Static and dynamic polar nanoregions in relaxor ferroelectric Ba(Ti1−xSnx)O3

Abstract

Relaxor ferroelectrics are materials exhibiting dielectric dispersions in their maximum permittivity temperature without macroscopic phase transition into a ferroelectric state. Their exceptional properties are exploited in a variety of dielectric and piezoelectric applications. As it is generally believed that polar nanoregions play a crucial role in relaxor behavior, there are great interests in exploring how the atomic structures affect the relaxor properties. Here, using the dark field imaging and atomic-resolution electron microscopy, we investigate the nano and atomic structure of a lead-free ferroelectric-relaxor Ba(Ti 1−x Sn x )O 3 system at high temperature. The local atom displacements and their spatial correlations are measured, and the atomic structure of static polar nanoregions in the relaxors is reported. For the materials exhibiting normal ferroelectricity, no such static polar structures can be seen. Based on our experimental observations, we suggest the static polar nanoregions are responsible for the relaxor behavior in this lead-free system.

Re‐entrant dipole glass‐like behavior and lattice dynamics of 0.65Bi(Mg1/2Ti1/2)O3‐0.35PbTiO3

“…Similar to BaTiO 3 ‐Bi(Zn 2/3 Nb 1/3 )O 3 , the large mismatches of both size and charge of the ions on the B‐site in (1‐ x )BMT‐ x PT induce polar clusters, the size and dynamics of which can play an important role on the relaxor behavior. It results in a disorder driven nucleation of polar clusters at high temperature and a subsequent frequency dispersion …”

Why Sn doping significantly enhances the dielectric properties of Ba(Ti1-xSnx)O3

“…One of the main structural features of Ba(Ti 1-x Sn x )O 3 ceramics is the diffuse scattering phenomenon in the electron diffraction patterns, which has been suggested to be caused by some nano-size structure910. Through dark-field and high-resolution transmission electron microscopy images, Xie et al11 observed PNRs that were embedded in the matrix in ceramics that exhibited relaxor behaviour. These authors suggested that these PNRs were responsible for both the relaxor behaviour and diffuse scattering phenomenon.…”

Fano resonance and dipolar relaxation in lead-free relaxors

“…Owing to their fundamental interest and also technological promise, relaxors have been studied by various techniques since their discoveries. For instance, they have been investigated by Raman, neutron elastic diffuse scattering, extended X-ray absorption fine structure, high-resolution tunnelling electron microscopy, piezoresponse force microscopy, phenomenology and numerical simulations 7,13,19,20,26,27,[36][37][38][39][40][41] . On the other hand, there is an important aspect of their properties that has been much less documented because of experimental and computational challenges to overcome, that is, their terahertz (THz) dynamics 25,27,42,43 .…”