Crystallographic and Dielectric Properties in the Solid Solution Systems Pb(Fe_2⁄3W_1⁄3)O₃–Pb(Mg_1⁄3Ta_2⁄3)O₃ and Pb(MgW)_1⁄2O₃–Pb(FeTa)_1⁄2O₃

Abstract

It was found that complete solid solutions are formed in the systems of Pb(Fe_2⁄3W_1⁄3)O₃–Pb(Mg_1⁄3Ta_2⁄3)O₃ and Pb(MgW)_1⁄2O₃–Pb(FeTa)_1⁄2O₃. Pb(Fe_2⁄3W_1⁄3)O₃ and Pb(Mg_1⁄3Ta_2⁄3)O₃ are disordered perovskite type ferroelectrics, nevertheless the ordered arrangement of ions in the octahedral positions is formed to some degree in a certain region of intermediate composition. In the case of Pb(MgW)_1⁄2O₃–Pb(FeTa)_1⁄2O₃, the state changes from antiferro- to ferro-electric at about 70 mole percent of Pb(FeTa)_1⁄2O₃. The X-ray intensity of superlattice reflections was analyzed based on two different models. To confirm the ferro- or antiferro-electric behavior, the permittivity was measured in Pb(MgW)_1⁄2O₃–Pb(FeTa)_1⁄2O₃ system under applying d.c. bias field, and forced transition from antiferro to ferro-electric state was observed to occur in the biasing cycle.