Switchable assembly of ultra narrow CdS nanowires and nanorods

We report on a simple route for the production of uniform and ultra narrow wurtzite CdS nanowires and nanorods. The nanorods are medium friendly (can exist in organic and aqueous phase) thus making them flexibly suitable for various applications. The centimeter range switchable ordering of the nanowires/rods into 3D microstrings by application of low magnitude DC electric field simply via two graphite electrodes is demonstrated. More sophisticated electrodes can be used for the same system to achieve more complex and fine patterns that can find potential use in nanoelectronics. The aligned microstrings (also wires/rods) show strong polarization dependence along their long axes. The polarized emission with respect to the unique c-axis makes the system suitable for orientation sensitive devices.

Synthesis, assembly, and optical properties of shape- and phase-controlled ZnSe nanostructures

Shape-, size-, and phase-controlled ZnSe nanostructures were synthesized by thermolysis of zinc acetate and selenourea using liganding solvents of octadecylamine (ODA) and trioctylphosphineoxide (TOPO) at different molar ratios. Materials synthesized in pure ODA resulted in uniform ultranarrow nanorods and nanowires of 1.3 nm in diameter. Morphological change from nanowire to spherical particle of larger diameter occurs with increasing TOPO/ODA ratio. Variation of the TOPO content in the mixed solvent also allows control of the crystallographic phase of ZnSe (wurtzite or zinc blende). The conditions and mechanisms of shape and phase control are discussed. Ultra-high-density networks of the ordered wires are achieved using the Langmuir-Blodgett technique in a single step as an essential stage on the route to ultra-high-density semiconductor nanocircuit fabrication.

Low temperature micelle-template assisted growth of Bi(2)S(3) nanotubes

The growth of Bi(2)S(3) nanotubes through a simple soft chemical route using the surfactant Triton-X 100 as the template at the relatively very low temperature of 115 degrees C/12 h has been reported for the first time. These nanotubes are nearly uniform in dimensions, with diameter around 120 nm and length up to 8 microm, their nature being single crystalline. The reaction conditions are optimized. Development of nanotubes and nanoparticles from the same precursor is discussed. The optical properties of the nanotubes are studied by means of UV-visible and photoluminescence spectra. The band gap calculated from the absorption spectra is found to be 1.76 eV, indicating a considerable blue shift relative to the bulk.