DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF THE THERMALLY ANNEALED PB(ZN,MG)(1 3)NB2/3O3-PBTIO3 SYSTEM ACROSS THE RHOMBOHEDRAL TETRAGONAL MORPHOTROPIC PHASE/

Effects of thermal annealing on the dielectric/piezoelectric propertie s of Pb(Zn, Mg)(1/3)Nb2/3O3-PbTiO3 ceramics (PZMN-PT with Zn/Mg = 6/4) were examined across the rhombohedral/tetragonal morphotropic phase b oundary (MPB). Examination of the lattice parameters and the rhombohed ral angle indicated that the MPB is in the vicinity of 24 mol% PbTiO3. Both the relative dielectric permittivity (epsilon(r)) and the piezoe lectric constant (d(33))/electromechanical coupling constant (k(p)) we re increased by thermal annealing (800-900 degrees C) after sintering at 1150 degrees C for 1 h. The observed improvements in the dielectric and piezoelectric properties were attributed to the elimination of Pb O-rich amorphous intergranular layers (about 1 nm thickness) induced b y thermal annealing. Both the dielectric analysis using the series mix ing model and the microscopic examination by transmission electron mic roscopy supported this conclusion.