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
    Suppression of superparamagnetism in surface-oxidized nanocrystals (1990)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 12 (1990), S. 35-43 
    Details
    ISSN: 0392-6737
    Keywords: Diamagnetism and paramagnetism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Si sono preparati nanocristalli di Fe (particelle con una dimensione di alcuni nanometri) per mezzo del metodo della condensazione di gas inerti con conseguente ossidazione. La misura media delle particelle nel fine strato di ossido è stata determinata intorno ai 30 Å. Si sono studiati i campioni attraverso la spettroscopia di Mössbauer a varie temperature. In questi esempi il supermagnetismo sembra essere soppresso. Inoltre si è osservata una diminuzione del campo medio iperfino nello strato di ossido. L'anisotropia dell'interfaccia tra ossido di Fe e Fe è proposta come causa di questo fenomeno.
    Abstract: Резюме Используя метод конденсации в инертном газе с последующим окислением, приготовляутся нанокристаллы железа (частицы с размерами порядка нанометров). Средние размеры частиц в тонком слое окисла составляют около 30 Å. Полученные образцы исследуются с помощью Мессбаузровской спектроскопии при различных температурах. Наблюдается двух-ступенчатое уменьшение среднего сверхтонного поля в слоях окисла. Предполагается, что анизотропия границы раздела между окислом железа и железом является ответственной за это явление.
    Notes: Summary Fe nanocrystals (particles with a size of some nanometers) were prepared by the inert-gas condensation method with subsequent oxidization. The average size of the particles in the thin oxide layer was determined to be about 30 Å. The samples were studied by Mössbauer spectroscopy at various temperatures. Superparamagnetism seems to be suppressed in these samples. Furthermore, a two-stage decrease of the average hyperfine field was observed in the oxide layer. The Fe oxide-Fe interface anisotropy is proposed to be responsible for this phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02453024
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A model for the high-T c superconductivity based on electron hopping (1987)
    Springer
    Applied physics 44 (1987), S. 101-104 
    Details
    ISSN: 1432-0630
    Keywords: 74.00
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A model is proposed based on electron hopping between octahedral Cu2+ and Cu3+ ions. Exchange interaction is assumed to be an electron-exciton one. Ground-state excitons are formed by freeze-in of the hopping process. The model is able to explain the main phenomena observed in the new high-T c superconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00626407
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Symplectic quantization of open strings in constant background B-field (2003)
    Springer
    The European physical journal 29 (2003), S. 447-451 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The symplectic quantization (Faddeev-Jackiw) method is reviewed briefly, and then it is applied to the open strings in the D-brane background with a non-vanishing constant B-field. We shall work in the discrete version, and the reduced phase space is obtained directly by solving the mixed boundary conditions. The non-commutativity of coordinates along the D-brane is reproduced. Some ambiguities in the previous papers could be avoided by this method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2003-01233-2
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Phase relation in the system La1−xBaxFeO3−y (0⩽x⩽0.70) (1992)
    Springer
    Journal of materials science 27 (1992), S. 4361-4364 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Samples of the system La1−xBaxFeO3−y, (0⩽x⩽0.70) have been synthesized and investigated by means of X-ray diffraction and Mössbauer effect. Two different phases, i.e. a barium-poor orthorhombic perovskite phase and a barium-rich cubic perovskite phase, were found to exist in the system. The phase relation at room temperature is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541567
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Study of the similarity of structural surroundings of Fe3+ ions in some oxide glasses by Mössbauer spectroscopy (1986)
    Springer
    Hyperfine interactions 27 (1986), S. 409-412 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A study of Fe3+ environments in alkali silicate glasses has been performed. The Mössbauer parameters indicate Fe in octahedral as well as in tetrahedral surroundings. The broad linewidth of the Mössbauer subspectra indicates a distribution of the hyperfine parameters due to local distortions. Using a distribution fitting program we obtained information about the distortions of octahedral and tetrahedral Fe ion surroundings from the distribution of the electric field gradient (EFG).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02354793
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Mixed hyperfine interactions and defect structure in magnesiowüstite Fe−Mg−O (1992)
    Springer
    Hyperfine interactions 68 (1992), S. 283-286 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An analysis of the 4.2 K spectra of FexO (x∼0.91) and (Fe0.4Mg0.6)xO is presented in which it is considered that because of the large electric field gradient at Fe2+ defect sites, the spectra cannot be described by Lorentzian sextets. It is assumed that the magnetic hyperfine field vector is oriented at random in the coordinate system defined by the EFG main axis, and that the EFG coordinate system is also distributed randomly. The simplifying assumption of the asymmetry parameter η=0 allows an analytical formula to be used to describe the complex spectra. Distributions of both magnetic hyperfine field and quadrupole interaction were progressively refined resulting in reasonable fits to the spectra with the main features being well reproduced. The magnetic hyperfine field distribution is rather broad with several features present while distinct values were obtained in the distribution of quadrupole interactions. These latter values are considered to correspond to the defect configurations around the Fe2+ sites. The distribution of hyperfine fields is considered to reflect the varying strengths of superexchange due to the high defect concentration as well as the effects of magnetic relaxation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02396491
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Influence of solvent on the superparamagnetic relaxation of nanocrystalline Fe3O4 in ferrofluids (1992)
    Springer
    Hyperfine interactions 70 (1992), S. 1129-1132 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mössbauer spectra for 5 nm Fe3O4 nanocrystallites coated with different surfactants were measured and show a significant influence on superparamagnetic relaxation with and without the solvent in ferrofluids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02397528
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Magnetic behaviour and site occupation of YFe12-x V x (x=2,3,4) (1992)
    Springer
    Hyperfine interactions 68 (1992), S. 299-302 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effects of vanadium substitution on the iron magnetism in YFe12-x V x compounds (x∼2–4) have been studied by57Fe Mössbauer spectroscopy. The preference of vanadium atoms for the 8i site of these ThMn12-structure type compounds is confirmed. The rapid collapse of the iron sublattice magnetization with increasing vanadium concentration is analysed in terms of the ‘magnetic valence’ model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02396495
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Magnetic relaxation in nanocrystalline iron-oxides (1990)
    Springer
    Hyperfine interactions 54 (1990), S. 571-575 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nanocrystalline Fe oxides are compacted solids of fine particles. By compacting interfaces are formed between adjacent particles. Since collective magnetic relaxation and superparamagnetism depend on the anisotropic energy, it is expected that the existence of interfaces and related interface anisotropy will change the relaxation behavior of nanocrystalline Fe oxides. Measurements on nanocrystalline α-Fe2O3 and γ-Fe2O3 have shown that the exchange interaction in the interfaces is more effective in suppressing superparamagnetic relaxation upon compacting than the dipole interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02396092
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Magnetism of nanocrystalline materials (1990)
    Springer
    Hyperfine interactions 54 (1990), S. 591-597 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nanocrystalline solids are materials consisting of small crystallites (typically 1–10 nanometers). These materials have a high proportion of atoms located in the interfacial regions between the crystallites. Therefore their magnetic properties are strongly determined by the interfaces. In this work we present Mössbauer studies carried out on various nanocrystalline materials. Beneath the normal crystalline component the Mössbauer spectra clearly indicate the existence of an component with modified magnetic properties which corresponds to the interfaces in this type of material. For nanocrystalline α-Fe an enhancement of the hyperfine field was observed in the interfacial component at low temperatures, whereas a decrease was found for nanocrystalline Ni.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02396095
    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...