Charged domain walls and crystallographic microstructures in hybrid improper ferroelectric Ca$_{3-x}$Sr$_x$Ti$_2$O$_7$

TL;DR

This study investigates the structure of charged domain walls in the ferroelectric material Ca$_{3-x}$Sr$_x$Ti$_2$O$_7$ using transmission electron microscopy, revealing complex microstructures that influence their formation and properties.

Contribution

It provides detailed microscopic characterization of charged domain walls in Ca$_{3-x}$Sr$_x$Ti$_2$O$_7$, highlighting their size, shape, and interaction with conventional domain walls, which was previously not well understood.

Findings

Wavy charged domain walls are observed over >5 μm.

Short charged-domain-wall fragments (10-200 nm) are intercepted by 180° domain walls.

Unusual charged domain structures are revealed in Ca$_{3-x}$Sr$_x$Ti$_2$O$_7$.

Abstract

The charged domain walls in ferroelectric materials exhibit intriguing physical properties. We examine herein the charged-domain-wall structures in Ca$_{3-x}$Sr$_x$Ti$_2$O$_7$ using transmission electron microscopy. When viewed along the [001] axis, the wavy charged domain walls are observed over a wide range ($>$5 $\mu$m). In contrast, short charged-domain-wall fragments (from 10 to 200 nm long) occur because they are intercepted and truncated by the conventional 180$^{\deg}$ domain walls. These results reveal the unusual charged domain structures in Ca$_{3-x}$Sr$_x$Ti$_2$O$_7$ and will be useful for understanding their formation process.