bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anisotropic Penetration of Positrons in Monocrystalline RbBr
Authors: Behnisch R. , Bell F. , Sizmann R. 
Published: July 2007

AbstractAn investigation was made of the dependence of K‐line‐X‐ray yield by positrons with an energy spectrum from 120 to 480 keV (average energy 220 keV) on the angle between the positron beam (divergence ± 0.6°) and 〈100〉 of a RbBr single crystal. There is a nearly 90% reduction of the yield with a HWHM of nearly 2° in the case of bombarding parallel to 〈100〉. In particular, a comparison is given between this positron effect and the behaviour of X‐ray excitation by channelled protons.
On the Dynamical Behaviour of Excitons in CdS Single Crystals. II. Correlation between Intrinsic Excitonic Absorption and Photoconductivity
Authors: Voigt J. , Ost E. 
Published: July 2007

AbstractAn investigation is made of the excitation spectra of photoconductivity of CdS single crystals in the region of the fundamental absorption edge from 77°K to room temperature. The results are compared with those of excitonic absorption measurements. On the basis of conclusions about the dynamical behaviour of excitons, equally drawn from absorption, emission, and photoconductivity measurements, a model is proposed of the photoconductivity in the region of exciton transitions, which explains the correlation between the exciton absorption and photoconductivity. This model involves that the diffusion length of the excitons don't exceed that of the ambipolar electron–hole pair diffusion.
Unstable Directions of Shockley Partial Dislocations
Authors: Clarebrough L. M. , Head A. K. 
Published: July 2007

AbstractSharp bends are observed in Shockley partial dislocations in a Cu + 15.6 at% Al alloy. Computations using the method of Head [1] suggest that these bends arise from unstable directions for Shockley partial dislocations in elastically anisotropic f.c.c. crystals.
Self‐Diffusion Measurements in Gold Single Crystals between 286 and 412°C
Authors: Rupp W. , Ermert U. , Sizmann R. 
Published: July 2007

AbstractBy means of an electrochemical peeling technique the self‐diffusion coefficients in 99.99% gold single crystals were determined at 285.9, 299.6, 321.0, 349.7, and 411.7°C. Assuming a linear dependence of log D on 1/T the result is in this temperature range . There is no evidence for short circuiting interferences in the range of the evaluated diffusion profile depths of < 3000 Å.
Electron–Phonon Interaction of Crystal Electrons in High Electric Fields
Authors: Hacker K. 
Published: July 2007

AbstractThe electron–phonon interaction in high electric fields is investigated. The calculation of the electron lifetime shows that Wannier–Stark levels may exist. It is furthermore shown that there is a field dependent phonon production. It can possibly be measured by Raman scattering and serve to demonstrate the existence of the Wannier–Stark levels.
Calcul des courbes de dispersion de phonons des oxydes de magnesium, de calcium, et de strontium
Authors: Mon J. P. 
Published: July 2007

AbstractNous avons calculé les courbes de dispersion de phonons de MgO, CaO et SrO en utantilis le “breathing‐shell‐Model”. La comparasion des courbes obtenues montre qu'il se produit un plus grand nombre de croisements de branches dans MgO que dans CaO ou SrO, ce qui doit se traduire par la présence d'un plus grand nombre de points critiques singuliers dans le spectre de MgO.
Spontaneous Magnetization of Iron‐Rich Iron–Germanium and Iron–Silicon Alloys at 298°K
Authors: Arajs S. 
Published: July 2007

AbstractThe mass magnetization of 19 iron‐rich binary iron alloys containing different amounts of silicon and germanium has been studied as a function of magnetic field at 298°K using a vibrating sample magnetometer. The mass spontaneous magnetizations have been determined from these data by means of the Belov‐Arrott‐Kouvel method. The curve of the spontaneous magnetization versus composition for iron–silicon alloys lies below the simple dilution curve while that for the iron–germanium system lies above it. The results of this investigation are compared with those of the previous studies on the saturation magnetization of the above‐mentioned solid solutions.
Long Wavelength Optical Lattice Vibration of Selenium–Tellurium Mixed Crystals
Authors: Geick R. , Hassler J. 
Published: July 2007

AbstractThe reflectivity of selenium–tellurium mixed crystals is studied in the far infrared spectral region. The eigenfrequencies, oscillator strengths etc. of the strongly infrared active lattice vibrations are deduced from the reflection spectra by means of a classical oscillator model. The two modes which give rise to a pronounced reststrahlen band show “one mode behaviour”. Moreover, an impurity mode is observed existing in the mixed crystals only. By means of a random‐element‐isodisplacement model (REI) adapted to the trigonal structure of these crystals, the eigenfrequencies and oscillator strengths are calculated as a function of composition and, at least, qualitative agreement with the experimental data and also some insight into the nature of the impurity mode is achieved.
Residual Resistivities of Binary Iron Alloys
Authors: Arajs S. , Schwerer F. C. , Fisher R. M. 
Published: July 2007

