The structure of amorphous two-dimensional materials: Elemental monolayer amorphous carbon versus binary monolayer amorphous boron nitride

Abstract

The structure of amorphous materials has been debated since the 1930's as a binary question: amorphous materials are either Zachariasen continuous random networks (Z-CRNs) or Z-CRNs containing crystallites. It was recently demonstrated, however, that amorphous diamond can be synthesized in either form. Here we address the question of the structure of single-atom-thick amorphous monolayers. We reanalyze the results of prior simulations for amorphous graphene and report kinetic Monte Carlo simulations based on alternative algorithms. We find that crystallite-containing Z-CRN is the favored structure of elemental amorphous graphene, as recently fabricated, whereas the most likely structure of binary monolayer amorphous BN is altogether different than either of the two long-debated options: it is a compositionally disordered "pseudo-CRN" comprising a mix of B-N and noncanonical B-B and N-N bonds and containing "pseudocrystallites", namely honeycomb regions made of noncanonical hexagons. Implications for other non-elemental 2D and bulk amorphous materials are discussed.

4 figures; with Supplemental Materials

References in corpus (3)

• From Point Defects in Graphene to Two-Dimensional Amorphous Carbon
• Single-crystal hexagonal boron nitride monolayer epitaxially grown on Cu (111) thin film across a wafer
• Synthesis and properties of free-standing monolayer amorphous carbon

Cited by in corpus (5)

• Thermal transport of amorphous carbon and boron-nitride monolayers
• Near-field localization of the boson peak on tantalum films for superconducting quantum devices
• Structure and mechanical properties of monolayer amorphous carbon and boron nitride
• A Concise Review of Recently Synthesized 2D Carbon Allotropes: Amorphous Carbon, Graphynes, Biphenylene and Fullerene Networks
• Disentangling morphology and conductance in amorphous graphene