Dielectric and piezoelectric properties of the thermally annealed Pb(Zn,Mg)1/3Nb2/3O3–PbTiO3 system across the rhombohedral/tetragonal morphotropic phase boundary

Abstract

Effects of thermal annealing on the dielectric/piezoelectric properties of Pb(Zn,Mg)1/3Nb2/3O3-PbTiO3 ceramics (PZMN-PT with Zn/Mg = 6/4) were examined across the rhombohedral/tetragonal morphotropic phase boundary (MPB). Examination of the lattice parameters and the rhombohedral angle indicated that the MPB is in the vicinity of 24 mol% PbTiO3. Both the relative dielectric permittivity (∊r) and the piezoelectric constant (d33)/electromechanical coupling constant (kp) were increased by thermal annealing (800–900 °C) after sintering at 1150 °C for 1 h. The observed improvements in the dielectric and piezoelectric properties were attributed to the elimination of PbO-rich amorphous intergranular layers (about 1 nm thickness) induced by thermal annealing. Both the dielectric analysis using the series mixing model and the microscopic examination by transmission electron microscopy supported this conclusion.