Stabilization of Polar Nano Regions in Pb-free ferroelectrics

TL;DR

This study uses dynamic pair distribution function analysis to reveal how solid-solution additions stabilize polar nano regions in Pb-free Ba(Zr,Ti)O3 ferroelectrics, enhancing their local atomic correlations and functional properties.

Contribution

It demonstrates the effectiveness of dynamic pair distribution function technique in understanding atomic dynamics and stabilization of polar nano regions in Pb-free ferroelectrics.

Findings

Optimal Zr substitution slows atomic displacement dynamics.

Increased local dipole correlation below THz frequencies.

Technique provides new insights into disordered ferroelectric materials.

Abstract

Formation of polar nano regions through solid-solution additions are known to enhance significantly the functional properties of ferroelectric materials. Despite considerable progress in characterizing the microscopic behavior of polar nano regions, understanding their real-space atomic structure and dynamics of formation remains a considerable challenge. Here, using the method of dynamic pair distribution function, we provide direct insights into the role of solid-solution additions towards the stabilization of polar nano regions in the Pb-free ferroelectric of Ba(Zr,Ti)O3. It is shown that for an optimum level of substitution of Ti by larger Zr ions, the dynamics of atomic displacements for ferroelectric polarization are slowed sufficiently, which leads to increased local correlation among dipoles below THz frequencies. The dynamic pair distribution function technique demonstrates unique capability to obtain insights into locally correlated atomic dynamics in disordered materials, including new Pb-free ferroelectrics, which is necessary to understand and control their functional properties.