Visualization of Swift Ion Tracks in Suspended Local Diamondized Few-Layer Graphene

Area of Science:

• Materials Science
• Nanotechnology
• Physics

Background:

• Few-layer graphene (FLG) is a promising material with unique electronic properties.
• Controlling nanostructure formation in FLG is crucial for advanced applications.
• Ion irradiation is a method to induce structural modifications in materials.

Purpose of the Study:

• To investigate nanostructuring processes in FLG films induced by high-energy ion irradiation.
• To understand the formation mechanisms of different nanostructures under ion bombardment.
• To explore the potential for creating novel graphene-based materials with diamond interfaces.

Main Methods:

• Irradiation of FLG films with high-energy xenon (Xe) ions (26-167 MeV) at doses of 1 × 10^11-5 × 10^12 ion/cm^2.
• Analysis of structural transformations using Raman spectroscopy and transmission electron microscopy (TEM).
• Estimation of local compressive strain and pressure at ion track peripheries.

Main Results:

• Two types of nanostructures were identified: 'bunches' at low doses and nanodiamonds (ND) or specific stacking (AA', ABC) at higher energies.
• First visualization of ion tracks in graphene as diamond or diamond-like rings.
• Identified substrate absence and high ion energy as key conditions for nanodiamond formation.
• Estimated local compressive strain (~0.15-0.22%) and pressure (~0.8-1.2 GPa) at track peripheries.

Conclusions:

• High-energy ion irradiation can controllably create nanodiamonds within FLG films.
• The process enables the development of novel materials with embedded quantum dot-like diamond structures.
• Understanding strain and energy transfer is key to tailoring FLG nanostructure properties.