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  • 1
    Electronic Resource
    Electronic Resource
    Topological analyses of cuprite, Cu2O, using high-energy synchrotron-radiation data (2000)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 575-584 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Topological analyses were performed on room-temperature and low-temperature high-energy synchrotron-radiation data from cuprite, Cu2O, using both single-exponential and analytical functions in the multipole model. Differences between the refinements of the data sets turned out to be small and the data were found to be well suited for the analyses and for evaluations of further properties, e.g. the electrostatic potential and the Laplacian. The ionic character of the the copper–oxygen bond was impressively underlined by the results. On the `empty' tetrahedral sites, minima of the charge density were always found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767300010254
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  • 2
    Electronic Resource
    Electronic Resource
    TaSi2-Si composites as wide-bandpass optical elements for synchrotron radiation : The 9th National conference on synchrotron radiation instrumentation (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 3355-3355 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The wide matrix rocking curves of the in situ eutectic composite TaSi2-Si make it attractive as a wide-bandpass monochromator for synchrotron radiation. Wafers with Si[111], Si[110], or Si[100] orientation were studied to determine the origin of the wide rocking curves. The high degree of preferred orientation of the TaSi2 rods relative to the Si matrix was examined using synchrotron Laue patterns and the TaSi2 [100], TaSi2 [003], and TaSi2 [102] reflections. Double and triple axis diffractometry were used to show that the large widths were due to strain and mosaic and not long-range bending; copper radiation (for some double axis results) and 120 and 160 keV synchrotron radiation were used. At 8 keV, rocking curve widths were about twenty times broader than those from perfect Si, and peak reflectivities approached 20%. Rocking curves from Si[333] and Si[444] (120 and 160 keV, respectively) had identical profiles and reflectivities of about 25%. The triple axis results show compressive strains in the Si matrix along Si[111] (i.e., parallel to the rods) and dilational strains orthogonal to the rods. These results confirm the promise of TaSi2-Si as a wide-bandpass optical element for synchrotron radiation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147373
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  • 3
    Electronic Resource
    Electronic Resource
    Magnetic-field-dependent plasma composition of a pulsed aluminum arc in an oxygen ambient (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 150-152 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A variety of plasma-based deposition techniques utilize magnetic fields to affect the degree of ionization as well as for focusing and guiding of plasma beams. Here we use time-of-flight charge-to-mass spectrometry to describe the effect of a magnetic field on the plasma composition of a pulsed Al plasma stream in an ambient containing intentionally introduced oxygen as well as for high vacuum conditions typical residual gas. The plasma composition evolution was found to be strongly dependent on the magnetic field strength and can be understood by invoking two electron impact ionization routes: ionization of the intentionally introduced gas as well as ionization of the residual gas. These results are characteristic of plasma-based techniques where magnetic fields are employed in a high-vacuum ambient. In effect, the impurity incorporation during reactive thin-film growth pertains to the present findings. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1339847
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  • 4
    Electronic Resource
    Electronic Resource
    Role of hydrogen for the elastic properties of alumina thin films (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1144-1146 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe the role of the presence of hydrogen on the elastic properties of AlxOyHz (0.32≤x≤0.4; 0.54≤y≤0.6; 3×10−4≤z≤0.14) films. The films were deposited by reactive magnetron sputtering in an Ar/O2/H2O discharge and were studied by Rutherford backscattering spectrometry, nuclear resonance analysis, selected area electron diffraction, as well as nanoindentation. As the hydrogen concentration is increased from 0.03% to 13.9% the measured elastic modulus value is reduced by approximately 53%. The measured elastic modulus is in excellent agreement with our electronic structure calculations. The large scattering in the reported values of the elastic properties of amorphous alumina thin films can readily be understood by hydrogen incorporation during synthesis. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1448389
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  • 5
    Electronic Resource
    Electronic Resource
    Magnetic-field-dependent plasma composition of a pulsed arc in a high-vacuum ambient (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1531-1533 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of a magnetic field on the plasma composition of a pulsed Au plasma stream in a high-vacuum ambient is described. The plasma was formed with a pulsed vacuum-arc-plasma source, and the time-resolved plasma composition was measured with time-of-flight charge-to-mass spectrometry. Plasma impurities due to ionization of nonmetallic species (H+, O+, and N+) were found to be below the detection limit in the absence of a magnetic field. However, in the presence of a magnetic field (0.4 T), the contribution of ionized nonmetal species to the plasma composition was up to 0.22 atomic ratio. These results are characteristic of plasma-based techniques where magnetic fields are employed in a high-vacuum ambient. In effect, the impurity incorporation during thin-film growth pertains to the present findings. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126086
