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  • Artikel: DFG Deutsche Nationallizenzen  (578)
  • 1
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Journal of Chromatography A 661 (1994), S. 143-151 
    ISSN: 0021-9673
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3484-3489 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have prepared a sintered CoSb3–FeSb2 composite where the FeSb2 particles are dispersed in the CoSb3 matrix by mechanical grinding (MG) and hot pressing, and investigated the Seebeck coefficient, electrical resistivity, and thermal conductivity in order to estimate the corresponding figure of merit. The thermal conductivity of the composite is lower than that of CoSb3. The electrical resistivity of the composite increases with increasing MG time, but it is lower than that of CoSb3 at high temperature. The decrease in the thermal conductivity and the lesser increase in the electrical resistivity are ascribed to the enhancement of phonon scattering caused by the dispersion of FeSb2 particles in the CoSb3 matrix and the low electrical resistivity of FeSb2, respectively. As a result, the composite whose molar ratio of CoSb3 to FeSb2 is 0.7:0.3 and the MG time is 25 h has a maximum figure of merit value of 6.1×10−4 K−1 at 756 K. This value is much larger than the maximum value of CoSb3 at 482 K of 3.2×10−4 K−1. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 92 (2002), S. 1391-1398 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: (Zn1−yMgy)1−xAlxO powders were synthesized by the polymerized complex method and then consolidated by spark plasma sintering apparatus. The microscopic structure and thermoelectric properties were examined comparing with the experimental results of the samples prepared by the conventional solid-state reaction method. A small amount of ZnAl2O4 spinel phase as the second phase was observed in the sintered samples with x≥0.02 by x-ray diffraction and a scanning electron microscope. The grain size of the samples prepared by the polymerized complex method is much smaller than that of the samples prepared by the conventional solid-state reaction method. The absolute values of the Seebeck coefficient and electrical resistivity decrease with increasing x up to about x=0.01, but above x=0.01 they are almost independent of x. This result indicates that the solubility limit of Al in Zn1−xAlxO is about x=0.01, which is also confirmed by 27Al nuclear magnetic resonance spectroscopy. At a fixed composition of x, the absolute values of the Seebeck coefficient and electrical resistivity for the samples prepared by the polymerized complex method are smaller than those for the samples prepared by the solid-state reaction method, which indicates that the doping of the carrier into the material can be more easily realized in the samples prepared by the polymerized complex method. The thermal conductivity decreases with increasing x, but the further suppression of the thermal conductivity was attained by the additional substitution on the Zn site by Mg. The Seebeck coefficient of (Zn1−yMgy)1−xAlxO is almost independent of Mg content y, but the electrical resistivity increases with increasing y. As a result, (Zn0.90Mg0.10)0.9975Al0.0025O shows a maximum dimensionless figure of merit of 0.10 at 1073 K. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4530-4532 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The influence of a substitution of Mn for Fe in the Sm2(Fe,Mn)17Nx alloys on the structure and the magnetic properties was studied. Sm2(Fe,Mn)17Nx alloy powders of 32–74 μm in particle size with several values of x were successively synthesized using NH3+H2 gas. It was found that the primary phase of the powders maintained the Th2Zn17-type structure in the wide range for 0〈x〈6. On the other hand, the coercivity of the powders remarkably increased for x〉3. The Sm2(Fe0.95Mn0.05)17N5 powder proved to have a coercivity of 0.62 MA/m (7.7 kOe), without a fine grinding. Microstructural analysis by transmission electron microscopy and energy-dispersive x-ray analysis revealed the powder consisted of Sm2(Fe,Mn)17N3 nanocrystalline grains of 10–30 nm in diameter surrounded by Mn-enriched amorphous phase. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4536-4538 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A new mechanical grinding (MG) process in NH3 and subsequent nitriding in N2 without a crystallization treatment was developed for synthesizing Sm2Fe17Nx powders. This process features a shorter MG time compared to conventional MG to prevent amorpharization of the alloy structure and to avoid hydrogen in the ground powders which promotes a diffusion of nitrogen atoms into their particles. The Sm2Fe17Nx powder with x=3.2 prepared by grinding for 10 h and subsequent nitriding at 723 K for 6 h showed magnetic anisotropy and its magnetic properties were Ir=1.00 T, iHc=0.61 MA m−1, and (BH)max=129 kJ m−3 (16.1 MGOe). © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2169-2172 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: This paper discusses the impact ionization rates of holes in AlxGa1−xSb near x=0.06, where resonance impact ionization is expected. Resonance impact ionization did not occur in a range of the electric field we studied. We evaluate the impact ionization of holes at the spin-split-off band theoretically, and show that our measured result is reasonable.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1190-1193 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: An x-ray spectrometer has been designed and constructed for Compton scattering measurements using 40–70 keV x-rays from an ellipsoid multipole wiggler (EMPW) installed in the accumulation ring of the National Laboratory for High Energy Physics at Tsukuba. The spectrometer has four sets of a Cauchois-type energy analyzer and an imaging plate, which are arranged on the surface of a cone and share a scattering angle of 160°. In each energy-analyzing system, to increase signal to noise ratio a set of vertical and horizontal slits are inserted between the analyzer and the imaging plate. A resolution of 0.13 a.u. in terms of electron momentum was achieved. A Compton profile of a vanadium single crystal was measured with an integrated counting rate of 400 counts/s.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A high-resolution Compton spectrometer has been installed for 29.5-keV incident x rays from a vertical wiggler inserted in the 2.5-GeV storage ring of the Photon Factory at Tsukuba. This spectrometer consists of bent-crystal monochromator, a Cauchois-type bent-crystal analyzer, and an imaging plate as a position sensitive detector. The overall momentum resolution is 0.084 a.u. for the incident x-ray energy of 29.5 keV. High-resolution Compton profile measurements on Al, a quasicrystal Al-Li-Cu, and solid and liquid phase of Li are shown to demonstrate the performance of this spectrometer.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 932-938 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A new design concept of a streak tube is conceived to obtain femtosecond temporal resolution. It is based on four factors as follows. First, in order to decrease the photoelectron transit time spread, one must investigate how high electric field is practically usable near the photocathode. It is found that the value can be increased up to ∼6 kV/mm and this is used as a design value. Second, as the other method to decrease the photoelectron transit time spread, an electromagnetic focusing method must be adopted because there is no region similar to the focusing section of an electrostatic focusing type where the electric potential is low. Third, the focusing magnetic field should be located in a limited region to obtain a very high sweep speed of ∼2×108 m/s. And fourth, in the operation, a special readjustment of the focusing magnetic field should be performed to compensate the photoelectron beam defocusing caused by the very rapid transient deflection field. Based on the above, a new streak tube has been designed, manufactured, and tested. The limiting temporal resolution of ∼400 fs has been predicted theoretically and the value less than ∼500 fs has been experimentally produced.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Recent developments of the insertion devices have made it possible to utilize intense hard x rays for precise Compton-profile measurements. A Compton profile of Si (110), which is measured using 29.5-keV synchrotron-radiation x rays, is shown as an example of a precise measurement having a momentum resolution of 0.084 a.u., the best resolution ever achieved. A promising plan is presented on magnetic electron Compton-profile measurements using circularly polarized 60-keV x rays from a newly developed multipole wiggler in the 6-GeV accumulation ring at KEK as an elliptically polarized source.
    Materialart: Digitale Medien
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