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End date: 2009 × Start date: 2008 × Type: Text × WGL Institute: INM ×

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Now showing 1 - 10 of 19
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    Transparent conductive oxides for coating applications
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2009) Quilitz, Mario; Oliveira, Peter W. de; Heusing, Sabine; Veith, Michael
    Transparent, conductive oxides (TCOs) applied as coatings find multiple applications in various areas such as flat panel display setups, as electrodes in touch-screen panels, electrochromic devices, solar cells and in architectural applications for example as IR reflectors. The favored material in the class of TCOs is still ITO - Sn-doped In2O3 - due to its unique combination of high transparency and electrical conductivity. Though already very good, the potential of the ITO coatings with regard to their conductivity leaves some space for future improvements. Also ITO as a material has some serious drawbacks, such as limited availability and high costs. this work presents some stratgies to overcome these obstacles. One way to enhance the conductivities of alternative materials is to use carbon nanotubes as a dopant. This strategy was tested for ATO (Antimony-doped Tin Oxide), Titan dioxide and AZO (Aluminium-doped Zinc oxide). The results for these materials are presented. In coatings of ITO on glass or polymeric foils usually silica-based binders are used. They have the disadvantage to reduce the contact between the highly conducting grains and thus reduce overall conductivity in the composite. The matrix between the nanoparticles can be improved by several measures. Experiments with relevance in this direction are discussed. A third strategy aims at the reduction of costs in the process of ITO fabrication. Here one way to go is to use an electrochemical synthesis method. Results of the line of development are presented. Other strategies comprise the suitable processing of materials with a lower intrinsic conductivity or the search for materials with high intrinsic conductivity close to that of ITO. Exmples are presented and discussed.
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    Large area production of optical coatings and devices by the sol-gel process
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2009) Oliveira, Peter; Quilitz, Mario; Heusing, Sabine; Lin, Hechun; Veith, Michael
    [no abstract available]
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    One-dimensional oxide nanostructures: growth, applications and devices
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2008) Barth, Sven; Mathur, Sanjay; Hernandez-Ramireza, Francisco; Romano-Rodrigueza, Albert
    One dimensional (1D) inorganic materials are gaining high attention due to their structural stability and unique structural fatures. Among them, oxides are widely studied due to their well established application potential and mechanical as well as chemical stability. We have developed a generic approach for size-selective and site-specific growth of oxide nanowires by combination of a catalyst assisted growth mechanism and a molecular precursor approach, which is a viable alternative to other gas phase and solution procedures and produces well-defined (morphology and composition) materials.
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    Kelvin probe force microscopy of charged indentation-induced dislocation structures in KBr
    (Saarbrücken : Leibniz-Institut für neue Materialien, 2009) Egberts, Philip; Bennewitz, Roland
    The incipient stages of plasticity in KBr single crystals have been examined in ultrahigh vacuum by means of Atomic Force Microscopy and Kelvin Probe Force Microscopy (KPFM). Conducting diamond-coated tips have been used to both indent the crystals and image the resulting plastic deformation. KPFM reveals that edge dislocations intersecting the surface carry a negative charge similar to kinks in surface steps, while screw dislocations show no contrast. Weak topographic features extending in <110> direction from the indentation are identified by atomic-resolution imaging to be pairs of edge dislocations of opposite sign, separated by a distance similar to the indenter radius. They indicate the glide of two parallel {110} planes perpendicular to the surface, a process that allows for a slice of KBr to be pushed away from the indentation site.
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    The analysis of arabidopsis nicotianamine synthase mutants reveals functions for nicotianamine in seed iron loading and iron deficiency responses
    (Rockville, MD : American Society of Plant Biologists, 2009) Fink-Straube, Claudia; Klatte, Marco; Schuler, Mara; Wirtz, Markus; Hell, Rüdiger; Bauer, Petra
    Nicotianamine chelates and transports micronutrient metal ions in plants. It has been speculated that nicotianamine is involved in seed loading with micronutrients. A tomato (Solanum lycopersicum) mutant (chloronerva) and a tobacco (Nicotiana tabacum) transgenic line have been utilized to analyze the effects of nicotianamine loss. These mutants showed early leaf chlorosis and had sterile flowers. Arabidopsis (Arabidopsis thaliana) has four NICOTIANAMINE SYNTHASE (NAS) genes. We constructed two quadruple nas mutants: one had full loss of NAS function, was sterile, and showed a chloronerva-like phenotype (nas4x-2); another mutant, with intermediate phenotype (nas4x-1), developed chlorotic leaves, which became severe upon transition from the vegetative to the reproductive phase and upon iron (Fe) deficiency. Residual nicotianamine levels were sufficient to sustain the life cycle. Therefore, the nas4x-1 mutant enabled us to study late nicotianamine functions. This mutant had no detectable nicotianamine in rosette leaves of the reproductive stage but low nicotianamine levels in vegetative rosette leaves and seeds. Fe accumulated in the rosette leaves, while less Fe was present in flowers and seeds. Leaves, roots, and flowers showed symptoms of Fe deficiency, whereas leaves also showed signs of sufficient Fe supply, as revealed by molecular-physiological analysis. The mutant was not able to fully mobilize Fe to sustain Fe supply of flowers and seeds in the normal way. Thus, nicotianamine is needed for correct supply of seeds with Fe. These results are fundamental for plant manipulation approaches to modify Fe homeostasis regulation through alterations of NAS genes.
