- Scientists developed a new material called diamene by compressing two graphene layers.
- Diamene is extremely thin yet harder than diamond under specific conditions.
- It will be used in developing wear-resistant protective coating and lightweight bullet-proof films.
Scientists at the ASRC (Advanced Science Research Center), Graduate Center, City University of New York, developed two thin layers of graphene that act as a diamond-like material upon impact. These flexible layered sheets can temporarily become harder than diamond and impenetrable upon impact at room temperature.
Diamond and Graphite are both entirely made of carbon, but the structure and arrangement of atom differ in each material, which gives them different properties, like electric conduction, flexibility and hardness. This new technique alters the graphite at atomic level so that it can take advantage of other carbon material properties in particular scenarios.
Researchers have named this new material diamene. Each graphene layer in it is about one-atom thick, and it contains some intriguing electronic and spintronic properties. You read it right, it’s thinner than Aluminum foil. Also, it is quite interesting that graphene-diamond transition occurred with exactly 2 layers of graphene – any less or more did not work.
The Making of Diamene
The chemistry associate professor, Angelo Bongiorno, at City University of New York, developed the theory of making diamene. Before starting any experiment, his team used atomistic computer simulations to model possible outcomes when pressurizing graphene’s two layers aligned in distinct configuration.
Material provided by City University of New York
The team used an atomic force microscope to pressurize two-layer graphene on silicon carbide substrate and things went exactly according to the plan. Both theory and experiment show graphite-diamond transition doesn’t occur for a single or more than two graphene layer.
Photo credit: Ella Maru Studio
More specifically, they used sub-ångström-resolution modulated nano indentation (MoNI) 19 atomic force microscopy (AFM) experiments, conductive AFM, micro-hardness measurements and density functional theory calculations to examine the mechanical properties of multi-layer graphene films on SiC.
The two layers of graphene on SiC (0001) exhibits a diamond-like hardness and reversible drop in electrical conductivity upon impact. According to the density functional theory, two-layer graphene transforms into a diamond like film upon compression, generating elastic deformation and sp2 to sp3 chemical alterations. The results show that two layer stacking configuration controls the conformation of diamond-like film, and in a multilayer film, it hinders the phase transformation.
The sp2 to sp3 structural and chemical changes occur regardless of the graphene’s two layers stacking configuration. They are favored by buckling distortions of the buffer layer in contact with the reactive Sic (0001) substrate, and occur more favorably by decreasing the lattice mismatch at the interface between buffer layer and substrate.
Moreover, the density functional theory calculations show that diamond-like films obtained by compressing two-layer graphene can exhibit an elastic modulus as large as 1 TPa, and formation of diamond like structure is not prevented by the lack of chemical species to passivate and stabilize the surface of the outer film.
Overall, the new material is an interesting candidate for pressure-activated, adaptive, extremely thin and hard coating, and for force-controlled dissipation switches.
Reference: Nature Nanotechnology | doi:10.1038/s41565-017-0023-9
This new research will likely have tons of applications from developing wear-resistant protective coating to lightweight bullet-proof films. It not only holds the promises of revolutionizing semiconductor, display and sensor technology, but also lead to breakthroughs in quantum physics studies.
Researchers also believe that in future, it might be used in making biomedical sensors, transparent conducting materials and ultra-light yet strong aircraft.
It also opens up possibilities for studying graphite-diamond phase transition in 2D materials. The future work may explore techniques to stabilize the transition and allow for further applications for the final outcomes.