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  • 6
    Electronic Resource
    Electronic Resource
    Temporal development of the plasma composition of a pulsed aluminum plasma stream in the presence of oxygen (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 612-614 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe the temporal development of the plasma composition of pulsed aluminum plasma streams at various oxygen pressures. The plasma was formed with a vacuum arc plasma source and the time resolved plasma composition was measured with time-of-flight charge-to-mass spectrometry. The temporal development of the plasma composition as well as the Al average ion charge state was found to be a strong function of the oxygen pressure. Oxygen and hydrogen concentrations of up to 0.36 and 0.32, respectively, were found in the first 50 μs of the pulse at oxygen pressures of ≥5×10−5 Torr. The average charge state of aluminum ions was found to vary from +1.2 to +2.5 depending on the oxygen pressure and the time elapsed after ignition of the arc. These results are of fundamental importance for the understanding of the evolution of the composition (through the plasma composition) and microstructure (through the Al ion flux energy) of alumina thin films produced by pulsed, reactive aluminum plasmas. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124457
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  • 7
    Electronic Resource
    Electronic Resource
    On the effect of hydrogen incorporation in strontium titanate layers grown by high vacuum magnetron sputtering (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3476-3478 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hydrogen incorporation in strontium titanate thin films grown in a high vacuum environment by rf magnetron sputtering on MgO(001) substrates was investigated by nuclear resonance analysis. The amount of hydrogen in the films is strongly affected by the growth temperature. Films deposited at or below 200 °C have a close-to-amorphous microstructure, are oxygen rich and exhibit hydrogen incorporation up to 0.08 (atomic ratio). As the growth temperature is increased to ≥250 °C, crystalline growth of stoichiometric SrTiO3 is obtained, with a hydrogen content of 0.006. The results provide evidence that hydrogen incorporation is decisive for the composition as well as the microstructure evolution of the layers. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125301
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  • 8
    Electronic Resource
    Electronic Resource
    Hydrogen uptake in alumina thin films synthesized from an aluminum plasma stream in an oxygen ambient (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 200-202 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe the hydrogen uptake during the synthesis of alumina films from H2O present in the high vacuum gas background. The hydrogen concentration in the films was determined by the 1H(15N,αγ)12C nuclear resonance reaction. Furthermore, we show the presence of hydrogen ions in the plasma stream by time-of-flight mass spectrometry. The hydrogen content increased in both the film and the plasma stream, as the oxygen partial pressure was increased. On the basis of these measurements and thermodynamic considerations, we suggest that an aluminum oxide hydroxide compound is formed, both on the cathode surface as well as in the film. The large scatter in the data reported in the literature for refractive index and chemical stability of alumina thin films can be explained on the basis of the suggested aluminum oxide hydroxide formation. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123292
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  • 9
    Electronic Resource
    Electronic Resource
    Accurate structure-factor measurements using high-energy synchrotron radiation: a test on cuprite, Cu2O (2000)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 33 (2000), S. 156-167 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Using high-energy synchrotron radiation, structure factors were measured on the triple-axis diffractometer at the HASYLAB beamline BW5. A data set for cuprite, Cu2O, was recorded, and the excellent data quality [internal consistency Rint(F2) = 0.0055] allowed full multipole refinements using the program VALRAY. Extinction was still significant, but small. Using data measured at 75, 100, 125 and 150 keV photon energies, it was possible to determine and separate extinction prior to the refinements. After evaluation and comparison of extinction-affected and extinction-free data, significant differences in the electron densities were found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889899012790
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  • 10
    Electronic Resource
    Electronic Resource
    Diffraction of 100 to 200 keV X-rays from an Si1−xGex gradient crystal: comparison with results from dynamical theory (1999)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 855-863 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In a large Czochralski-grown Si1−xGex (0.02 \leq x \leq 0.07) gradient crystal, diffraction patterns have been measured in symmetrical Laue geometry using synchrotron radiation in the energy range 100–200 keV. The experimental data are in very good agreement with the results from geometrical optics theory for distorted crystals, if the creation of new wavefields for strain gradients larger than a critical value is taken into account. In this sense, the crystal behaves like an ideal gradient crystal. If the normal absorption is disregarded, for reflection 111 and 100 keV energy, the full width at half-maximum values and the peak reflectivities of the diffraction patterns range from 14.6′′ and 97%, respectively, to 70.9′′ and 74%, respectively, for a variation in the Ge concentration from 3.5 to 5.3 at.%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010876739900313X
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