Pressure Dependence of Piezoelectric Properties of Pb(Zn1/3Nb2/3)O3-PbTiO3 Binary System Single Crystal near a Morphotropic Phase Boundary

The piezoelectric properties of a Pb[(Zn1/3Nb2/3)0.91]Ti0.09O3 binary system single crystal oriented along the [001] direction in the rhombohedral phase was investigated under pressures up to 500 MPa at 25°C. With increasing hydrostatic pressure, the change of the resonance and antiresonance frequency characteristic curves of the impedance and phase from sharp to broad ones was observed. The resonance frequency f r increased, while the antiresonance frequency f a remained almost constant. The electromechanical coupling coefficient in the k31 mode decreased markedly with pressure, and the value of the k 31 mode decreased by 18% at 500 MPa. The electromechanical coupling coefficient in the k 33 mode decreased slightly with pressure. The value of the k 33 mode decreased slightly by only 3% at 500 MPa. The large decrease in the k 31 value with pressure exhibited a marked contrast with the slight decrease in the k 33 value with pressure. The changes in the values of the elastic compliances s 11 E and s 33 E with pressure were observed to be large from the changes in f r and f a with pressure. s 11 E and s 33 E at 400 MPa were estimated to be 7.23 and 13.95×10-11 m2/N, respectively. The large k 31 in the k 31 mode is considered to be due to the mechanical softness of the PZN-PT(91/9) single crystal. On the other hand, the slight decrease in k 33 with pressure is thought, on the basis of the engineered domain concept, to be due to the stable domain configuration responsible for the longitudinal k 33 mode.