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Vapor Synthesis (vapor + synthesis)

Distribution by Scientific Domains
Polymers and Materials Science100%

Kinds of Vapor Synthesis

  • chemical vapor synthesis
    		•

    Selected Abstracts

    Nanocrystal Shape Control: Synthesis and Structure,Property Correlation in Shape-Controlled ZnO Nanoparticles Prepared by Chemical Vapor Synthesis and their Application in Dye-Sensitized Solar Cells (Adv. Funct.

    ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
    Mater.
    Chemical vapor synthesis is a convenient one-step synthesis process for the production of nanocrystalline powders. On page 875, Bacsa et al. report that by controlled variation of experimental parameters, tetrapods (as in image) or spherical ZnO nanocrystals can be selectively obtained directly from Zn metal precursor. Shape control leads to improved optical properties and a better performance when applied as electrodes in dye sensitized solar cells. [source]

    Synthesis and Structure,Property Correlation in Shape-Controlled ZnO Nanoparticles Prepared by Chemical Vapor Synthesis and their Application in Dye-Sensitized Solar Cells

    ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
    Revathi R. Bacsa
    Abstract Here, the large scale synthesis of nanocrystalline ZnO spheres and tetrapods in the size range of 8,40,nm by chemical vapor synthesis using zinc metal as precursor is described. A detailed study of the effect of experimental parameters on the morphology and yield is presented. High-resolution transmission electron microscopy images of the tetrapods show that they are formed by the self assembly of four nanorods in the vapor phase. The tetrapods have optical absorption coefficients that are one order of magnitude greater than the spheres and show intense UV luminescence whereas the spheres show only the green emission. The observed differences in the optical properties are related to the presence of surface defects present in the nanospheres. The tetrapods have increased efficiencies for application in dye sensitized solar cells when compared to spheres. [source]

    Sintering Behavior of Nanocrystalline Zirconia Doped with Alumina Prepared by Chemical Vapor Synthesis

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2000
    Vladimir V. Srdi
    Powders of nanocrystalline zirconia doped with 3,30 mol% alumina have been synthesized using chemical vapor synthesis (CVS). Dense or mesoporous ceramics of small and narrowly distributed grain and pore sizes in the nanometer range are obtained via pressureless vacuum sintering. The microstructural development of the doped samples is strongly dependent on the alumina content. Sintering of zirconia samples with 3 and 5 mol% alumina at temperatures of 1000°C for 1 h results in fully dense, transparent ceramics with grain sizes of 40,45 nm and homogeneous microstructures. [source]

    A Novel Approach for Chemical Vapor Synthesis of ZnO Nanocrystals: Optimization of Yield, Crystallinity,

    CHEMICAL VAPOR DEPOSITION, Issue 7-9 2009
    Moazzam Ali
    Abstract The experimental yield of ZnO nanocrystals decreases drastically with increasing reactor temperature in a typical chemical vapor synthesis (CVS) of ZnO nanocrystals from diethylzinc. A novel CVS set-up , a microwave plasma combined with a hot-wall zone , is described to minimize the loss of particles at higher reactor temperatures. The powder samples have been characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). It is observed that the synthesis set-up and reaction temperature have substantial influence not only on yield but also on crystallite size and crystallinity of the pure wurtzite-type ZnO nanocrystals. The lattice constants of ZnO nanocrystals increase with decreasing crystallite size. Defect densities (twin and stacking faults), as well as microstrain, decrease with increasing reactor temperature, whereas crystallinity increases. [source]

    In-Situ Preparation of Polymer-Coated Alumina Nanopowders by Chemical Vapor Synthesis

    CHEMICAL VAPOR DEPOSITION, Issue 1 2003
    M. Schallehn
    Abstract Nanocrystalline alumina particles coated with polyethylene have been prepared by a two-step chemical vapor synthesis (CVS) process using a hot-wall reactor to synthesize the nanocrystalline alumina core, and a RF plasma reactor for the subsequent polymer coating. The particle radius is about 4,nm, with the radius of the ceramic core being about 2.5,nm and the coating thickness about 1.5,nm. The powders have been characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer,Emmett,Teller (BET), small-angle neutron scattering (SANS), and high-resolution transmission electron microscopy (HRTEM). [source]

    Nanocrystal Shape Control: Synthesis and Structure,Property Correlation in Shape-Controlled ZnO Nanoparticles Prepared by Chemical Vapor Synthesis and their Application in Dye-Sensitized Solar Cells (Adv. Funct.

    ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
    Mater.
    Chemical vapor synthesis is a convenient one-step synthesis process for the production of nanocrystalline powders. On page 875, Bacsa et al. report that by controlled variation of experimental parameters, tetrapods (as in image) or spherical ZnO nanocrystals can be selectively obtained directly from Zn metal precursor. Shape control leads to improved optical properties and a better performance when applied as electrodes in dye sensitized solar cells. [source]

    Synthesis and Structure,Property Correlation in Shape-Controlled ZnO Nanoparticles Prepared by Chemical Vapor Synthesis and their Application in Dye-Sensitized Solar Cells

    ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
    Revathi R. Bacsa
    Abstract Here, the large scale synthesis of nanocrystalline ZnO spheres and tetrapods in the size range of 8,40,nm by chemical vapor synthesis using zinc metal as precursor is described. A detailed study of the effect of experimental parameters on the morphology and yield is presented. High-resolution transmission electron microscopy images of the tetrapods show that they are formed by the self assembly of four nanorods in the vapor phase. The tetrapods have optical absorption coefficients that are one order of magnitude greater than the spheres and show intense UV luminescence whereas the spheres show only the green emission. The observed differences in the optical properties are related to the presence of surface defects present in the nanospheres. The tetrapods have increased efficiencies for application in dye sensitized solar cells when compared to spheres. [source]

    Sintering Behavior of Nanocrystalline Zirconia Doped with Alumina Prepared by Chemical Vapor Synthesis

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2000
    Vladimir V. Srdi
    Powders of nanocrystalline zirconia doped with 3,30 mol% alumina have been synthesized using chemical vapor synthesis (CVS). Dense or mesoporous ceramics of small and narrowly distributed grain and pore sizes in the nanometer range are obtained via pressureless vacuum sintering. The microstructural development of the doped samples is strongly dependent on the alumina content. Sintering of zirconia samples with 3 and 5 mol% alumina at temperatures of 1000°C for 1 h results in fully dense, transparent ceramics with grain sizes of 40,45 nm and homogeneous microstructures. [source]

    A Novel Approach for Chemical Vapor Synthesis of ZnO Nanocrystals: Optimization of Yield, Crystallinity,

    CHEMICAL VAPOR DEPOSITION, Issue 7-9 2009
    Moazzam Ali
    Abstract The experimental yield of ZnO nanocrystals decreases drastically with increasing reactor temperature in a typical chemical vapor synthesis (CVS) of ZnO nanocrystals from diethylzinc. A novel CVS set-up , a microwave plasma combined with a hot-wall zone , is described to minimize the loss of particles at higher reactor temperatures. The powder samples have been characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). It is observed that the synthesis set-up and reaction temperature have substantial influence not only on yield but also on crystallite size and crystallinity of the pure wurtzite-type ZnO nanocrystals. The lattice constants of ZnO nanocrystals increase with decreasing crystallite size. Defect densities (twin and stacking faults), as well as microstrain, decrease with increasing reactor temperature, whereas crystallinity increases. [source]

    In-Situ Preparation of Polymer-Coated Alumina Nanopowders by Chemical Vapor Synthesis

    CHEMICAL VAPOR DEPOSITION, Issue 1 2003
    M. Schallehn
    Abstract Nanocrystalline alumina particles coated with polyethylene have been prepared by a two-step chemical vapor synthesis (CVS) process using a hot-wall reactor to synthesize the nanocrystalline alumina core, and a RF plasma reactor for the subsequent polymer coating. The particle radius is about 4,nm, with the radius of the ceramic core being about 2.5,nm and the coating thickness about 1.5,nm. The powders have been characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer,Emmett,Teller (BET), small-angle neutron scattering (SANS), and high-resolution transmission electron microscopy (HRTEM). [source]