Experimental Demonstration and Transformation Mechanism of Quenchable Two-dimensional Diamond

TL;DR

This paper reports the successful experimental synthesis of high-quality 2D diamond, revealing its structural, optical, and transformation properties, and elucidates the atomic mechanisms underlying its formation from graphite.

Contribution

It demonstrates a novel method to produce 2D diamond via laser-heating graphene and uncovers the transition mechanism involving a rhombohedral intermediate phase.

Findings

High-quality 2D diamond with controlled thickness achieved.

Tunable optical bandgap and thermal stability based on sp3 content.

Atomic structure analysis reveals rhombohedral phase mediates graphite to diamond transition.

Abstract

Two-dimensional (2D) diamond has aroused tremendous interest in nanoelectronics and optoelectronics, owing to its superior properties and flexible characteristics compared to bulk diamond. Despite significant efforts, great challenges lie in the experimental synthesis and transformation conditions of 2D diamond. Herein, we have demonstrated the experimental preparation of high quality 2D diamond with controlled thickness and distinguished properties, realized by laser-heating few-layer graphene in diamond anvil cell. The quenched 2D diamond exhibited narrow T2g Raman peak (linewidth ~3.6 cm-1) and intense photoluminescence of SiV- (linewidth ~6.1 nm) and NV0 centers. In terms of transformation mechanism, atomic structures of hybrid phase interfaces suggested that the intermediate rhombohedral phase subtly mediate hexagonal graphite to cubic diamond transition. Furthermore, the tunable optical bandgap and thermal stability of 2D diamond sensitively depend on its sp3 concentration. We believe our results can shed light on the structural design and preparation of many carbon allotropes and further uncover the underlying transition mechanism.