Effect of nanopolar regions on electrostrictive coefficients of a relaxor ferroelectric

Abstract

Volumetric electrostrictive coefficient, Qh, of PbMg1/3Nb2/3O3 (PMN) relaxor ferroelectric is investigated using a high-resolution neutron powder diffraction and a conventional strain measurement. Using the results of these experiments we: (1) derive the value of Qh of prototype cubic lattice of PMN, which is equal to Qh=(8.3±1.0)×10−2(m4/C2); (2) find the temperature dependence of the volume fraction, δV, of the polar regions in the material, and estimate that at temperatures around the dielectric permittivity maximum, Tmax, it is equal to δV≈90%; (3) estimate the magnitude of the contribution of the crystal lattice to the polarization response of PMN at temperatures around and below Tmax. These results are essential for the understanding of the nature of the polarization and strain response of relaxor ferroelectrics.