J.Z. Liu

Morphology-controlled synthesis, growth mechanism, optical and microwave absorption properties of ZnO nanocombs

ZnO nanocombs and nanorods with different morphologies have been successfully synthesized through a simple metal vapour deposition route at 600-750 degrees C using pure zinc powder or zinc and graphite powders as source materials. The structures and morphologies of the products were characterized in detail by using x-ray diffraction, scanning electron microscopy, transmission electron microscopy and laser Raman spectrometer. The morphologies of the products can be easily controlled by tuning the following four factors: reaction temperature, the distance between the source and the substrates, the kinds of substrates and the kinds of precursors. Possible growth mechanisms for the formation of ZnO nanostructures with different morphologies are discussed. Photoluminescence studies show that there are sharp UV and broad defect-related green emissions for all products. Relative intensity of the UV to defect-related green emissions decreases from ZnO nanorods to nanocombs. Microwave absorption properties of these nanocombs are also investigated. The value of the minimum reflection loss is -12 dB at 11 GHz for the ZnO nanocomb composite with a thickness of 2.5 mm.

Red light photoluminescence emission from Mn and Cd co-doped ZnS one-dimensional nanostructures

Wurtzite ZnS one-dimensional (1D) nanostructures with Mn and Cd as dopants were synthesized rapidly with Zn and S in the vapour phase. The Au-film coated Si wafers were used as substrates. Photoluminescence measurements were carried out at room temperature on the Mn-doped, Cd-doped and Mn, Cd co-doped ZnS 1D nanostructures. A red light emission band around 636 nm was found from the Mn and Cd co-doped samples. The mechanism of energy transfer for this emission is discussed.

Fabrication, structure, magnetic properties of highly ordered cobalt disulfide nanowire arrays

Highly ordered arrays of parallel CoS2 nanowires with a diameter of about 50 nm and a length up to about 50μm were synthesized by two electrical fields in an anodized aluminum oxide film. In this letter, fabrication, structure, magnetic properties of highly ordered magnetic cobalt disulfide nanowires arrays were studied. Also, a growth mechanism has been speculated.

Characterization of the single crystalline iron sulfide nanowire array synthesis by pulsed electrodeposition

Magnetic material Fe7S8 nanowire arrays have been successfully synthesized by pulsed electrodeposition in porous anodized aluminum oxide template. X-ray diffraction results show that the as-synthesized nanowires are single crystalline and have a highly preferential orientation. Scanning electron microscopy and transmission electron microscopy observations indicate that the ordered Fe7S8 nanowire arrays are uniform with a diameter of 50nm and length up to several tens of micrometers. The temperature variation of the magnetic properties has also been studied.

Overgrowing single crystalline ZnB2O4 on multiwall carbon nanotubes: Straightening the curly tubes

Single crystals of ZnB2O4 have been grown from a supercooled molten ZnO-B2O3 system on multiwall carbon nanotubes. Transmission electron microscopy investigations indicated that the originally curly carbon nanotubes were well straightened after the single-crystal coating. The coating and straightening mechanism are discussed.