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  • 1
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Zinc sulfide (ZnS) powders have been obtained by precipitation from homogeneous solutions of various zinc salt compounds, with S2- as precipitating anion, formed by decomposition of thioacetamide. Spherical particles with a very narrow size distribution can be obtained by controlling the synthesis parameters. The particle sizes are influenced by the nature of the associated anion. For example, nanometer-sized ZnS particles are formed using acetate or acetylacetonate anions under acidic pH conditions, controlled by the addition of acetic acid. Although the nucleation is accelerated by the use of acetic acid, limited particle growth occurs because of the formation of complexes with zinc cations that lowers the concentration of free cations in the solution. Also, the complexing-attachment phenomena of the ZnS particles with acetate and acetylacetonate anions lead to the arrest of particle growth processes. The presence of complexed Zn2+ species in the acidic solution is demonstrated both theoretically, using a model based on the calculations of the solubility isotherms of the soluble species, and by Fourier-transform infrared techniques. The nanostructured ZnS particles may provide a suitable semiconductor nanocluster material for optoelectronic applications as well as a phosphor suitable for application in flat-panel display technology.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 2047-2063 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin melt crystallized spherulitic films of isotactic polypropylene have been deformed in uniaxial tension at different temperatures and examined by transmission electron microscopy. As the temperature was increased above approximately -80°C, a transition from high aspect ratio craze-like features to highly voided shear deformation zones was observed, these latter initiating both at spherulite boundaries and along the spherulite diameters perpendicular to the tensile axis. In rapidly crystallized films, the draw ratio in the deformation zones was estimated to be close to the natural draw ratio of the melt entanglement network, and was independent of test temperature in the range investigated. However, for crystallization temperatures above approximately 125°C, the mean draw ratio within the deformation zones was found to increase with crystallization temperature. It was also observed that, although the draw ratios in deformation zones in ß spherulites were similar to those in α spherulites in films containing both modifications, the former showed more homogeneous textures. This suggests that the particularly pronounced textures associated with α spherulites in polypropylene thin films are linked to their crosshatched lath-like lamellar morphology.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 485-493 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Free standing thin films of poly(ether ether ketone) crystallized in situ by heating from the glassy state have been shown to be suitable for high resolution transmission electron microscopy lattice imaging. Films mounted on coarse-mesh copper grids could also be observed in the deformed state, allowing lattice imaging of regions of strain induced crystallization at temperatures in the neighbourhood of the glass transition temperature.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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