Stability and Strength of Atomically Thin Borophene from First Principles Calculations

Abstract

A new two-dimensional (2D) material, borophene (2D boron sheet), has been grown successfully recently on single crystal Ag substrates by two parallel experiments [Mannix \textit{et al., Science}, 2015, \textbf{350}, 1513] [Feng \textit{et al., Nature Chemistry}, 2016, \textbf{advance online publication}]. Three main structures have been proposed (${\beta }_{12}$, ${\chi }_3$ and striped borophene). However, the stability of three structures is still in debate. Using first principles calculations, we examine the dynamical, thermodynamical and mechanical stability of ${\beta }_{12}$, ${\chi }_3$ and striped borophene. Free-standing ${\beta }_{12}$ and ${\chi }_3$ borophene is dynamically, thermodynamically, and mechanically stable, while striped borophene is dynamically and thermodynamically unstable due to high stiffness along $a$ direction. The origin of high stiffness and high instability in striped borophene along $a$ direction can both be attributed to strong directional bonding. This work provides a benchmark for examining the relative stability of different structures of borophene.

13 pages, 6 figures

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Cited by in corpus (2)

• Current-Voltage Characteristics of Borophene and Borophane Sheets
• Borophene hydride: a stiff 2D material with high thermal conductivity and attractive optical and electronic properties