Piezoelectric properties and phase transitions of PbNi/sub 1/3/Nb/sub 2/3/O/sub 3/-PbTiO/sub 3/-PbZrO/sub 3/ ceramics

In this study, the phase transition behavior of PbNi/sub 1/3/Nb/sub 2/3/O/sub 3/-PbTiO/sub 3/-PbZrO/sub 3/ (PNN-PT-PZ) ceramics was investigated. Dielectric properties in PNN-PT-PZ ceramics with the compositions near morphotropic phase boundary (MPB) are studied as a function of temperature. The ceramics with tetragonal phase at room temperature only have a phase transition from tetragonal to cubic with elevated temperature. The ceramics with rhombohedral phase at room temperature show the phase transitions from rhombohedral to tetragonal and from tetragonal to cubic with the increase of temperature. The studies revealed the MPB has a curvature. The large longitudinal electromechanical coupling coefficient (k/sub 33/=0.8) is obtained in the composition along the curvature.