Investigation of a high Tc piezoelectric system:: (1-x)Bi(Mg1/2Ti1/2)O3-(x)PbTiO3

(1-x)Bi(Mg1/2Ti1/2)O-3-xPbTiO(3) polycrystalline ceramics were investigated for potential as high-temperature piezoelectric materials. A morphotropic phase boundary (MPB) between tetragonal (T) and rhombohedral (R) ferroelectric (FE) phases, which exhibited enhanced piezoelectric activity and a ferroelectric-paraelectric phase transition at 478 degreesC was observed at xapproximate to0.37. Electron diffraction patterns (xless than or equal to0.37) contained discrete superlattice reflections at 1/2{hkl} positions arising from antiphase rotations of the O octahedra, consistent with R3c space group symmetry. These reflections were diffuse at the MPB (x=0.38) and absent in the T phase (x=0.5). In the unpoled state, FE R (x=0.35) ceramics revealed a polar microdomain structure whereas the T phase (x=0.5) contained classic {110} twin domain boundaries. However, poled R samples underwent a field-induced transformation to an aligned domain structure with {110} twin boundaries similar to those in the T phase. Correlations are made between structure and properties for these piezoelectric materials. (C) 2004 American Institute of Physics.