Dielectric and Piezoelectric Properties of 0.91Pb(Zn1/3Nb2/3)O3-0.09PbTiO3 Single Crystals

The dielectric, piezoelectric and elastic properties of 0.91Pb(Zn_1/3Nb_2/3)O₃-0.09PbTiO₃ single crystals have been investigated as functions of temperature and applied electric field. Two multiple phase transitions at 68°C and 178°C, the crystal changing from the rhombohedral ferroelectric phase to tetragonal ferroelectric and then to cubic paraelectric, have been observed. Both the transitions are of first-order, but both are slightly diffused. Significant increases in the dielectric, piezoelectric and elastic constants are observed at the lower transition point. In particular, the sample poled along the pseudo-cubic [001] axis reveals anomalously large piezoelectric and electromechanical coupling constants at room temperature in the rhombohedral phase (d_[001]//{=}1500× 10^-12 C/N, k_[001]//{=}0.92).