Synthesis, structure and dielectric properties of (1-x)[0.9BiFeO ₃-0.1DyFeO₃]-xPbTiO₃ pseudo-binary ceramics

In order to develop multiferroics with large magnetization and polarization, we have prepared a series of (1-x)[0.9BiFeO₃-0. 1DyFeO₃]-xPbTiO₃ [BDF-xPT] solid solution ceramics by solid state reaction. X-ray diffraction reveals that, with the increase of PbTiO₃ concentration, the solid solution transforms from a rhombohedral to a tetragonal phase with the presence of a morphotropic phase boundary (MPB) region located at 0.28≤x≤0.40 at room temperature, in which the rhombohedral, tetragonal and orthorhombic phases coexist. The temperature dependence of the dielectric permittivity indicates that the Curie temperature decreases with the increasing amount of PbTiO₃. Based upon the structural analysis and dielectric characterization, a preliminary phase diagram for the BDF-xPT pseudo-binary system has been proposed. It is found that the ceramics of compositions around the MPB exhibits much better dielectric properties with dielectric constant of the BDF-0.37PT ceramics reaching 459 at 1 kHz, confirming the beneficial effects of the MPB on the dielectric performance.