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    The scale-up of material microstructuring: a perspective
    (Saarbrücken : Leibniz-Institut für Neue Materialien, 2009) Kraus, Tobias
    [no abstract available]
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    Research on the synthesis and applicability of surface modified nanoscaled metal oxide particles as curing catalyseres for UV-print-colours and lacquers
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2009) Becker-Willinger, Carsten; Schmitz-Stöwe, Sabine; Bentz, Dirk
    In the BMBF joint research project - NANOCURE - New Curing Methods for Print-Colours, Glues and Lacquers (prom. ref. : 13N9115) - a new class of nanoscaled photo initiators for radical polymerization processes in the printing industry is to be investigated. A possible mechanism for the reaction of TiO2 with acrylates, which is already described in literature is presented. Different methods of manufacturing TiO2 nanoparticles in the lower nanometric size range and their subsequent processing are described, the method is of special interest as it may lead to a possible integrated production process of UV-printing inks. The TEM analysis shows the homogeneous arrangement of TiO2 nanoparticles in an acrylic matrix, which is a necessary requirement for successful polymerization process. IR-spectroscopy is used to show the effect of TiO2-nanoparticles as UV photocatalytic polymerization initiators.
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    Mechanisms of bonding effected by nanoparticles in zirconia coatings applied by spraying of suspensions
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2008) Adam, Jens; Aslan, Mesut; Drumm, Robert; Veith, Michael
    Zirconia coatings consisting of a mixture of coarse and fine grained zirconia powders prepared by spraying of suspensions and subsequent thermal treatment at limited temperatures (up to 500°C) are poor in adherence and in intrinsic mechanical strength. We have shown elsewhere that mechanical properties of these coatings can be improved clearly by adding a small amount of nanoscaled zirconia. Here, the structural and the chemical development of this coating material and of the nanoparticles is examined to gain information about the underlying bonding mechanisms. The applied temperature is relatively low in comparison to the usual onset temperature of accelerated sintering. Nevertheless, the results show that diffusion controlled material transport mechanisms play their role in bonding. The condensation of surface OH groups may participate in bonding, too. These first results confirm the potential of nanoparticles to act as inorganic binder. Additional research effort to clarify the underlying mechanisms in detail is of interest. For the practical side, it can be concluded that the resulting effect of mechanical consolidation of ceramic structures at relatively low temperatures enables new ceramic applications, for example a new type of ceramic coatings on metallic substrates.
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    Wet chemical syntheses of Ag-nanoparticles
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2008) Moh, Karsten; Schumacher, Sarah
    [no abstract available]
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    Translucent UV light absorbant coatings for wood
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2009) Ullrich, Alfred; Reinhard, Bernd; Wittmar, Matthias
    Efficient protection of fast growing domestic woods against the effects of weathering and UV irradiation is of increased significance to obtain improved dimensional stability and durability comparable to tropical wood. To advance the properties of those woods, a combined treatment process was developed. First, samples of pine sapwood were impregnated by project partners in the University of Göttingen to improve the dimensional stability and to avoid fungal infection of the wood, then a coating containig zinc oxide nanoparticles was applied on the impregnated wood samples at INM. Due to the UV light absorption of zinc oxide nanoparticles, the coated wood substrates are distinguished by enhanced colour stability. Together with the impregnation the coating prevents wood from deterioration by UV-irradiation and changing climates while retaining optical appearance. The water-repellent properties of the coatings interfered with the impregnation and reduced the ingress of water. This resulted in a stabilising reduction of the swelling and shrinking and avoided the formation of cracks in both wood and coating. The improved characteristics were demonstrated by artificial weathering. A prototype of an impregnated and coated window has been manufactured and is currently exposed to outdoor weathering.