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We report on the synthesis of the Si∕ZnS and Si∕ZnSe core/shell nanocrystal structures produced via a two-stage thermal evaporation of SiO and ZnS or SiO and ZnSe powder mixtures. These core/shell structures display spherical and elliptical polycrystalline particles. Most of the Si∕ZnS core/shell nanocrystal structures have diameters of ∼90–160nm; the diameters of the cores and the thicknesses of the shells vary in a range of ∼50–100nm. The diameters of the Si∕ZnSe core/shell nanocrystal structures range from ∼150 to ∼200nm; the thicknesses of the shells are rather uniform, ∼30nm, and the diameters of the cores are thus in the range of ∼120–170nm. Room-temperature photoluminescence was also investigated from as-synthesized Si/ZnS and Si/ZnSe core/shell nanocrystal structures, respectively.

Here we report on the synthesis of ZnS∕SiC nanocables and SiC nanotubes and other relevant structures via a controllable two-stage thermal process using ZnS nanowires, nanoribbons, and sheets as templates. Within the cables, the ZnS cores are polytypes of fcc- and hcp-ZnS with ∼50–130nm diameter, and the SiC shells are polycrystalline β-SiC with ∼15–50nm thickness. SiC nanotubes were formed through simple removal of ZnS cores from the cables. Room-temperature photoluminescence of the SiC nanotubes displays a strong green emission band centered at ∼517nm. The nanostructures described herewith may be valuable in the blocks of advanced semiconducting devices.

Two-dimensional extremely thin single-crystalline α-Si3N4 microribbons have been achieved in bulk via a thermal decomposition nitridation. The α-Si3N4 microribbons have small thicknesses of ∼10–20 nm, large widths of ∼10–25 μm and long lengths ranging from several hundred micrometers to the order of millimeters, and have the same growth direction of [1010] crystallographic orientation and are enclosed by ±(0001) and ±(2110) facets. Room temperature cathodoluminescence from individual ribbons shows one intensive UV emission peak at ∼305 nm, and two weak and broad emission peaks at ∼540 and ∼735 nm, respectively. The form of α-Si3N4 is expected not only to possess many interesting mechanical properties, but also to have different optical properties.

Two-dimensional micrometer-sized single-crystalline ZnO thin nanosheets were achieved on a large scale, in which Zn thin nanosheets (precursor) were first grown via a thermal decomposition and reduction of the starting ZnS powder, and then converted to the ZnO nanosheets via a simple oxidation process. The ZnO nanosheets, growing along [100] or [010] direction and enclosed by ± (001) facets, have lateral dimensions up to several hundreds of microns, and thicknesses of 30–70 nm. Both room-temperature cathodoluminescence and photoluminescence measurements reveal that the present ZnO nanosheets have visible emission bands ranging from the green to red.

Monodispersed metastable cubic AgInS2 nanocrystals with an average size of around 2.5 nm are obtained via a solution-phase reaction. In contrast with the usual chalcopyrite and orthorhombic phase, Ag+ and In3+ cations in metastable cubic AgInS2 are randomly coordinated by four S2− anions. A phase transition from cation-disordered cubic to orthorhombic AgInS2 occurs with the increased reaction temperature or elongated reaction time. The photoluminescence quantum yield of cation-disordered cubic AgInS2 nanocrystals could reach 10% at room temperature, which is much higher than that of orthorhombic AgInS2 nanocrystals obtained via a similar approach.

ZnO nanowires were subjected to convergent electron beam irradiation in a 300kV transmission electron microscope. The size of perforated hexagonal pores generated by irradiation can vary with the beam size. An irradiated area is denuded layer by layer via removal of Zn and O atoms. The polar ZnO surfaces have a higher resistance to irradiation than the unpolar ones. Ultrathin nanobridges, ∼1nm thick or less, were generated through deliberate removal of Zn and O atomic monolayers.

GaS, group III-VI semiconductor compound, is known to possess a layered structure. In this letter, uniform and high-quality GaS submicrometer tubes have been synthesized via a simple high-temperature thermal reaction route. Each GaS tube is uniform in size, and has length up to tens of microns and outer diameter of ∼200-900 nm; some of the tubes are partially filled with liquid metallic Ga "rods." Photoluminescence spectrum reveals that the GaS tubes have two strong emission bands centered at ∼585 and ∼615 nm. Possible reaction processes and a rolling-up growth mechanism of as-grown GaS tubes were briefly discussed.

Wurtzite-type CdS and CdSe nanotubes have been grown via a Sn nanowire-templated route under thermal annealing. The tubes are structurally uniform and defect-free single crystals, and partially or completely filled with Sn nanowires; most of the tubes display pin-like structures showing significant tapering along their axes. Cathodoluminescence spectra reveal that CdS and CdSe nanotubes have profound emission peaks at ∼512 and ∼724nm. The luminescence intensities vary between Sn filled and unfilled tube parts. Keeping in mind that ZnS and ZnSe nanotubes may also be synthesized using the similar technique, we propose that the present method is a universal synthetic route toward single-crystalline IIB-VI group semiconductor nanotubes.