# Unraveling the dislocation core structure at a van der Waals gap in bismuth telluride

## TL;DR

This study uses atomic-resolution electron microscopy and theoretical modeling to reveal the dislocation core structure in bismuth telluride, highlighting the influence of van der Waals interactions on dislocation behavior relevant to thermoelectric and topological properties.

## Contribution

The paper provides the first detailed atomic-scale characterization of dislocation cores in Bi2Te3, combining experimental imaging with first-principles and Peierls-Nabarro modeling.

## Key findings

- Dislocation core spreading is mainly due to weak interlayer bonding.
- Atomic disregistry across the dislocation core was quantified.
- Theoretical models support experimental observations.

## Abstract

Tetradymite-structured chalcogenides such as bismuth telluride Bi_{2}Te_{3} are of significant interest for thermoelectric energy conversion and as topological insulators. Dislocations play a critical role during synthesis and processing of such materials and can strongly affect their functional properties. The dislocations between quintuple layers present special interest since their core structure is controlled by the van der Waals interactions between the layers. In this work, using atomic-resolution electron microscopy, we resolve the basal dislocation core structure in Bi_{2}Te_{3}, quantifying the disregistry of the atomic planes across the core. We show that, despite the existence of a stable stacking fault in the basal plane gamma surface, the dislocation core spreading is mainly due to the weak bonding between the layers, which leads to a small energy penalty for layer sliding parallel to the van der Waals gap. Calculations within a semidiscrete variational Peierls-Nabarro model informed by first-principles calculations support our experimental findings.