Anomalous pressure dependence of the atomic displacements in the relaxor ferroelectric PbMg${}_{1/3}$Ta${}_{2/3}$O${}_3$

Abstract

The crystal structure of the PbMg${}_{1/3}$Ta${}_{2/3}$O${}_3$ (PMT) relaxor ferroelectric was studied under hydrostatic pressure up to $\sim 7$ GPa by means of powder neutron diffraction. We find a drastic pressure-induced decrease of the lead displacement from the inversion centre which correlates with an increase by $\sim$ 50 % of the anisotropy of the oxygen temperature factor. The vibrations of the Mg/Ta are, in contrast, rather pressure insensitive. We attribute these changes being responsible for the previously reported pressure-induced suppression of the anomalous dielectric permittivity and diffuse scattering in relaxor ferroelectrics.

References in corpus (4)

• Neutron Diffuse Scattering from Polar Nanoregions in the Relaxor Pb(Mg1/3Nb2/3)O3
• Quasi-Elastic Scattering, Random Fields and phonon-coupling effects in PbMg1/3Nb2/3O3
• Disorder and relaxation mode in the lattice dynamics of PbMg${}_{1/3}$Nb${}_{2/3}$O${}_3$ relaxor ferroelectric
• Neutron scattering study of PbMg${}_{1/3}$Ta${}_{2/3}$O${}_3$ and BaMg${}_{1/3}$Ta${}_{2/3}$O${}_3$ complex perovskites