AVS 50th International Symposium
    Nanometer Structures Tuesday Sessions
       Session NS-TuM

Paper NS-TuM7
Mo@sub 3@Se@sub 3@ Nanowires - Mechanical and Electrical Properties at the Nanoscale

Tuesday, November 4, 2003, 10:20 am, Room 308

Session: Nanowires
Presenter: A. Heidelberg, Trinity College Dublin, Ireland
Authors: A. Heidelberg, Trinity College Dublin, Ireland
J.W. Schultze, Heinrich-Heine-Universität Düsseldorf, Germany
G. Staikov, Forschungszentrum Jülich, Germany
J.J. Boland, Trinity College Dublin, Ireland
Correspondent: Click to Email
Low dimesional organic and inorganic materials like nanowires and nanotubes have attracted much interest as potential building blocks for nanotechnology. This interest can be traced to the novel structural and electronic properties of these materials. Here we describe a study that measures the electronic and mechanical properties of the inorganic polymer (LiMo@sub 3@Se@sub 3@)@sub n@ together with nanowire-networks that have been synthesized by exchanging the Li-counterion with different alkylammonium- and pyridinium-ligands. (LiMo@sub 3@Se@sub 3@)@sub n@ forms quasi-1D crystals and is structurally related to the Chevrel phases. It can be viewed as a condensation polymer of Mo@sub 3@Se@sub 3@ units. The crystals can be dissolved in polar solvents with @epsilon@ > 45. In these solvents the crystals disassemble into single nanowires with a diameter of 0.6 nm (from crystal data and TEM) and bundles of nanowires, depending on the solutions concentration. From solution, single nanowires, bundles of nanowires or films of nanowires can be cast on various substrates. Both, the wires themselves as well as the nanowire films are highly conductive but susceptible to electrical degradation (oxidation) in air. The ion exchanged wires form self assembled networks with an inter-wire spacing determined by the length of the side chain of the alkylammonium- and pyridinium-ligands. Conductivity measurements on these nanowire networks at different temperatures and oxidation times show that conduction is activated and occurs via a percolation mechanism. The mechanical properties of single nanowires or bundles were studied using a SPM-nanomanipulator. This instrument allows us to controllably apply forces (µN-nN range) to supported Mo@sub 3@Se@sub 3@-nanowires to effect nanoscale manipulations. Using the lateral force data of the manipulations, the mechanical properties like Youngs modulus and tensile strength of the wires can be measured.