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  • 1
    Electronic Resource
    Electronic Resource
    Thermo-luminescence induced by gamma irradiation in sol-gel prepared zirconia–silica materials (2000)
    Springer
    Materials research innovations 4 (2000), S. 32-35 
    Details
    ISSN: 1433-075X
    Keywords: Key words Thermoluminesence ; Gamma irradiation ; Zirconia–silica ; Sol-gel ; Dosimeter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Zirconia–silica materials prepared by the sol-gel method at different compositions were gamma irradiated with a dosage of 40 Krads for different irradiation periods. The thermoluminescent (TL) emission was studied as a function of the zirconia for temperatures from 100 to 300 °C. Pure zirconia produces a strong TL signal, followed by 50% zirconia sample, while pure silica and the 5% zirconia sample show a weak TL signal. This means that there exists a self-inhibited process possible due, on the one hand to the segregation effects of both components, and on the other to the stabilization of either tetragonal or monoclinic zirconia phases. This effect opens the possibility to control the TL signal in a wide range of dosages allowing to use this system as a wide range dosimeter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100190000064
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation of Magnesia-Silica Oxides: Effect of Mg/Si Ratio and Sulfate on Acidity (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 321-325 
    Details
    ISSN: 1573-4846
    Keywords: magnesia-silica mixed oxides ; sol-gel magnesia-silica ; magnesia-silica acidity ; sulfated magnesia-silica ; isopropanol decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mg-Si binary oxides were prepared by the sol-gel method, using magnesium diethoxide and tetraethoxysilane as starting materials. Mg-Si mixed oxides were prepared at pH3 and 9 at nominal concentrations of 1.3, 4.0, and 6.7 mole% MgO. Density and strength of the acid sites were determined by pyridine thermal programmed desorption. Comparable Lewis acidity was found in pH3 and 9 preparations. However, when the samples were sulfated with sulfuric acid, strong Bronsted acidity was developed, reaching a maximum at 6.7 mole% MgO. The strong acidity of sulfated samples was corroborated using the isopropanol decomposition reaction as catalytic test. Similar conversions are obtained at 100°C on sulfated samples, whereas 260°C are required for non-sulfated ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026487018502
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Preparation of magnesia-silica oxides: Effect of Mg/Si ratio and sulfate on acidity (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 321-325 
    Details
    ISSN: 1573-4846
    Keywords: magnesia-silica mixed oxides ; sol-gel magnesia-silica ; magnesia-silica acidity ; sulfated magnesiasilica ; isopropanol decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mg−Si binary oxides were prepared by the sol-gel method, using magnesium diethoxide and tetraethoxysilane as starting materials. Mg−Si mixed oxides were prepared at pH3 and 9 at nominal concentrations of 1.3, 4.0, and 6.7 mole% MgO. Density and strength of the acid sites were determined by pyridine thermal programmed desorption. Comparable Lewis acidity was found in pH3 and 9 preparations. However, when the samples were sulfated with sulfuric acid, strong Bronsted acidity was developed, reaching a maximum at 6.7 mole% MgO. The strong acidity of sulfated samples was corroborated using the isopropanol decomposition reaction as catalytic test. Similar conversions are obtained at 100°C on sulfated samples, whereas 260°C are required for non-sulfated ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436859
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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