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  • Electronic Resource  (5)
  • precursor  (2)
  • sol-gel method  (2)
  • 25.85 Ge  (1)
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  • Electronic Resource  (5)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inorganic and organometallic polymers and materials 2 (1992), S. 143-149 
    ISSN: 1572-8870
    Keywords: Methyl(triisocyanato)silane ; ammonolysis ; polysilazane ; precursor ; silicon nitride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis and properties of polymethylsilazanes were investigated. Controlled ammonolysis of methyl(triisocyanato)silane (MTIS) at the molar ratios NH3/MTIS=4 and 6 gave polymethylsilazanes3 and4, which were soluble in tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO) but insoluble when isolated as powders. The concentrated polymer solution showed spinnability and film formation. Thermogravimetric analysis of3 and4 showed weight losses of 67 and 16%, respectively. Species4 may be a precursor for silicon/carbon/nitrogen ceramics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 16 (1999), S. 227-234 
    ISSN: 1573-4846
    Keywords: polysilsesquioxane ; precursor ; pyrolysis ; silicon oxycarbide ; ceramics ; films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The sol-gel reactions of methyl- and vinyltrimethoxysilane under controlled conditions provided the corresponding polysilsesquioxanes and flexible thin films on further condensation of the precursors. Silicon oxycarbides containing a large amount of free carbon 58 mol% and 90 mol% were obtained in high yields 90 wt% on pyrolyzing the precursors of polymethyl-and polyvinylsilsesquioxane at 1400°C under N2 atmosphere, respectively. Moreover, pyrolytic polycondensation of polyvinylsilsesquioxane was found to give the silicon oxycarbide ceramic films without deformations and cracks. The composition and properties of films were investigated.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-4846
    Keywords: sol-gel method ; silica film ; surface morphology ; porous ; low reflective glass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Silica coating films with various surface morphologies, such as flat, porous (with deep pores), concave-convex (with hills and valleys), and convex (with hills on flat plane) structure were prepared from a mixture of two kinds of sols derived from polymerized tetraethoxy-silane (TEOS) and methyltriethoxysilane (MTES). Different surface morphologies were obtained by varying the molar ratio r = MTES/TEOS of the coating solution. The surface was flat for r less than 2.5, porous for 2.5 ≤ r 〈 5, concave-convex for 5 ≤ r 〈 7.5, convex for 7.5 ≤ r 〈 13, and again flat for r larger than 13. For 2.5 ≤ r 〈 5, the apparent refractive index of the silica film with porous morphology was decreased to 1.23 by selecting the solvent and by controlling the relative humidity of the coating atmosphere and the heat treatment temperature. Coating of glass with silica films of low refractive index of 1.23 led to the low reflective glasses with visible light reflectance Rvis of less than 0.2%.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 323 (1986), S. 437-449 
    ISSN: 1434-601X
    Keywords: 25.70 Gh ; 25.85 Ge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A generalized diffusion equation is propounded to follow the time evolution of an excited nucleus towards fission including along the particle decay. This theoretical model is built in order to try to analyse the anomalous behaviour of particle emission observed in many experimental data for heavy-ion induced reactions. Some calculations for the systems194Hg,170Yb and248Cf are presented. A possible extension of this generalized formalism is suggested to deal more consistently with the experimental data.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1049-1056 
    ISSN: 0887-624X
    Keywords: tetraacetoxysilane ; boron tri-n-butoxide ; sol-gel method ; condensation ; SiO2 - B2O3 gel fibers ; borosilicates ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of SiO2-B2O3 gel fibers and oxides was investigated by the sol-gel method using tetraacetoxysilane (TAS) and boron tri-n-butoxide (BTB). Low molecular weight borosiloxanes (BS) were formed by the reaction of TAS with BTB in THF. Partial alkoxylation and hydrolysis of BS followed by further condensation of the resulting polymer (PBS) solutions led to the formation of highly polymerized polyborosiloxanes (HPBS) with good spinnability. Gel fibers were obtained by dry spinning of HPBS. The compositions of PBS and gels were not consistent with that in feed. Heat treatment of the gels, however, provided SiO2-B2O3 oxides with compositions almost compatible with those of the gels. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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