Influence of tetragonal platelets on the dielectric permittivity of 0.964Na$_{1/2}$Bi$_{1/2}$TiO$_3$-0.036BaTiO$_3$

TL;DR

This study investigates how tetragonal platelets influence the dielectric permittivity in a lead-free relaxor ferroelectric, revealing a correlation between platelet thickness and increased polarizability affecting dielectric properties.

Contribution

It introduces a temperature-dependent nanostructure model with chemically pinned tetragonal platelets in a relaxor ferroelectric, linking nanostructure to dielectric behavior.

Findings

Tetragonal platelets are embedded in a rhombohedral matrix with a cubic intermediate phase.

A clear correlation exists between platelet thickness squared and dielectric permittivity.

Increased polarizability is associated with strained and distorted lattice regions within the platelets.

Abstract

We study the temperature-dependent evolution of the octahedral tilt order in a lead-free relaxor ferroelectric and its impact on the ferroelectric properties. Using diffuse neutron scattering on a 0.964Na$_{1/2}$Bi$_{1/2}$TiO$_3$-0.036BaTiO$_3$ single crystal, we suggest a model for the temperature-dependent nanostructure of this perovskite that features chemically pinned tetragonal platelets embedded in the rhombohedral matrix, often separated by a cubic intermediate phase. Our results show a clear correlation between the squared thickness of the tetragonal platelets and the dielectric permittivity. This is interpreted as a sign for increased polarizability of the strained and distorted lattice at the center of the tetragonal platelets.