ABSTRACT
In this paper we show the advantages of transparent high conductive films based on filled single-wall carbon nanotubes. The nanotubes with internal channels filled with acceptor molecules (copper chloride or iodine) form networks demonstrating significantly improved characteristics. Due to the charge transfer between the nanotubes and filler, the doped-nanotube films exhibit a drop in electrical sheet resistance of an order of magnitude together with a noticeable increase of film transparency in the visible and near-infrared spectral range. The thermoelectric power measurements show a significant improvement of air-stability of the nanotube network in the course of the filling procedure. For the nanotube films with an initial transparency of 87% at 514 nm and electrical sheet resistance of 862 Ohm sq-1 we observed an improvement of transparency up to 91% and a decrease of sheet resistance down to 98 Ohm sq-1. The combination of the nanotube synthesis technique and molecules for encapsulation has been optimized for applications in optoelectronics.
ABSTRACT
Holes with an average size of 2-5 nm have been created in graphene layers by heating of graphite oxide (GO) in concentrated sulfuric acid followed by annealing in an argon flow. The hot mineral acid acts simultaneously as a defunctionalizing and etching agent, removing a part of oxygen-containing groups and lattice carbon atoms from the layers. Annealing of the holey reduced GO at 800 °C-1000 °C causes a decrease of the content of residual oxygen and the interlayer spacing thus producing thin compact stacks from holey graphene layers. Electrochemical tests of the obtained materials in half-cells showed that the removal of oxygen and creation of basal holes lowers the capacity loss in the first cycle and facilitates intercalation-deintercalation of lithium ions. This was attributed to minimization of electrolyte decomposition reactions, easier desolvation of lithium ions near the hole boundaries and appearance of multiple entrances for the naked ions into graphene stacks.
ABSTRACT
The growth, composition and structure of sandwich structures (Fe-rich layer/Si-rich layer/Fe-rich silicide layer) grown on a Si(111) surface were studied by a few complementary microscopic and spectroscopic techniques with high spatial resolution. Intermixing at the Fe/Si and Si/Fe interfaces is demonstrated. Fe-rich layers grown directly on the Si(111) surface are crystalline and have abrupt but rough interfaces at both sides. The succeeding layers are disordered and their interfaces are fuzzy. The distributions of Fe and Si within the layers are laterally non-uniform. The reproducible fabrication of thin non-magnetic silicide spacers of predetermined thickness is demonstrated. Sandwich structures with such spacers exhibit exchange coupling between ferromagnetic Fe-rich layers.
