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  • Artikel: DFG Deutsche Nationallizenzen  (3)
  • Polymer and Materials Science  (3)
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  • Artikel: DFG Deutsche Nationallizenzen  (3)
Materialart
Erscheinungszeitraum
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  • 1
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 263-277 
    ISSN: 0887-6266
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Rutherford backscattering spectrometry with a 2.1-meV He2+ion beam is used to measure the diffusion of iodine into polyamic acid and polyimide films. The iodine diffusion coefficient D decreases from its initial value of about 2X10-13cm2/s in polyamic acid to approximately 1.4 × 10-15cm2/s in partially cured polyimide, but then increases to a value of nearly 1.5 × 10-14 cm2/s in fully cured polyimide. This dramatic increase in D cannot be attributed to the “in-plane” biaxial orientation of the polyimide molecules since indential D's were found with isotropic specimens. Microvoids less than 2 nm in size caused by water and carbon dioxide formation during imidization may, however, give rise to the observed behavior. The results demonstrate that Rutherford backscattering spectrometry with its excellent depth resolution (better than 30 nm) and good sensitivity (50 ppm iodine can be detected) is very useful for measuring the diffusion of slowly diffusing species in glassy polymers.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 30 (1996), S. 165-174 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Ion beam technology may be applied in a straightforward fashion to the analysis and modification of biomaterials. For analytical purposes, characterization using megaelectron-volt He2+ ions provides a standardless, nondestructive means for accurately quantifying the composition of material surfaces and the thickness of thin films. In this study, three complementary ion backscattering techniques were utilized to characterize hydroxyapatite (HA) films: Rutherford backscattering spectrometry (RBS) can determine composition and amounts of elements heavier than He; forward recoil elastic spectrometry (FRES) can determine hydrogen content; resonance-enhanced RBS can quantify small amounts of light elements, e.g. carbon, by choosing a particular incident beam energy resulting in excitation of the light element nucleus. At this resonance energy, the scattering cross section greatly increases, improving elemental sensitivity. Sol-gel chemistry was used to synthesize HA films by spin coating and annealing in a rapid thermal processor. Using these techniques, the chemical composition of unfired films was Ca1.63O5.4H1.8C0.24P with a thickness of 3.01 × 10 18 atoms/cm2 and after firing at 800°C as Ca1.66O4.0H0.26C0.09P with a thickness of 2.11 × 1018 atoms/cm2. This compares favorably to stoichiometric HA, which has a composition of Ca1.67O4.33H0.33P. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 309-316 
    ISSN: 0142-2421
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The quantification of oxygen and carbon in high-temperature (Tc) superconducting oxide thin films was made by employing elastic resonance in He backscattering analysis. A method combining the oxygen resonance technique and channeling was presented for measuring the nature of the oxygen disorder near the surface and the interface in a YBCO superconducting film grown on an MgO substrate. The oxygen resonance technique was used to quantify the oxygen profiling in the metal/YBCO contacts, showing that Zr and Nb act as sinks to oxygen from YBCO films and are oxidized in the forms Zr/ZrO2/YBCO/MgO and Nb0.2/YBCO/MgO after annealing in a vacuum at 350°C. We combined the carbon and oxygen resonances to determine the carbon contamination and oxygen concentration changes on the YBCO surface after coating and baking the photoresist. Residual carbon on the surface and a thin layer of oxygen depletion near the YBCO surface have been observed. The residual carbon in Bi2Sr2CaCu2O8 films made by the decomposition of metallo-organic precursors was quantified using carbon resonance.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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