Effects of Uniaxial Pressure on the Dielectric Properties of (1-x)PbMg_1/3Nb_2/3O₃-xPbTiO₃ Single Crystals (x = 0.28 and 0.38)

Abstract

The single crystals of 0.72PbMg_1/3Nb_2/3O₃-0.28PbTiO₃ and 0.62PbMg_1/3Nb_2/3O₃-0.38PbTiO₃ were grown by a flux method from PbO-Pb₃O₄-B₂O₃ system as a solvent. The measurements of temperature/frequency dependence of the permittivities of these crystals under an uniaxial pressure (0–1000 bar) applied parallel to the ac electric field have been carried out. The experimental results revealed that uniaxial pressure significantly influenced the dielectric properties of these crystals. With the increase in pressure the maximum intensity in ϵ(T) curve decreases, becomes more diffuse and shifts towards a higher temperature, and dielectric dispersion decreases. An electrostrictive coefficient Q₁₁ was evaluated from obtained data. It was concluded, that the applied uniaxial pressure or increasing Ti-ions content in PbMg_1/3Nb_2/3O₃-PbTiO₃ solid solutions induced similar effects. The results were discussed in terms of an elastic changes in inter-ionic distances in a crystal structure and switching nanoregions/ domains under the action of pressure.

Keywords:

• Ferroelectric
• PbMg_1/3Nb_2/3O₃-PbTiO₃
• dielectric properties
• uniaxial pressure