AbstractElectrical resistivities of iron‐rich binary alloys containing seventeen different solutes have been measured at 4.2°K and the resistivity increment per atom percent solute tabulated. Apparent departures from Matthiessen's rule at room temperature have also been determined. The non‐transition elements cause considerably larger increases in the resistivity at 4.2°K and smaller deviations from Matthiessen's rule than do the transition elements. Cobalt, nickel, and tin are exceptions to this classification. This behavior is discussed in terms of electron screening and resonating s‐ and p‐orbitals in the electron bands of the iron matrix. A correlation of the observations with solute size and valence effects is also presented.
Mössbauer Study of Oxidized Iron Silicate Minerals
Authors: Häggström L. , Wäppling R. , Annersten H. 
Published: July 2007

AbstractBiotites and Ca‐amphiboles have been studied. Certain changes in composition of the Ca‐amphiboles could be correlated to changes in the Mössbauer parameters. The ordering of iron in biotites is discussed. The ferrous‐ferric iron ratio could be determined in all the silicates.
The Contribution of Three‐Body Overlap Forces to the Dynamical Matrix of Alkali Halides
Authors: Verma M. P. , Singh R. K. 
Published: July 2007

AbstractThe so‐called S2‐approximation in the Heitler‐London theory of ionic crystals as developed by Löwdin gives rise to a three‐body contribution in the cohesive energy. The present paper describes a method of deriving the coupling coefficients for the three‐body potential from expressions given by Lundqvist. These coupling coefficients involve certain lattice sums which can be evaluated in terms of incomplete gamma functions by a method due to Born and Bradburn. A new lattice dynamical model of ionic solids has been suggested which is obtained by injecting the three‐body coupling coefficients into the shell model of Woods et al. in a way that preserves symmetry in the wave vector space. Preliminary calculations show that this model can prove superior to other current models.
Magnetisierung in der Umgebung unmagnetischer Einschlüsse in Ferromagnetika. III. Wechselwirkung eines kugelförmigen unmagnetischen Einschlusses mit einer Blochwand
Authors: Schröder K. 
Published: July 2007

AbstractDie Wechselwirkungsenergie eines kugelförmigen Hohlraums mit einer Blochwand besteht aus einem Fremdkörper‐ und einem Streufeldanteil. Der Streufeldanteil wird ohne Berücksichtigung der Auslenkung der Magnetisierung durch innere Felder berechnet. Gegenüber früheren Abschätzungen ergeben sich erhebliche Abweichungen. Das Ergebnis wird auf die Theorie der Koerzitivfeldstärke angewandt.
Electron Absorption in UO2
Authors: Blank H. 
Published: July 2007

AbstractSpecimens of UO2 and U4O9 have been observed by transmission electron microscopy at electron energies of 100, 500, and 1000 kV. Approximate values of the absorption parameters μ0 and tg/τg for UO2 have been deduced from bright field pictures of crystal wedges in two beam cases with s > 0. The results are compared with data of other substances given in the literature. The stability of the oxygen sublattice in UO2 and U4O9 with respect to 1 MeV electrons is discussed.
Current Instability in Germanium due to Excitation of the Recombination Waves
Authors: Karpova I. V. , Kalashnikov S. G. , Konstantinov O. V. , Perel V. I. , Tsarenkov G. V. 
Published: July 2007

AbstractSpontaneous current oscillations were observed in n‐type germanium containing manganese. The latter was compensated with antimony so that the upper level Ec −0.37 eV was only partly filled with electrons. The spontaneous current oscillations were observed at room temperature or near it, and for an electric field strength of several tenths of V/cm. The oscillation frequency was in the range of 0.1 to 1 MHz. The relative amplitude of the current oscillations reached 50 to 90%. As was shown by the probe measurements, the instability was a bulk phenomenon and contact effects were not essential. It was proved that this phenomenon might be interpreted in terms of excitation of the recombination waves predicted in [1].
Anisotropy of the Hall Effect of n‐Ge in Strong Non‐Quantizing Magnetic Fields
Authors: Babich V. M. , Baranskii P. I. , Dakhovskii I. V. , Samoilovich A. G. 
Published: July 2007

