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Abstract: Three kinds of ZnO nanowire arrays were fabricated on Au coated (110)silicon wafer by using of heating the mixture of zinc oxide (ZnO) and graphite powders at various depositing temperature. The synthesized samples were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) analytic technology, respectively. Structural analyses revealed that the morphologies and crystal microstructures of ZnO nanoarrays were related with the substrate temperature. And control to the growth morphologies can be achieved by carefully tuning the depositing temperature. The testing results to different nanowire arrays showed that the properties of field emission follow the Fowler–Nordheim law. The quais-aligned ZnO nanowire array sample synthesized at 750°C had the lowest turn-on field of 7.4V/μm, highest β of 1028. This largest emission efficiency is attributed to the clear tip and appropriate coverage density. As well as the nanowires are straight with long length and parallel to each other with good crystal quality. The experimental results could be very useful for field emission materials and other nanoelectronics device applications. [Copyright &y& Elsevier]

In order to utilize the unique properties of carbon nanotubes (CNTs) in microelectronic devices, the special hetero-junction or multiple phase structure of multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) array has been produced by chemical vapor deposition (CVD) method in porous anodic aluminum oxide (AAO) templates. The approach involves CVD process, fabrication of catalytic nanoparticle, and nanotube interconnection for orientation. The synthesized MWNT/SWNT hetero-junctions or multiple phase nanowire arrays were fully characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectrum. The multiple phase structures have the one-dimensional features of CNTs and build an ideal semiconductor–metal or metal–metal hetero-junction nanowire in the axial direction. The structural character and growing mechanism of MWNT/SWNT hetero-junctions or multiple phase nanowire arrays were also analyzed and discussed. [Copyright &y& Elsevier]

Density-graded aluminum foams provide the possibility to further improve performance under static and dynamic loading. Tailoring and precise manipulating the graded structure is highly desired. Herein, we successfully prepared density-graded aluminum foam and investigated the effects of experimental parameters, i.e. cooling rate, growth rate, holding time, on the eventual density gradient. Microstructures of cell walls were found to vary with the distance away from cooling end. A numerical model coupling the foam melt growth and solidification was developed to predict the density gradient. Once the foaming agent content was high or the holding time was limited, the model predictions were highly accurate. Mechanical properties of density-graded aluminum foam were studied by quasi-static compressive tests. The relationship between compressive stress/strain curves and density distribution was established, which made the mechanical properties of density-graded aluminum foam more tailorable. [ABSTRACT FROM AUTHOR]