Flexible graphene sheets become harder than diamond on impact
Researchers at the City University of New York have shown that two flexible graphene sheets become as harder than diamond when under pressure. The material, diamene, could be used to create ultra-light bullet proofing or wear-resistant coatings. The team also discovered diamene experienced a sudden reduction of electric current at the moment of conversion, revealing potentially interesting electronic and spintronic properties.
Researchers from The City University of New York (CUNY) describe a process for creating diamene: flexible, layered sheets of graphene that temporarily become harder than diamond and impenetrable upon impact. The material is fascinating as it is as flexible and lightweight as foil but becomes stiff and hard enough to stop a bullet on impact. Such a material may be beneficial for applications like wear-resistant protective coatings and ultra-light bullet-proof films.

The team worked to theorize and test how two layers of graphene could be made to turn into a diamond-like material upon impact at room temperature. The team also found the moment of conversion resulted in a sudden reduction of electric current, suggesting diamene could have interesting electronic and spintronic properties.

"Previously, when we tested graphite or a single atomic layer of graphene, we would apply pressure and feel a very soft film. But when the graphite film was exactly two-layers thick, all of a sudden we realized that the material under pressure was becoming extremely hard and as stiff, or stiffer, than bulk diamond" the team said.

The researchers used atomistic computer simulations to model potential outcomes when pressurizing two layers of graphene aligned in different configurations. They then used an atomic force microscope to apply localized pressure to two-layer graphene on silicon carbide substrates and found perfect agreement with the calculations. Experiments and theory both show that this transition does not occur for more than two layers or for a single graphene layer.