AbstractThe magnetic field dependence of the Hall coefficient, RH = ‖(H), has been investigated theoretically and experimentally in n‐Ge at 77°K on samples with different orientations (H ‖ [100] and H ‖ [110], I ‖ [110] in both cases) within wide interval of concentration. Calculations of the RH = f(H) dependence were carried out on the basis of the anisotropic scattering theory up to H = 106 Oe and measurements were made in the whole interval of magnetic fields (H ≦ 105 Oe) up to quantizing. Attention is attracted to a necessity of refusal from formal application of H → ∞ for the analysis of the field dependence RH = f(H), since the Boltzmann equation validity has an upper limit of H‐values, corresponding to quantizing effects set up. Taking into account this circumstance in the concrete case of n‐Ge both the results of calculations and the experimental data lead to conclusions that a) throughout the interval of classically strong H (up to 105 Oe at 77°K) the Hall coefficient remains anisotropic; b) when the impurity scattering contribution increases, then beginning with some values of this contribution, the saturation of RH = f(H) throughout the whole classically strong field range cannot be achieved.
Fundamental Reflectivity Spectrum of CdxHg1−xTe Crystals from 1.5 to 4 eV
Authors: Gałązka R. R. , Kisiel A. 
Published: July 2007

AbstractReflectivity measurements of solid solutions of CdxHg1−xTe for x from 0.02 to 0.74 and for x = 0 and x = 1 have been performed in the range from 1.5 to 4 eV at the temperature of 315°K. Two maxima in the reflection spectrum were observed. They are interpreted as connected to the transitions E1 and E1 + Δ1 at the Λ‐point of the Brillouin zone. The values of E1, E1 + Δ1, and Δ1 are nonlinear functions of the composition x. The change of the peak position E1 with the composition between x = 0.00 and 0.10 is nonmonotonous. The reflection spectra for HgTe and CdTe are in a good agreement with previously reported ones.
Wechselwirkungskräfte zwischen einer Flußlinie und einer parallelen Versetzung
Authors: Kammerer U. 
Published: July 2007

AbstractAusgehend von den in einer früheren Arbeit entwickelten Berechnungsmethoden für das auf dem Volumeffekt beruhende Eigenspannungsfeld einer isolierten geraden Flußlinie und für das auf dem ΔC‐Effekt beruhende Eigenspannungsfeld einer Flußlinie in der Nachbarschaft einer parallelen Versetzung, wird die Wechselwirkungskraft zwischen einer Flußlinie und einer parallelen Versetzung in Störungstheorie 1. Ordnung (entsprechend 1. Potenzen in der Änderung des spezifischen Volumens und der elastischen Konstanten innerhalb der supraleitenden Phase) berechnet. Für beliebigen Versetzungscharakter und beliebige Wahl der zwölf die Kopplung im elastisch isotropen Fall beschreibenden Materialkonstanten läßt sich aus dem mitgeteilten numerischen Ergebnissen für \documentclass{article}\pagestyle{empty}\begin{document}$\chi = 1/\sqrt 2 $\end{document}, 1, 2 und 5 der Kraftverlauf zwischen Flußlinie und paralleler Versetzung ermitteln.
Uniaxial Stress Effects on Parity‐forbidden Transitions in NaCl:Cu+ and KCl:Ag+
Authors: Dultz W. 
Published: July 2007

AbstractThe temperature dependence of the stress‐induced dichroism in the UV absorption bands of NaCl:Cu+ and KCl:Ag+ is investigated. The experiments are explained by a frequency splitting of the IR active resonance mode and an off‐centre displacement of the defect in the excited state. The value of the quadratic electron—lattice interaction is determined.
On the UV Absorption of Heavy Metal Ions in Alkali Halide Crystals I. Experimental Results
Authors: Fussgaenger K. 
Published: July 2007

AbstractUV absorption spectra of Ag+, Cu+, and Tl+ centres in alkali halide crystals are measured between 5 and 300°K in order to determine the electronic fine structure of the bands as well as the magnitude and temperature dependence of the UV dipole strength. The structure and temperature dependence of the spectra are interpreted in terms of electron—phonon interaction and off‐centre effects.
Investigation of the Structure of Ferromagnetic Films by Means of the Differential Susceptibility
Authors: Kempter K. , Hoffmann H. 
Published: July 2007

AbstractThe differential susceptibility of thin polycrystalline iron–nickel‐films has been measured. From the results the structure constant, S, could be determined. The experiments gave the same field dependence for the susceptibility as was expected by former calculations. The values for S, evaluated from the experiment, can be explained quantitatively by the mean crystallite diameter, the magnetocrystalline anisotropy, the magnetostriction constants, and the intrinsic stresses, if one uses the Doyle‐Finnegan formula for the calculation. The measurements show quantitatively the existence of the intrinsic demagnetizing field, which has been predicted by micromagnetic calculations and which contributes to the whole effective field.
Charged 90° Walls in Iron platelets
Authors: Gemperle R. , Kaczér J. 
Published: July 2007

