Graphene is a material that has many potential groundbreaking uses in the electronics and composites industry.
Researchers
from the University of Bristol have measured and identified for the
first time the stress and strain shear modulus and internal friction of
graphene sheets.
The research, in collaboration with the US Office of Naval Research, is published in Nano Letters.
Graphene
is made up of a single layer of carbon atoms arranged in a hexagonal
lattice. It is a promising material for the production of
next-generation displays or solar cells because it is flexible,
transparent and conductive.
For
graphene to be used as nanoelectromechanical resonators or nanosensors,
it is essential to know its structural behaviour and limitations as a
mechanical material.
Fabrizio
Scarpa, Professor of Smart Materials and Structures in the University
of Bristol’s Advanced Composites Centre for Innovation and Science
(ACCIS), said: “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 vapor deposition could be
a vital alternative for nanomechanical sensor applications.”
The
researchers, using a technique called chemical vapour deposition (CVD),
grew graphene films on copper foil in a quartz tube furnace at 1030 C
using a mixture of methane and hydrogen.
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. 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 compared well with most of
the theoretical calculations based on single-layer pristine graphene
structures. The high shear modulus and low internal friction point 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.
Shear Modulus of Monolayer Graphene Prepared by Chemical Vapor Deposition
