Auxetic properties of a newly proposed $\gamma$-graphyne-like material

TL;DR

This paper introduces a new 2D carbon-based material called AγG, which exhibits auxetic properties, high thermal stability, and a significant bandgap, expanding the potential applications of graphyne-like structures.

Contribution

The study proposes a novel γ-graphyne-like structure with auxetic properties and thoroughly investigates its mechanical, electronic, and thermal characteristics using molecular dynamics simulations.

Findings

AγG is thermally stable across a wide temperature range.

It exhibits a large bandgap of 2.48 eV.

AγG is confirmed to be auxetic both in vacuum and on substrates.

Abstract

In this work, we propose a new auxetic (negative Poisson's ratio values) structure, based on a $\gamma$-graphyne structure, here named $A\gamma G$ $structure$. Graphynes are 2D carbon allotropes with phenylic rings connected by acetylenic groups. The A$\gamma$G structural/mechanical and electronic properties, as well as its thermal stability, were investigated using classical reactive and quantum molecular dynamics simulations. We found that A$\gamma$G has a large bandgap of 2.48 eV and is thermally stable at a large range of temperatures. It presents a Young's modulus that is an order of magnitude smaller than that of graphene or $\gamma$-graphyne. The classical and quantum results are consistent and validate that the A$\gamma$G is auxetic, both when isolated (vacuum) and when deposited on a copper substrate. We believe that this is the densest auxetic structure belonging to the graphyne-like families.