AbstractThin platelets of iron single‐crystals containing 90° Bloch walls charged by an application of an external field or mechanical stress have been investigated using the magnetic colloid technique. It is found that these walls are rotated in such a manner that their area increases thereby decreasing the charge density. In very thin platelets the area of the walls increases by more than one order of magnitude.
O− Centers as Strong Phonon Scatterers in KCl and KBr Crystals
Authors: Kurz G. 
Published: July 2007

AbstractThe thermal conductivity of pure and hydroxide doped KCl and KBr crystals and its change upon OH− dissociation was measured. The temperature range covered is 1.8 to 22°K. The dissociation of OH− ions into O− and U2 centers causes a marked reduction of the thermal conductivity curve below 10°K. The scattering cross section of the U2 centers is shown to be small, thus the strong phonon scattering can be attributed to the O− centers alone. The O− ion is suggested to occupy an off‐center equilibrium position in the anion vacancy, the accompanying tunnel splitting thus giving rise to a low lying resonance.
ESR of Ni2+ in AgCl and Isotope Effect in Crystal Field
Authors: Höhne M. , Stasiw M. , Watterich A. 
Published: July 2007

AbstractESR measurements are made on Ni‐doped AgCl at low temperatures. As in the case of AgBr:Ni, already investigated, a line with isotropic g‐value is found, due to isolated Ni2+. Moreover an angular dependent spectrum with nearly [100]‐axial symmetry is observed, which is attributed to complexes of Ni2+ with a silver vacancy. Contrary to the results on AgBr:Ni a structure of the anisotropic spectrum is observed in a small angular range, which may be explained only by the presence of very small orthorhombic perturbations. It is shown, that these orthorhombic perturbations of different quantities result from the variant distributions of both the isotopes 35Cl and 37Cl in the plane perpendicular to the axis of the centre.
Lineare Kontinuumstheorie bewegter Versetzungen
Authors: Stenzel G. 
Published: July 2007

AbstractMit einer mechanischen Lagrange‐Funktion wird eine Integralgleichung hergeleitet, die die Bewegung einer Versetzung in einem elastischen Kontinuum beschreibt. In der Näherung tiefer Frequenzen kann diese Gleichung in ein äquivalentes Variationsproblem umgewandelt werden, das nur die Koordinaten der Versetzung enthält. Dieser Ausdruck läßt sich als Lagrange‐Funktion eines verbesserten Saitenmodells deuten, in welchem auch die nichtlokale Wechselwirkung berücksichtigt ist.
ESR of Neutron‐Irradiated BaF2 Crystals
Authors: Kazumata Y. 
Published: July 2007

AbstractNeutron‐irradiated BaF2 was studied by ESR. The thermal stability of the F‐centre formed by neutron‐irradiation was investigated. Three types of V‐centres (VK, VF, and V111) were also observed. The spin Hamiltonian parameters of the three V‐centres were calculated from experimental data and the thermal stability of the centres were studied by a pulse annealing method. A model of the new type of V‐centre (F2− molecule‐ion in [111] direction) is proposed.
A Calculation of the Wavefunction and Isotropic Hyperfine Structure Constants of the U2‐centre in NaCl and KCl
Authors: Sammel B. 
Published: July 2007

AbstractThe wavefunction of the U2‐centre is determined by a variational procedure taking into account the charge distribution of the nearest neighbour ions. All wavefunctions concerned are mutually orthogonalized using a combined Schmidt‐Löwdin procedure. The influence of the 2‐centre exchange integral and of a possible distortion of the crystal near the centre is discussed. The isotropic hyperfine and superhyperfine structure constants are calculated.
Effect of the Polariton–Phonon Coupling on the Spatial Dispersion
Authors: Hizhnyakov V. V. 
Published: July 2007

AbstractA formula is obtained for the transverse dielectric constant ϵt(ω, k) in the region of exciton transition which appears to be correct for an arbitrary intensity of the polariton—phonon coupling. The renormalization of polaritons caused by this coupling and the influence of the renormalization on the damping constant of ϵt(ω, k) are examined.
Electrical Pinch in Intrinsic Elastically Bent Germanium
Authors: Boiko I. I. , Zhadko I. P. , Romanov V. A. 
Published: July 2007

