bluuebunny/crossref_metadata_2025_split huggingface dataset:
Étude des propriétés électriques des structures AlAl2O3–métal
Authors: Barriac C. , Pinard P. , Davoine F. 
Published: July 2007

AbstractL'interprétation théorique du phénomène de résistance négative présenté par des structures AlAl2O3–M, basée sur l'existence d'une charge d'espace ionique positive au voisinage de la cathode et l'émission, à partir de celle‐ci, d'un courant électronique par effet tunnel, permet de déterminer l'influence des divers facteurs et les variations du courant émis. Les résultats expérimentaux obtenus sont en parfait accord avec les prévisions théoriques, et prouvent qu'il est possible de caractériser la résistance négative par deux coefficients dépendant de la nature de l'oxyde et de celle de la contre‐électrode.
Experimental Evidence of Plane Wave Rocking Curve Oscillations
Authors: Lefeld‐Sosnowska M. , Malgrange C. 
Published: July 2007

AbstractA double crystal spectrometer is used to obtain a nearly planar incident wave on a thin silicon crystal. A theoretical study of the experimental arrangement has been made and it is shown that the same oscillations should occur in the rocking curves as predicted by the dynamical theory for an incident plane wave. The oscillations have been observed using crystals of several thicknesses and several wavelengths. The position of the fringes are in very good agreement with theory and their contrast is quite good.
Slip line Studies of the Deformation of Copper–12 at% Aluminium Crystals in Stage I
Authors: Charsley P. , Desvaux M. P. E. 
Published: July 2007

AbstractThe deformation in tension during stage I, of Cu–12 at% Al crystals, has been studied by observing the development of slip lines with the use of a new replica technique. The deformation is macroscopically inhomogeneous and in the less deformed regions consists of clusters of lines which widen asymmetrically as deformation proceeds. It is suggested that cross‐slip does not play a significant part in the widening of the slip clusters. The variation with local strain of slip line growth and initiation has been investigated quantitatively.
The Influence of Heat Conductivities of He Baths on the Decay Functions In paramagnetic Relaxation
Authors: Kalbfleisch H. 
Published: July 2007

AbstractThe structure of the decay functions in paramagnetic relaxation is found to differ depending on whether they are measured in normalfluid or superfluid 4He. Therefore the concept of a phonon bottleneck is extended to the case of different heat conductivities of the cooling baths. The various measured decay functions can be explained in this way.
Paramagnetic Resonance of γ‐Irradiated N2H6SO4 and N2D6SO4 Single Crystals
Authors: Barbur I. 
Published: July 2007

AbstractAn ESR study was made of defects produced by γ‐irradiation in hydrazonium sulphate (N2H6SO4 and N2D6SO4). The analysis of the experimental data shows that N2H and N2D defects are formed. The mechanism of the appearance of these defects is a breakage of N–H and N–D bonds, respectively. Some remarks about the character of the singly occupied orbital are made.
On the Dependence of Photocurrents on the Excitation Strength
Authors: Stöckmann F. 
Published: July 2007

AbstractFrequently the relation between the electron concentration n and the excitation density G in a photoconductor can be exactly or approximately described by a power law n ∼ Gv. General and clear conditions for the exponent v can be derived provided the recombination of free carriers runs mainly through one channel and in the neutrality condition one group of positive and one of negative charge carriers dominate. The method is described in detail for a general model and the results are discussed.
Solution of the Micromagnetic Equations of Superconductors
Authors: Kronmüller H. , Seeger A. 
Published: July 2007

AbstractFor the solution of the micromagnetic equations of superconductors a method is developed which allows the determination of the elastic stresses from a stress function tensor. It is shown that the elastic strains present in a superconductor have the following sources: 1. Spontaneous volume dilatations. 2. Dielastic effects. 3. Effects of the non‐linear elasticity theory. The interaction energy of the elastic strains of a superconductor with stress active lattice defects is determined. The general theory is applied to the discussion of the discussion of the elastic strains due to a planar S‐N‐wall.
Étude des lacunes dans le cadmium
Authors: Hillairet J. , Martinet B. , Schumacher D. 
Published: July 2007

AbstractOn étudie les lacunes thermiques à l'équilibre dans le cadmium au moyen de mesures de résistance électrique sur un échantillon polycristallin. L'augmentation de résistivité déterminée par rapport à l'extrapolation de la loi de variation de la résistivité à basse température conduit à une énergie de formation comprise entre 0,36 et 0,39 eV, et à une concentration d'équilibre au point de fusion de l'ordre de 3 × 10−3. Ces valeurs sont discutées et comparées, en l'absence de résultats de trempe, aux valeurs correspondantes obtenues par d'autres méthodes d'équilibre.
Electron Paramagnetic Resonance of Mn2+ at the Three Sites of Yttrium Aluminium Garnet
Authors: Hodges J. A. , Dormann J. L. , Makram H. 
Published: July 2007

