The electrochemical deposition of Au/Co multilayers into 20 μm‐thick ion track etched polycarbonate membranes with pore diameters of 110–150 nm was studied in a single electrolyte containing cobalt sulfate, gold cyanide, and citric acid. Cyclic voltammetry, chronoamperometry, and pulse‐potential experiments were used to determine the deposition conditions for pure Au and 98 wt.‐% Co layers. The Co‐rich metallic nanowires were deposited at –1100 mV and the Au nanowires at –490 mV vs. Ag/AgCl. Under open‐circuit conditions an Au‐displacement reaction occurred. Open‐circuit conditions were applied in combination with a steep ramp between the Co and Au potential pulses to avoid the otherwise severe Co dissolution when the potential was switched to less negative values. Scanning and transmission electron microscopy of the deposited multilayered nanowires revealed dense and well‐defined layer interfaces. X‐ray diffraction investigations of 20 μm long Au and Co nanowires showed that the Au deposits exhibit a face‐centered cubic (fcc) <111> texture, while the Co deposits exhibit a hexagonal close‐packed (hcp) (002) structure. The magnetic measurements of 12 nm Co/4 nm Au nanowires for fields applied parallel and perpendicular to the film plane indicate a low remnant magnetization.
Metallic Au nanowires were electrochemically synthesized in 20 µm thick ion track etched polycarbonate membranes with the nominal pore diameter of 200 nm. Scanning and transmission electron microscopy analysis and x-ray diffraction of samples revealed that the nanowires are dense with a fcc [Formula: see text] texturing. The I-V characteristics of a single Au nanowire were investigated using a four-point microprobe set-up. The Au nanowire was placed in electrical contact with electrodes patterned on planar substrates using a dual-beam focused ion beam technique. The resistivity of the Au nanowires was found to be 2.8 × 10(-4) Ω cm.
Tablets of microcrystalline cellulose were formed at different compaction pressures and physical properties, such as pore size distribution, surface area, and pore surface fractality, were extracted from N2 adsorption isotherms. These properties were compared to previously published data on the water-induced ionic conductivity of the tablets. The conduction process was shown to follow a percolation model with a percolation exponent of 2 and a porosity percolation threshold of approximately 0.1. The critical pore diameter for facilitated charge transport was shown to be in the 5-20 nm range. When the network of pores with a diameter in this interval is reduced to the point where it no longer forms a continuous passageway throughout the compact, the conduction process is dominated by charge transport on the surfaces of individual microfibrils mainly situated in the bulk of fibril aggregates. A fractal analysis of nitrogen adsorption isotherms showed that the dominant interface forces during adsorption is attributed to surface tensions between the gas and the adsorbed liquid phase. The extracted fractal dimension of the analyzed pore surfaces remained unaffected by the densification process at low compaction pressures (< approximately 200 MPa). At increased densification, however, pore-surface structures smaller than approximately 100 nm become smoother as the fractal dimension decreases from approximately 2.5 at high porosities to approximately 2.3 for the densest tablets under study.
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