Piezoelectric properties and phase transitions of <001> oriented Pb(Zn_1/3Nb_2/3)O₃-PbTiO₃ single crystals

The temperature and electric field dependence of the piezoelectric properties and phase transitions of <001> oriented Pb(Zn_1/3Nb_2/3)O₃-xPbTiO₃ single crystals for x = 4.5% and 8% have been investigated. Both piezoelectric properties and phase transitions are strongly dependent on temperature and electric field. Our measurements of polarization and strain as a function of unipolar electric field show that the fields for the rhombohedral-tetragonal phase transition decrease linearly with temperature. In the rhombohedral phase d₃₃ increases with temperature while in the field induced tetragonal phase it is almost temperature independent. Dielectric measurements show that the temperature of the rhombohedral-tetragonal phase transition decreases with bias field. Thus, raising the temperature or applying a dc bias field can stabilize the tetragonal phase in <001> oriented PZN-PT crystals.