AbstractTheoretical and experimental investigations of the conductivity of elastically bent intrinsic Ge are performed. An high asymmetry of the current—voltage characteristic is predicted and observed in plates with a high velocity of surface recombination. It is connected with the deviation of the spatial distribution of carriers for two opposite directions of current, flowing through the crystal. It is shown that a negative differential resistance in thin crystals may arise at great electrical fields. Current oscillations connected with the Joule heating of the specimen are observed.
Zum Peierls‐Modell bewegter Versetzungen
Authors: Stenzel G. 
Published: July 2007

AbstractZur Beschreibung der Versetzungsbewegung unter dem Einfluß äußerer Kräfte wird ein leicht modifiziertes Peierls‐Modell vorgeschlagen. Die Bewegungsgleichungen lassen sich in ein Variationsproblem umformen. Es enthält nur die Relativverschiebungen der beiden atomistisch behandelten Gitterebenen.
Magnetic Domain Wall Motion at Low Temperatures
Authors: Bostanjoglo O. , Fichtner H. 
Published: July 2007

AbstractThe magnetic reversal in polycrystalline iron foils was investigated by means of Lorentz microscopy at 4 to 300 °K no usual Barkhausen jumps exist. The wall motion of cross‐tie walls consists of small‐size (55 to 3000 å) Bloch line jumps, formation of bordering domains of the order 1 × 1 μm2, and their reversal by rotation. Above a minimum field these processes proceed at constant field. This aftereffect in constant field is influenced by crystal defects.
On the Shift of the Reflectivity of Polarized Light with Applied Uniaxial stress in Silicon
Authors: Leonhardt H. 
Published: July 2007

AbstractThe shift of the reflectivity maximum of polarized light found in silicon at 3.4 eV with applied uniaxial strain in the [1, 0, 0] direction is described by a simple model within the framework of the pseudopotential method. The shift results mainly from contributions close to the centre of the Brillouin zone and is a consequence of the rapid decrease of the pseudopotential for large K‐values.
Interpretation of the Electric Field Effect on the Ground State Splitting of Mn++ Ions in NaCl
Authors: Dreybrodt W. , Silber D. 
Published: July 2007

AbstractThe cS5/2 ground state splitting of Mn++ centres with an associated nearest neighbour cation vacancy in NaCl is calculated from a point ion model of the centre by using various theoretically proposed mechanisms. It is shown that the main contribution to the ground state splitting parameters results from a relativistic effect. The electric field induced changes of the ground state splitting are calculated from this mechanism. There are two contributions: 1. The combined effect of the external field and internal odd fields. 2. The change of the internal even fields from field induced relaxations of the centre. The results agree in sign and order of magnitude with the experimental data.
Investigations on Evaporated Films of Bismuth Oxide II. Determination of Type of Conductivity and Photoconductivity Measurements on Doped and Undoped Layers
Authors: Gobrecht H. , Seeck S. , Bergt H. ‐E. , Märtens A. , Kossmann K. 
Published: July 2007

AbstractThe type of conductivity of pure Bi2O3 layers is determined by the change of conductivity under the influence of chemisorbed oxygen. The spectral photoconductive sensitivity is measured on undoped and doped Bi2O3 layers within the range of 0.8 to 3.5 eV. The time constant of the photoelectric effect of pure Bi2O3 layers can be reduced by photoadsorption of oxygen. A sulfur or selenium doping of the layers causes a shift of the wavelength limit towards the near infra‐red. The time constant is greatly reduced. The doped layers are suitable for vidicon use.
Positive and Negative Infrared Photoconductivity of CdS Single Crystals near the Double Injection Threshold
Authors: Vateva E. 
Published: July 2007

AbstractAn increase or a decrease of the dark conductivity of CdS is observed by irradiation with infrared light at threshold voltages of the appearance of negative resistance due to double carrier injection. The experimental results show that the positive as well as the negative infrared photoconductivity is due to release of holes of the slow recombination centres. For an explanation of the appearance and the sign of the observed photoconductivity a model is proposed which is fit to the peculiarities of CdS and the presence of injected electrons and holes.
A Modified Formulation of Lattice Dynamics
Authors: Achar B. N. , Barsch G. R. 
Published: July 2007

AbstractA modified formulation of lattice dynamics based on two‐dimensional Fourier‐transforms of the coupling parameters is presented. This approach will be useful for the study of twodimensional defects, surfaces, and layer structures. Subsequent Fourier‐transform in the third dimension recovers the conventional formulation of lattice dynamics. The method is applied to the eigenfrequencies of rocksalt in the approximation of the point ion model and is shown to reproduce Kellermann's results.