Stability and strength of monolayer polymeric C$_{60}$

TL;DR

This study uses first principles calculations to analyze the stability and strength of monolayer polymeric C60, revealing that the quasi-hexagonal phase is intrinsically stronger and more stable than other phases, explaining experimental observations.

Contribution

It provides a detailed stability and strength analysis of different monolayer fullerene phases, highlighting the quasi-hexagonal phase's superior properties.

Findings

Quasi-hexagonal phase is thermodynamically least stable at all temperatures.

Despite this, it exhibits high dynamic and mechanical stability.

Strong covalent C-C bonds underpin its high stability and strength.

Abstract

Two-dimensional fullerene networks have been synthesized in several forms [Hou et al., Nature 606, 507 (2022)], and it is unknown which monolayer form is stable at ambient condition. Using first principles calculations, I show that the believed stability of the quasi-tetragonal phases is challenged by mechanical, dynamic or thermodynamic stability. For all temperatures, the quasi-hexagonal phase is thermodynamically least stable. However, the relatively high dynamic and mechanical stabilities suggest that the quasi-hexagonal phase is intrinsically stronger than the other phases under various strains. The origin of the high stability and strength of the quasi-hexagonal phase can be attributed to the strong covalent C$-$C bonds that strongly hold the linked C$_{60}$ clusters together, enabling the closely packed hexagonal network. These results rationalize the experimental observations that so far only the quasi-hexagonal phase has been exfoliated experimentally as monolayers.