied field, and hysteresis loops are observed. The results suggest that the observed nonlinear behavior in the PZN-PT single crystals is caused by domain motion/switching in response to the large ac fields. A positive dc bias effectively stabilizes the domain configuration in the crystals and enhances the linear response. The threshold field, at the onset of nonlinearity, is a linear function of the dc bias field in the field range investigated.