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  • 61.12Dw  (2)
  • DSC  (2)
  • Springer  (4)
  • American Chemical Society (ACS)
  • Berlin: Deutsches Institut für Wirtschaftsforschung (DIW)
Collection
Publisher
  • Springer  (4)
  • American Chemical Society (ACS)
  • Berlin: Deutsches Institut für Wirtschaftsforschung (DIW)
Years
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 54 (1992), S. 19-21 
    ISSN: 1432-0630
    Keywords: 61.12Dw ; 72.10 ; 78.50G
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The formation of silicon oxide precipitates from Czochralski grown silicon depends on the time and temperature of the heat treatment as well as on the initial content of interstitially dissolved oxygen. Samples containing between 5×1017 Oi/cm3 and 13×1017 Oi/cm3 have been heated at 750° C for 96 h. SiO2 precipitates of various shape and size have been obtained and investigated by means of small angle neutron scattering (SANS) in the Q-range 0.05 Å−1〈Q〈0.2 Å−1. The obtained SANS patterns reveal a typical anisotropy of their intensity distribution, which splits into a central peak at Q〈0.1 Å−1 due to the shape of the individual particles and a number of weak intensities for large Q-values, originating from a correlation between defects, possibly between the precipitates. While these correlation peaks in the SANS patterns are seen best for rather low values of about (5–7)×1017 Oi/cm3 oxygen content, the central peak anisotropy is most pronounced for higher values of ca 10×1017 Oi/cm3. The integrated intensity of the central peak increases with increasing initial oxygen content. For comparison, untreated samples of the same initial oxygen content do not reveal any anisotropic SAN scattering or a broadened central peak beam.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0630
    Keywords: 61.12Dw ; 72.10 ; 78.50G
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Czochralski grown silicon crystals contain interstitially dissolved oxygen which diffuses on heating to form precipitates of silica. We have examined these precipitates by small angle neutron scattering (SANS) in the Q-range 0.05 Å−1〈Q〈0.4 Å−1. The obtained SANS patterns reveal pronounced anisotropic intensity distributions which resemble the symmetry of the host crystal. The SANS spectra show an anisotropic central peak at Q〈0.1 Å−1 due to the single particle shape and a number of weak intensities for larger Q-values. These weak side maxima are considered correlation peaks or quasi-elastic interference peaks. They show, however, an unexpected and distinct temperature dependence: with decreasing temperature below values of 220 K their intensity is lost slowly, but reversibly. At T = 50 K only the central peak from the single-particle scattering remains unchanged. Upon heating, the correlation peaks regain their former value of intensity and Q-position without any evidence of thermal hysteresis.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 277-287 
    ISSN: 1572-8943
    Keywords: DSC ; limit of detection ; polymorphic transitions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Anhand von sehr kleinen Signalen von spontanen polymorphen übergängen bei CsCl, K2Cr2O7 und Na2SO4 wird ein Verfahren zur Bestimmung der Nachweisgrenze von DSC-Geräten beschrieben. Es wird gezeigt, wie derartige Signale gut aufgelöst in DSC-Diagrammen von Pulverproben erhalten werden können. Um sie vom Rauschen der Basislinie zu unterscheiden, sollten sie eine Höhe von mindestens dem Doppelten der Basislinienbreite aufweisen. Für das angewendete Gerät beträgt die entsprechende geringste Wärmemenge, d.h. die Nachweisgrenze 0.1 mJ.
    Notes: Abstract A procedure is described to determine the limit of detection of DSC instruments by using tiny signals from spontaneous polymorphic transitions of CsCl, K2Cr2O7 and Na2SO4. It is shown how such signals can be found well-resolved in DSC diagrams of powder samples. To distinguish them from the baseline noise they should exhibit a height at least twice that of the baseline width. For the instrument employed the corresponding smallest amount of heat, i.e., the limit of detection, was found to be 0.1 mJ.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 145-155 
    ISSN: 1572-8943
    Keywords: acrylates ; DMA ; DSC ; epoxides ; radiation curing ; structure-property relationship ; TG ; thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermo-oxidative and thermo-mechanical stabilities of radiation-cured acrylates and epoxides were examined by TG, DMA and DSC. The polymeric trifunctional acrylates PETIA, TMPTA and THEIC displayed the highest temperatures of onset of degradation. The high crosslinking density of the films resulted in an almost temperature-independent complex E-modulus, as measured by DMA. With increasing degree of ethoxylation or propoxylation of the monomers, decreases in thermal stability and strength were found. For difunctional polymeric acrylates and epoxides, the glass transition temperature was measured. The average degree of curing of UV-cured epoxy films can be determined from the temperature of the maximum in the loss modulus (E″max.
    Type of Medium: Electronic Resource
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