Influence of Combined Electromechanical Loading on Dielectric Properties of (1−x) PbMg_1/3Nb_2/3O₃-xPbTiO₃ Single Crystals (x = 0.1 and 0.21)

Abstract

Single crystals of 0.9PbMg_1/3Nb_2/3O_3–0.1PbTiO₃ and 0.79PbMg_1/3Nb_2/3O_3–0.21PbTiO₃ were grown by the flux method from PbO-Pb₃O₄-B₂O₃ system as a solvent. The measurements of temperature/frequency dependence of the permittivities of these crystals under uniaxial pressure (0–1000 bar) applied parallel to the ac electric field have been carried out. It was found that uniaxial pressure significantly influences dielectric properties of these crystals. With the increase of pressure the maximum intensity in ϵ(T) curve decreases, becomes more diffuse, shifts towards higher temperatures, and dielectric dispersion decreases. It was concluded that the applied uniaxial pressure or increasing the Ti-ions content in PbMg_1/3Nb_2/3O₃-PbTiO₃ solid solutions induces similar effects. The results were discussed in term of an elastic changes in inter-ionic distances in the crystal structure and nanoregions switching under the action of pressure.