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  • Polymer and Materials Science  (3)
  • methacrylate copolymers  (2)
  • 72.80.Ey  (1)
  • 1
    ISSN: 1432-0630
    Keywords: 72.20.−i ; 72.80.Ey ; 78.70.Gq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We report the contactless determination of the conductivity, the mobility and the carrier concentration of II–VI semiconductors by means of the technique of the partially filled waveguide at a microwave frequency of 9 GHz. The samples are CdHgTe epitaxial layers, grown on CdZnTe substrates by molecular beam epitaxy. The conductivity is determined from the transmission coefficient of the sample in the partially filled waveguide. For the analysis of the experimental data, the complex transmission coefficient is calculated by a rigorous multi-mode matching procedure. By varying the conductivity of the sample, we obtain an optimum fit of the calculated data to the experimental results. Comparison with conductivity data determined by the van der Pauw method shows that our method allows to measure the conductivity with good accuracy. The behaviour of the transmission coefficient of the sample is discussed in dependence on the layer conductivity, the layer thickness and the dielectric constant of the substrate. The calculations require to consider in detail the distribution of the electromagnetic fields in the sample region. The usual assumption of a hardly disturbed TE10 mode cannot be used in our case. By applying a magnetic field in extraordinary Voigt configuration, galvanomagnetic measurements have been carried out which yield the mobility and thus the carrier concentration. These results are also in good agreement with van der Pauw transport measurements.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 8 (1997), S. 625-627 
    ISSN: 1573-4846
    Keywords: composite materials ; sol-gel-process ; methacrylate copolymers ; dynamic-mechanical-analysis ; electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sol gel derived composite materials were prepared from methacryloxypropyltrimethoxysilane (MPTS) and tetraethyleneoxidedimethacrylate (TEGDMA). The amount of MPTS in the composites was varied from 0 to 50 mole%. MPTS was prehydrolyzed at room temperature with 0,1 mole/l HCl/H2O. After complete removal of solvent calculated amounts of TEGDMA were added to the reaction mixture of the prehydrolyzed MPTS. Thermically initiated free radical copolymerization of the methacrylate endgroups was performed in the resulting mixture under nitrogen atmosphere using azobisisobutyronitril (AIBN) as initiator. The composites were investigated by high resolution transmission electronmicroscopy in order to investigate the morphology. The thermomechanical properties as storage, loss modulus, tan δ as well as the glass transition temperature (T g ) of the composites were estimated by dynamic mechanical thermal analysis (DMTA).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 8 (1997), S. 625-627 
    ISSN: 1573-4846
    Keywords: composite materials ; sol-gel-process ; methacrylate copolymers ; dynamic-mechanical-analysis ; electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sol gel derived composite materials were prepared from methacryloxypropyltrimethoxysilane (MPTS) and tetraethyleneoxidedimethacrylate (TEGDMA). The amount of MPTS in the composites was varied from 0 to 50 mole%. MPTS was prehydrolyzed at room temperature with 0,1 mole/l HCl/H2O. After complete removal of solvent calculated amounts of TEGDMA were added to the reaction mixture of the prehydrolyzed MPTS. Thermically initiated free radical copolymerization of the methacrylate endgroups was performed in the resulting mixture under nitrogen atmosphere using azobisisobutyronitril (AIBN) as initiator. The composites were investigated by high resolution transmission electronmicroscopy in order to investigate the morphology. The thermomechanical properties as storage, loss modulus, tan-as well as the glass transition temperature (T g ) of the composites were estimated by dynamic mechanical thermal analysis (DMTA).
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 64 (1992), S. 786-787 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 24 (1996), S. 79-85 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Very high laser intensities (1014-1015 W cm-2) have been used to photoionize both sputtered and gaseous samples. The cross-sectional spatial intensity distributions of a 35 ps, 532 nm laser beam have been analyzed by direct optical imaging and show near-diffraction limited and near-Gaussian profiles at and near focus. Experimental results from sputtered atoms and gaseous atoms and molecules demonstrate that the high laser beam quality combined with the high power density leads both to the saturation of photoionization of species with very different ionization potentials and to a sharply defined ionization volume with well-characterized spatial distributions. It is possible not only to make a quantitative surface composition analysis under high sensitivity conditions using high-intensity multiphoton ionization but also to drive the relative sensitivity factors towards unity. This work demonstrates the feasibility of performing quantitative surface and material analysis under high sensitivity conditions by using very high-intensity non-resonant multiphoton ionization.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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