Carbon based nanostructures
Carbon based nano-structures are very promising for future applications in electrical and electromechanical devices. They generally consist of graphene-like atomic layers that form tubes shapes or other shapes, such as cones. Carbon nanotubes consist of graphene layers that are rolled into concentric tubes, while for carbon fibres the graphene layers are not fully parallel to the fibre axis. Graphene itself has a high in-plane stiffness and electrical conductance, which gives the tubes a high stiffness and high electrical conductivity. Combined with their low weight one then has a material that is highly promising as flexible electrical conductors in e.g. nano-relays and super capacitors. Carbon nanofibres have a lower mechanical stiffness and electrical conductivity, but these materials are much easier to produce with accurate growth control.
The properties of these materials are to a large extent governed by the atomic structure, i.e. the build up of the nano-structures and their crystallinity. The characterisation of the nano-structure is very demanding, from an experimental point of view, and in particular studies of free-standing individual tubes are very demanding due to the small size. In this project we use especially developed instruments that enable studies of individual fibres. The measurements are done insid electron microscopes and we can then both "see" and "touch" the materials on a nano-scale level. This enables characterisations of mechanical strength and stiffness, together with electrical conductance and atomic structure.
Bending of a multi-walled carbon nanotube inside a transmission electron microscope, together with the simultaneously obtained force curve.