Gray-colored materials synthesized by calcining the precursor powders, which were produced in a microemulsion, are identified to be rutile structured SnO2 nanorods 20-45nm in diameter and several micrometers in length by x-ray diffraction, transmission with electron microscopy, and high-resolution transmission microscopy. Conspicuous far-infrared (FIR) absorption spectrum platform peaks with widths of up to 61.6 and 119 cm21 are observed, and are explained as the overlap of the surface modes of cylindrical and spheroid particles. Good agreement is achieved between FIR platform peaks and calculated results.

The thermal stability of helical multiwalled cylindrical gold nanowires is studied using molecular-dynamics simulations. From our simulation, the melting temperature of gold nanowires is lower than the bulk value, but higher than that of gold nanoclusters. It is interesting to find that the interior melting temperature in ultrathin nanowires is lower than that of the surface melting. The melting starts from the interior atoms, while the surface melting occurs at relatively higher temperature. This unique thermodynamic behavior is closely related to the interior structures. We propose that the surface melting represents the overall melting in ultrathin metallic nanowires.

The structures of free-standing zirconium nanowires 0.6-2.8nm in diameter are systematically studied by using genetic algorithm simulations with a tight-binding many-body potential. Several multishell growth sequences with cylindrical structures are obtained. These multishell structures are composed of coaxial atomic shells with the three- and four-strand helical, centered pentagonal and hexagonal, and parallel double-chaincore curved surface epitaxy. Under the same growth sequence, the numbers of atomic strands in inner and outer shells show even-odd coupling and usually differ by 5. The size and structure dependence of angular correlation functions and vibrational properties of zirconium nanowires are also discussed.

Conductance resonance of a metal-insulator-metal junction with an embedded metal cluster, which has different size and structure, is studied by the generalized Breit-Wigner formula in a tight-binding approximation. We find that a certain metal cluster possesses a specific peak pattern in the conductance data, that is, the conductance resonance peaks depend on the size and structure of metal clusters and the resonant broadening G is related to the tunnel barrier parameters. This arrangement can induce a high-quality tunneling structure with very narrow resonance peaks. Therefore, both the size effect and structure effect of the metal clusters can be predicted by observing conductance resonance of tunneling structure of embedding metal clusters in metal-insulator-metal junction. It is also possible to develop some new microelectronic devices with this structure.