Sr-doped PbZr1-xTixO3 ceramic:: structural study and field-induced reorientation of ferroelectric domains

Sr-doped PZT ceramic, with a composition in the morphotropic phase boundary, was synthesised by solid state reaction. In a first step, from room temperature X-ray powder diffraction data, the structures of the tetragonal (space group P4mm, Z = 1, a(t) = 4.010((l)) Angstrom and c(t) = 4.123((l)) Angstrom) and rhombohedral (space group R3m, Z = 3, a(hex) = 5.755((4)) Angstrom and c(hex) = 7.089((l)) Angstrom) phases have been refined using a Rietveld-type method. Chemical occupancies, cation displacements and spontaneous polarisation were derived for the two coexisting phases. Moreover, to investigate the ferroelectric domains reorientation under a static electrical field, the ceramic was poled and then analysed by X-ray powder diffraction. The effect of the electrical field on the macroscopic polarisation of the ceramic was studied using the ratios of selected Bragg reflections intensities. An electrical field of 1 kV mm(-1) necessary to trigger the domains reorientation in the two phases was determined and the percentage of domains switching has been estimated from simple models. On the other hand, to appreciate the degree of orientation, diffraction patterns were simulated using a preferred orientation function. Finally, the depoling process of the ceramic has been studied from successive thermal treatments. (C) 2000 Elsevier Science S.A. All rights reserved.