Search

The bulk synthesis of uniform liquid Gallium (Ga) columns, which are encapsulated into carbon nanotubes through high-temperature chemical reaction between Ga and CH(sub 4), are reported. The results reveal that the condensation of a Ga vapor and carbon clusters generates Ga-filled carbon nanotubes.

Crystalline tubular magnesium oxide nanostructures were obtained through carbon-thermal evaporation of a MgO powder. Gallium oxide was added into the mixture of MgO and carbon. The reduction of gallium oxide by carbon resulted in gallium vapor at high temperatures. Condensed gallium droplets catalyzed the anisotropic growth of tubular MgO nanostructures in situ. The products were characterized by X-ray powder diffraction technique, scanning electron microscopy, and high-resolution microscopy. All the analyses indicated that the prepared tubular MgO nanostructures are, in fact, single crystals. [ABSTRACT FROM AUTHOR]

Epitaxial semiconducting heterostructures: side-to-side Si-ZnS, Si-ZnSe biaxial nanowires, and sandwichlike ZnS-Si-ZnS triaxial nanowires were grown via a simple two-stage thermal evaporation of mixed SiO and ZnS or SiO and ZnSe powders under a precise temperature control. Each nanowire had a uniform diameter of 40-120 nm and length ranging from several to several tens of micrometers. Subnanowires of Si, ZnS, and ZnSe within them had a diameter of 20-50, 40-60, and 20-50 nm, respectively. The optical property (nanoscale cathodoluminescence) was also investigated from these new structures. It is proposed that the Si nanowires formed through disproportionation of SiO to Si in the first evaporation stage and then served as one-dimensional nanoscale substrates (or templates) for an epitaxial growth of ZnS or ZnSe nanowires in the following thermal evaporation of ZnS or ZnSe powders. The present results suggest that the simple method might be useful for the synthesis of many other heterostructures containing Si and II-VI or III-V semiconducting composite nanowires to meet the growing demands of nanoscale science and technology. [ABSTRACT FROM AUTHOR]