ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Structure and Mössbauer spectra for the Fe–Cr system: From bulk alloy to nanoparticles (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 352-361 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure and hyperfine fields of Fe1−xCrx (x=0.0236–0.803) nanoparticles (average size of 27±2 nm) are studied at room temperature by combined x-ray diffraction and Mössbauer spectroscopy techniques. They are produced by fast evaporation of bulk alloys at 3 Torr Ar pressure. The bulk alloys of any composition are shown to exhibit a bcc structure, whereas the nanoparticles demonstrate a mixture of bcc and tetragonal σ phases in the Cr range from 24.4 to 83.03 at. %. At the Cr content of 2.36 at. % the lattice constant for nanoparticles is larger than that of the bulk alloy, though the values of hyperfine fields on Fe nuclei do not differ. The Mössbauer spectrum of nanoparticles contains an oxide doublet in addition to the sextet specific to that of the bulk alloy. In both cases the width of the sextet lines is rather narrow. However, even at ∼8 at. % Cr the lines of the sextet are broadened so much that it can be decomposed by two-three components. This is explained by freezing the high-temperature ferromagnetic fcc phase regions in the bcc lattice. As the Cr content increases, the Mössbauer spectra become more complex, transforming finally into a paramagnetic singlet. A complete ferromagnetic→paramagnetic transition is observed for the bulk alloy at 68 at. % Cr and for nanoparticles at 35 at. % Cr. The results are discussed under the assumption that at high temperatures the alloys are not homogeneous and exhibit fluctuations of the composition. With decrease of temperature these fluctuations result in decomposition of the alloy into two phases for nanoparticles whereas they are frozen at the cluster level in the bulk alloys holding a macroscopic homogeneity. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1415367
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Coupled full-wave and ray-tracing numerical treatment of mode conversion in a tokamak plasma (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 911-922 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new approach for the numerical description of tokamak plasma waves in the ion cyclotron range of frequencies is discussed. It implies coupling of the full-wave and ray-tracing codes and is capable of unified treatment of waves of completely different scale and behavior. The method is applied for simulations of the electron heating scenario, based on fast wave (FW)–ion Bernstein wave (IBW) mode conversion near the ion–ion hybrid resonance in Tore Supra [B. Saoutic et al., Phys. Rev. Lett. 76, 1647 (1996)]. The two-dimensional full-wave "ALCYON" code [D. J. Gambier and A. Samain, Nucl. Fus. 25, 283 (1985)] is used to describe the global FW field pattern in the plasma volume. A small-scale-waves filter, introduced into the code, artificially damps the mode-converted power, which is further prescribed to IBW rays. Remnant small-scale fields are extracted from the global pattern to provide information necessary for IBW rays to start. Three-dimensional evolution of IBW rays is simulated by the "RAYS" ray-tracing code [Yu. Petrov, Nucl. Fus. 34, 63 (1994)], being unrestricted by finite mesh size and finite Larmor radius effects. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.873888
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    RADAR upper hybrid resonance scattering diagnostics of small-scale fluctuations and waves in tokamak plasmas : The 42nd annual meeting of the division of plasma physics of the American Physical Society and the 10th international congress on plasma physics (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 2224-2231 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The upper hybrid resonance (UHR) scattering technique possessing such merits as one-dimensional probing geometry, enhancement of cross section, and fine localization of scattering region is modified in the new diagnostics under development to achieve wave number resolution. The fluctuation wave number is estimated in the new technique from the scattering signal time delay measurements. The feasibility of the scheme is checked in the proof of principal experiment in a tokamak. The time delay of the UHR scattering signal exceeding 10 ns is observed. The small scale low frequency density fluctuations are investigated in the UHR RADAR backscattering experiment. The UHR cross-polarization scattering signal related to small scale magnetic fluctuations is observed. The lower hybrid (LH) wave propagation and both linear and nonlinear wave conversion are investigated. The small wavelength (λ≤0.02 cm) high number ion Bernstein harmonics, resulting from the linear wave conversion of the LH wave are observed in a tokamak plasma for the first time. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1358839
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Plasma current in tokamak conditions: An application of the guiding field line model (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 4095-4105 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new kinetic representation for the plasma current is examined for tokamak conditions. Within this representation, the periodic bounce motion is extracted from the guiding center motion of particles. The drift orbit of a guiding center is viewed as a closed loop stretched along the guiding field line—a field line that moves at the bounce-averaged drift rate. Because all quantities, including the distribution function, are defined not on the basis of the particle's guiding center, but rather on the basis of the guiding field line, an additional magnetization term appears, which corresponds to the wobbling deviation of the guiding center from the guiding field line. Thus, the current is decomposed into three terms: The flow of orbits as a whole, the gyro-magnetization, and bounce–wobble magnetization. The great advantage of the new model is that the zeroth-order distribution function, a nonshifted Maxwellian distribution, yields a current that satisfies the fluid equations. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1289891
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    On ferro- and antiferromagnetic ordering in ultrafine particles of Fe-rich Fe–Ni and Fe–Mn alloys (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 7001-7005 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrafine Fe–Ni (28%–32%) and Fe–Mn (30%) particles with an average size of 10–15 nm are studied by combined x-ray diffraction and Mössbauer spectroscopy techniques with the latter being applied at a temperature range from 298 to 4 K. They are produced by evaporation of bulk alloys at 3 Torr Ar pressure. From the x-ray data the ultrafine Fe–Ni (28%–32%) particles are a mixture of bcc and fcc phases, and the ultrafine Fe–Mn (30%) particles contain bcc, fcc, and hcp phases. It is shown that in the former the paramagnetic fcc phase transforms to the antiferromagnetic state with decreasing temperature from 77 down 4 K. As for the latter, the fcc phase is observed to be antiferromagnetic even at room temperature whereas the hcp phase keeps a paramagnetic state right down to 4 K. The results corroborate the Weiss hypothesis that the high temperature face-centered-cubic lattice of Fe-rich alloys can exist in two (ferro- and antiferromagnetic) spin states. The oxide contribution in the spectra is also separated. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371785
