Rupture of amorphous graphene via void formation

TL;DR

This study analyzes void formation in amorphous graphene, revealing how line tension and pressure influence critical void size, with implications for strain engineering in 2D materials.

Contribution

It provides a combined numerical and analytical model for void energetics in amorphous graphene, highlighting the role of shear modulus and finite size effects.

Findings

Critical radius of voids at 2 eV/Ų pressure: 3.48 Š(flat), 3.31 Š(buckled)

Finite size correction to line tension inversely proportional to void radius

Shear modulus sets the lower limit of line tension in amorphous 2D materials

Abstract

Apart from its unique and exciting electronic properties, many sensor based applications of graphene are purely based on its mechanical and structural properties. Here we report a numerical and analytical study of a void in amorphous (small domain polycrystalline) graphene, and show that the energetics of a void is a balance between the line tension cost versus the increased area gain. Using the concepts of classical nucleation theory, we show that the critical radius of a void formed in amorphous graphene at constant pressure is simply the ratio of line tension at the void and the applied pressure. The values of the critical radius of the void for flat and buckled graphene are 3.48\AA ~and 3.31\AA, respectively at 2 eV/\AA${^2}$ pressure. We also show that the dominant finite size correction to the line tension is inversely proportional to the radius of the void in both flat and buckled cases. Contrary to conventional wisdom, with the help of a simple analytical model we find that the shear modulus sets the lower limit of the line tension in the samples. This makes our study relevant for other two-dimensional amorphous materials such as h-BN, phosphorene, borophene, and transition metal dichalcogenides. Our results are useful for the better understanding of polycrystalline graphene under tension and therefore have direct implications on the very fascinating field of strain engineering known as "straintronics" to manipulate or improve graphene's properties.