Researchers identify mechanics of single layer graphene

First discovered at the University of Manchester by Professors Andre Geim and Konstatin Novoselov, graphene is the thinnest, strongest and most conductive material ever discovered. 200 times stronger than steel yet less than an atom thick, it has a wide range of potential uses in the electronics and composites industries. For graphene to be used as nanoelectromechanical resonators or nanosensors, however, it is essential to know its structural behaviour and limitations as a mechanical material. Fabrizio Scarpa, Professor of Smart Materials and Structures at Bristol, explained: "To improve the design of graphene nanosensors it is important to understand the mechanical behaviour and the natural intrinsic damping and internal friction of graphene. Our findings indicate that graphene produced using chemical vapour deposition could be a vital alternative for nanomechanical sensor applications." The researchers used chemical vapour deposition (CVD) to grow graphene films on copper foil in a quartz tube furnace at 1030°C. They did this using a mixture of methane and hydrogen. According to Prof Scarpa, the research established some of the elastic properties of CVD-grown, single layer graphene films on copper. "The results revealed a striking difference between single and multilayered graphene films in both shear modulus and internal friction," he said. "This difference may be due to the transition of the shear restoring force from chemical bonding within a layer to interlayer interactions." The average shear modulus of the films studied was said to compare well with most of the theoretical calculations based on single layer pristine graphene structures. The high shear modulus and low internal friction pointed to a low defect density structure approaching that of the pristine graphene. "The findings suggest the use of CVD material in nanomechanical sensor applications could be a vital alternative," Scarpa concluded.