Glass-like structure of a lead-based relaxor ferroelectric

Abstract

It has been shown [Bosak, Chernyshov, Vakhrushev & Krisch (2012).Acta Cryst.A68, 117–123] that detailed experimental three-dimensional maps of diffuse scattering in lead-based relaxors do not agree with those expected from the concept of polar nanoregions and/or polar nanodomains. Instead, the observed diffuse scattering can be successfully parameterized in terms of a pseudo-dynamical matrix, having a shape very similar to that of the thermal diffuse scattering. Here the parameterization is extended and used to generate the disordered atomic configurations. The analysis of the resulting displacement patterns retrieved for lead ions shows that a static snapshot of the relaxor structure corresponds to the specific dipole glassy state that is characterized by local polarization and its projection onto the selected direction. The recovered structural model agrees with the observed behaviour of dielectric susceptibility as well as the existence of a wide-range hierarchy in the relaxation times in these materials.