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Some specific features of fine Fe and Fe-Ni particles : The 6th joint magnetism and magnetic materials (MMM)-intermag conference (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6496-6498 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By comparing results of Mössbauer spectroscopy and x-ray diffraction investigations of ultrafine Fe and Fe-Ni particles, a formerly stated supposition on the existence of two spin states of the fcc phase in pure iron and Fe-Ni alloys has been verified. Some structural peculiarities of particles under study have been observed also. For the pure bcc-Fe particles with an average diameter of 30 and 50 nm the existence of two hyperfine fields (H1=330 kOe, H2=360 kOe) at room temperature has been found. It is supposed that H2 in the bcc phase could be considered as a remnant of a high spin state of the fcc-Fe phase at high temperature. Particles of Fe-Ni(30.3 wt %), Fe-Ni(35 wt %), and Fe-Ni(52 wt %) alloys with an average diameter ranging from 5 to 15 nm were studied also. Particles of Fe-Ni (30.3 wt %) and Fe-Ni(35 wt %) alloys with diameter of 5–8 nm had the bcc structure. A mixture of the bcc and fcc phases appeared with an increase of the particle size. At the same time only the fcc structure remained for the largest particles. The observed size structural dependences and the existence of the stable bcc phase in small particles can be explained by the martensite fcc-bcc transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358237
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Comparative study of the structure and local magnetic order in bulk and ultrafine particles of Fe–Mn (32%–35%) and Fe3Pt (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 3042-3046 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of Fe–Mn (32% and 34.65%) and Fe3Pt Invar alloys during the transition from bulk to ultrafine (3–20 nm) particles is done at room temperature by combined x-ray diffraction and Mössbauer spectroscopy techniques. The particles obtained by evaporation of foil or filings of bulk material in an Ar atmosphere at pressures from 0.16 to 50 Torr were rapidly quenched during their production. Mössbauer measurements confirmed the availability of two spin states in both Fe–Mn and Fe3Pt fcc particles like it has been observed in previous studies of fine Fe and Fe–Ni (30%–35%) particles. Various heat treatments of the Fe3Pt foil with the initial bcc structure made it possible to obtain its fcc modification in either the entirely ordered or the entirely disordered state. It was shown that the disordered fcc structure in a bulk sample could exist in two spin states (ferromagnetic and paramagnetic) whereas the ordered structure was only in a ferromagnetic state. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366142
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    The structural and the magnetic properties of the solid solutions GecFe3−cO4 (abstract) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 5666-5666 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The physicochemical properties of the compound oxide solid solutions versus the composition and the presence of defects are to be described in terms of the cluster components method.1 The binary solid solution, containing the cation with three different charge magnitudes (+2; +3; +4) is considered as the simplest system. The changes of the crystalline lattice parameter (a) and the saturation magnetic moment (σ) of the spinel solution versus the concentration of Ge are studied. We also consider that the concentration dependencies a and σ on the Ge concentration should be interpreted with regard to the defect structure and the character of the redistribution of Fe2+ on the nonequivalent positions. The conducted analysis allows to assume that the obtained solutions are defect due to the volatility of Ge. In this case the part of Fe2+ occupies the tetrapositions. As the result, σ exceeds the magnitudes obtained according to the Néel model with the C concentrations between 0 and 0.5, if Fe3O4 and GeFe3O4 are the pure components. The research of the pycnometric density agrees with the data on the defect structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342267
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Time characteristics in laser diffusion of gaseous mixtures through capillaries (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 4173-4177 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: New experimental results are reported pointing to the temporal characteristics of gas mixture flows of resonant and nonresonant molecules through metallic capillary tubes under the action of low-power cw CO2 laser radiation. While a selective laser action was always observed upon resonant molecules, a special category of nonresonant molecules is introduced whose transit through the capillary is influenced besides a pure thermal action by the vibrational energy transfer from the resonant molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343296
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Investigation of stray currents and increase of the safety of electric blasting operations (1985)
    Springer
    Power technology and engineering 19 (1985), S. 438-442 
    Details
    ISSN: 1570-1468
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Conclusions The investigations made it possible to develop recommendations on increasing safety under conditions of constructing an underground hydroelectric station which pertain both to sources of stray currents and to the shot-firing circuits: 1. Prevention and maximum possible reduction of the duration of emergency operating regimes of electric power plants; maintenance of the insulation of all elements of the electric-supply system at the level required by the power plant regulations; elimination of the extension of a dangerous potential into the zone of conducting electric blasting operations through extended metal devices; monitoring of the level of stray currents by means of special stray-current signaling instruments. 2. Use of low-sensitivity electric detonators (type ÉD-1-8-T or ÉD-1-3-T), selection of the safest arrangement and optimal configuration of the shot-firing circuit; the area covered by the wires of the SFC should be minimum, the trunk lines should be twisted together, or special cables (for example, type KRPG KhL, etc,) should be used; maintenance of the normal (not less than 5 kΩ) insulation resistance of the SFC; checking of the insulation resistance of the SFC by means of special measuring instruments. Strict observance of the requirements of the unified blasting regulations during blasting operations, the taking of measures to reduce the intensity of stray currents, and the elimination of their dangerous effect on the SFC will make it possible to considerably increase the safety of electric blasting operations during construction and to prevent premature firing of the ED.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01439559
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...