Phonon transport in single-layer Boron nanoribbons

TL;DR

This study investigates phonon transport in single-layer boron nanoribbons, revealing diverse thermal conductance properties comparable to graphene and analyzing the underlying mechanisms with implications for thermal management in materials and devices.

Contribution

It provides the first detailed analysis of phonon transport in boron nanoribbons with different edge types using first principles and Green's function methods.

Findings

Thermal conductance in boron nanoribbons can match or be less than half of graphene's.

Transport properties vary significantly with edge type and anisotropy.

Mechanisms are explained through phonon dispersion and atomic bonding analysis.

Abstract

Inspired by the successful synthesis of several allotropes, boron sheets have been one of the hottest spot areas of focus in various fields. Here, we study phonon transport in three types of boron nanoribbons with zigzag and armchair edges by using a non-equilibrium Green's function combined with first principles methods. Diverse transport properties are found in the nanoribbons. At the room temperature, their highest thermal conductance can be comparable with that of graphene, while the lowest thermal conductance is less than half of graphene's. The three boron sheets exhibit different anisotropic transport characteristics. Two of these sheets have stronger phonon transport abilities along the zigzag edges than the armchair edges, while in the case of the third, the results are reversed. With the analysis of phonon dispersion, bonding charge density, and simplified models of atomic chains, the mechanisms of the diverse phonon properties are discussed. Because all boron allotropes consists of hexagonal and triangular rings, many hybrid patterns can be constructed naturally without doping, adsorption, and defects. Our results are useful in materials and devices design using boron sheets for thermal management.