Graphene-Based Materials and Their Mechanical Properties

Graphene-based materials encompass single-layer and few-layer graphene as well as their pressure- or chemically modified derivatives, notably diamene and diamondene. Pristine graphene exhibits exceptional in-plane stiffness and strength, with a Young’s modulus approaching one terapascals and intrinsic tensile strength in the order of 100 gigapascals. Introduction of sp³ bonding via high pressure or surface functionalisation transforms sp²-bonded layers into ultrathin diamond-like films, greatly enhancing hardness and wear resistance while preserving low mass and high thermal conductivity. Layer number, stacking order and chemical termination critically influence elastic modulus, hardness, fracture toughness and frictional response. Advanced mechanical characterisation techniques, including sub-ångström indentation, reveal how atomic-scale phase transitions and interlayer interactions govern macroscopic performance. These insights drive the design of robust flexible electronics, nanoscale sensors, protective coatings and high-frequency resonators, underscoring the global significance of graphene-based mechanics in next-generation technologies.

Research from Nature Portfolio

Spectroscopic studies of bilayer graphene under high pressure have provided the first direct evidence of a two-dimensional diamond phase. Raman measurements demonstrate a pressure-activated conversion of sp² to sp³ bonding, yielding a continuous diamondene matrix within remaining graphene domains. Molecular simulations elucidate the role of chemical groups in stabilising sp³ networks, while vibrational signatures confirm a Kohn anomaly breakdown as a hallmark of the emerging diamond lattice.

Innovations in ultra-shallow indentation techniques have enabled non-destructive measurement of atomic-thin film mechanics. By applying modulated oscillations below one ångström amplitude, researchers quantified contact stiffness and indentation modulus of graphene and diamond-coated substrates with sub-ångström depth resolution. This approach revealed that even nanometre-thick diamond films exhibit stiffness near 1 TPa and that the transverse modulus of two-dimensional layers can be probed without substrate interference, opening new pathways for characterising ultra-hard coatings and monolayer materials.

Research from all publishers

Studies on epitaxial graphene-coated silicon carbide have shown up to a 100 percent increase in surface hardness at low indentation loads and a 30 percent enhancement at higher loads. Nanoindentation experiments reveal that pressure-induced formation of a diamene film beneath the indenter raises both hardness and yield point, attributed to the sp³ diamond-like structure generated in situ. These results demonstrate the potential of two-layer graphene films to reinforce wide-bandgap substrates for extreme-wear applications.

First-principles investigations of diamane frictional behaviour reveal contrasting nanofriction coefficients for hydrogenated and fluorinated films. Calculations indicate that fluorinated diamane achieves friction comparable to graphene owing to a dense surface charge layer, whereas hydrogenated diamane exhibits roughly double the friction due to weaker interlayer repulsion. These findings inform the design of low-friction nanoscale coatings and lubricants based on tailored surface chemistry.

Graphene-Based Materials and Their Mechanical Properties publication trend

The graph below shows the total number of articles in graphene-based materials and their mechanical properties across all publications each year (not limited to Nature Index journals).

Technical terms

Young’s modulus: Measure of material stiffness defined as stress divided by strain in the elastic regime.

Hardness: Resistance of a material to localised plastic deformation or indentation.

Nanoindentation: Technique measuring mechanical response by pressing a sharp tip into a surface with nanometre-scale precision.

Diamene: Ultrathin diamond-like film formed by pressure-induced sp³ bonding in bilayer or few-layer graphene.

Diamondene: Two-dimensional diamond phase predicted and observed under high pressure in chemically activated bilayer graphene.

References

1. Giant Increase of Hardness in Silicon Carbide by Metastable Single Layer Diamond‐Like Coating. Advanced Science (2023).
2. Raman evidence for pressure-induced formation of diamondene. Nature Communications (2017).
3. Å-Indentation for non-destructive elastic moduli measurements of supported ultra-hard ultra-thin films and nanostructures. Scientific Reports (2019).
4. First-Principles Study on the Nanofriction Properties of Diamane: The Thinnest Diamond Film. Nanomaterials (2022).