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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 55 (1990), S. 416-420 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 7853-7861 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The correlation between the resistivity of TiB2 and the chemical vapor deposition parameters and subsequent annealing temperature have been studied. The films deposited from TiCl4 and B2H6 above 600 °C are found to be nearly stoichiometric TiB2 with a resistivity of 250 μΩ cm±20%, while those deposited below 600 °C are found to contain excess boron, and exhibit a higher resistivity. The resistivity of the films is observed to be independent of thickness in the thickness range from 15 to 550 nm. After high-temperature rapid thermal annealing ((approximately-greater-than)1000 °C), the resistivity is reduced to as low as 36 μΩ cm. The grain size in annealed films increases exponentially with temperature. The conductivity and the Hall mobility of the samples increase linearly with the grain size. The activation energy of grain growth, conductivity, and Hall mobility was found to be the same, 1.6–1.7 eV. From these results, it is evident that the carrier mobility of TiB2 is dominated by grain boundary scattering. The lower limit for resistivity of chemical vapor deposited TiB2 films is expected to be attainable only after annealing at temperatures approaching 1300 °C.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 5106-5122 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Single-crystal and powder neutron diffraction, coherent neutron inelastic scattering, and Raman spectroscopy have been used to study the low temperature structure and dynamics of ammonium perchlorate. No evidence for a phase transition is found. Based on analysis of thermal motion amplitudes and inelastic neutron-scattering data for ND4ClO4 a Raman-active B3g symmetry zone-center mode at 45 cm−1 is identified as a libration. Another Raman-active mode, B1g symmetry at 33 cm−1, and a previously unobserved Au symmetry mode at 12 cm−1, are inferred to have significant librational character at q=0. Comparison of these results with earlier incoherent neutron scattering results suggests that, because of the low activation energy of ammonium ions, classical jump reorientations strongly influence ammonium-ion sublattice dynamics even to temperatures as low as 20 K. Partial dispersion curves are also presented.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 3283-3291 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rayleigh–Brillouin spectra of aqueous solutions of hydroxyl ammonium nitrate (HAN) and triethanol ammonium nitrate (TEAN) were studied at atmospheric pressure over a temperature range from 205 to 298 K. The hypersonic velocity and absorption coefficient of the phonons were calculated from the spectra as a function of temperature. The absorption due to viscosity and internal energy exchange through the relaxation mechanisms were considered. We find that both mechanisms are responsible for the absorption, but at the lower temperature, the one related to internal energy dominates. The free volume model was used to estimate the activation energy. This value is quite consistent with values calculated from the relaxation time. The effects of relaxation and the water concentration on mixtures of aqueous solutions of HAN and TEAN are also discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 55 (1990), S. 4459-4461 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 78-82 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Neutron powder diffraction has been used to obtain the thermal parameters for the deuterium atoms and to confirm the crystal structure of acetonitrile-d3 at 4 K. Inelastic neutron scattering from both isotopic species is used to determine the energies of the first and second rotational levels of the methyl group. These four levels are reasonably reproduced by a threefold potential with V3=125 meV. The activation energy derived from this potential is in agreement with that previously obtained from the temperature dependence of T1 in proton magnetic resonance measurements.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 13 (1980), S. 403-409 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The phases of ammonium nitrate, NH4NO3, doped with small amounts of NiO or CuO have been studied by X-ray and neutron diffraction at various temperatures from 80 to 423 K. NH4NO3 with metal-oxide additives, which are believed to form complexes, exists as a solid solution. Phase IV is stable down to 140 K in the NiO-doped samples and 210 K in the CuO-doped sample. The thermal expansion of this phase is extremely anisotropic, with the b axis expanding rapidly with increasing temperature while the a axis contracts slightly. At higher temperatures the doped samples transform directly from phase IV to phase II, bypassing phase III, starting at about 328 K. The structure of phase II, which is disordered, was refined in the space group P4/mbm. The structure of phase III contains hydrogen-bonded chains parallel to the b axis.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 141-144 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Crystallographic properties of depleted uranium alloys (0.75 wt% Ti) with two different heat treatments were studied by neutron powder diffraction methods. The crystal structures are essentially the same as that of pure α-uranium metal, but with somewhat different unit-cell dimensions. The super-saturated Ti impurity in the quenched sample is primarily substitutional. Diffraction lines of the quenched uranium alloy showed a clear strain broadening. The r.m.s. strain obtained from the broadening was 0.0019.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 22 (1989), S. 465-469 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The crystallite orientation distributions of three magnetically aligned samples: YBa2Cu3O6 aligned in the tetragonal phase followed by oxidation for orthorhombic conversion, orthorhombic YBa2Cu3O7, and orthorhombic HoBa2Cu3O7, were studied by neutron pole-figure measurements. Each had a fiber texture with the c axis parallel to the applied-magnetic field direction. The orientation distributions could be described quite satisfactorily with Lorentzian or March distribution functions. The sample aligned in the tetragonal phase had distinctly better alignment than that aligned in the orthorhombic phase, with FWHMs of 19.3 (3) and 37.8 (7)°, respectively. The contour lines of the pole figures showed irregularities owing to the presence of coarse grains in the samples.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 44 (1988), S. 1671-1672 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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