AbstractElectron paramagnetic resonance measurements have been made at 17.4 GHz at room and liquid helium temperatures of divalent manganese substituted into the three sites of yttrium aluminium garnet (YAlG). The relative intensities of the tetrahedral, octahedral, and dodecahedral spectra were respectively 3:2:30. Data at liquid helium temperatures in units of 10−4 cm−1 are for tetrahedral site: gz = 2.001, B = −170.6, B = 0.062, Az = −69.1; for octahedral site: gz = 2.001, B = −139.3, B = −0.088, Az = −82.3; for dodecahedral site: gz = gy = 2.001, B = −102.2, B22 = −167.8, B = −0.006, (B + B) = 0.11, Az = −85.1, Ay = −85.9. The second order zero field splittings were compared to the various existing crystal field models using the local crystalline fields at the three sites obtained by summing up the contributions of the point monopoles to convergence. Poor agreement was obtained.
Crystal‐Field Splitting of Levels and X‐Ray Spectra of Transition Metal Monoxides
Authors: Menshikov A. Z. , Brytov I. A. , Kurmaev E. Z. 
Published: July 2007

AbstractThe crystal‐field splitting of the ground state of a transition metal ion in transition metal monoxides is calculated for the case of cubic symmetry. An investigation is made of the X‐ray emission bands of metal and oxygen ions in the monoxides. The observed and calculated splittings of the levels are in good agreement.
Rotational Structure of Vibronic Absorption and Luminescence Spectra of NO Impurity Molecules in Potassium Halide Crystals
Authors: Avarmaa R. , Rebane L. 
Published: July 2007

AbstractThe rotational structure of the pure‐electronic (near 4000 Å) and other zero‐phonon lines associated with v1 and v2 modes is observed in the vibronic spectra of NO ions in KCl and KBr crystals at liquid helium temperature. Three components in the (0, 0) group of the absorption spectrum of KCl‐NO have the intervals 7 and 10 cm−1, the resonant (0, 0) group in emission consists of two components. In the KBr host some components show additional splitting. The rotation of NO in KCl about the top axis a is found to be somewhat hindered in the ground state and nearly free in the excited electronic state. Some emission occurs from thermal nonequilibrium rotational states which gives evidence for rather slow rotation‐phonon relaxation. Several groups of the absorption spectra exhibit rotational perturbations which are suggested to be caused by Coriolis interaction between the vibrations v′1(A1) and v′3(B1).
Crystal Field The ory and Optical Absorption of Cobalt and Nickel Boracites
Authors: Pisarev R. V. , Druzhinin V. V. , Prochorova S. D. , Nesterova N. X. , Andreeva G. T. 
Published: July 2007

AbstractIn the boracite structure the local symmetry of paramagnetic ions is characterized by a strong tetragonal distortion of the cubic component of the crystal field caused by spatial and charge non‐equivalency of nearest neighbours of 3d‐ions and also by the lack of an inversion centre. The crystal field operator for ferroelectric and paraelectric phases has been calculated using the point charge model. The expressions connecting crystal field parameters and ion displacements have been derived. The optical absorption of boracites Me3B7O13X where Me = Co, Ni and X = Cl, Br, I has been studied in the spectral range 0.25 to 25 μm from 77 to 700 °K. The absorption spectra are much more complicated than the known spectra of Co2+ and Ni2+ in octahedral cubic crystal field. It was found that the intensity of many transitions in boracites drops when the temperature is raised. The most rapid decrease was observed in the vicinity of the ferroelectric Curie temperature Tc. Such unusual behaviour was assigned to the change of the crystal field odd component connected with unequivalent displacements of halogen ions relatively to the 3d‐paramagnetic ion. The temperature dependence of the tetragonal crystal field parameters Ds and Dt was studied in cobalt boracites. An increase of Ds and decrease of the Dt was observed at Tc in accordance with the theoretical predictions.
The Exciton Binding Energy of III–V Semiconductor Compounds
Authors: Kübler J. K. 
Published: July 2007

AbstractThe experimental data on band structure parameters, external dielectric constants, and exciton binding energies of the III–V semiconductors have been correlated and the deviations of the experimental exciton binding energies from the values predicted by a hydrogenic formula involving the external dielectric constant have been explained. It is shown that the external dielectric constant must be multiplied by an enhancement factor to obtain the dielectric screening constant for the electron‐hole interaction if the energy gaps are small. This enhancement factor is explained theoretically and is obtained explicitely as a function of the gap from the experimental data for the III–V semiconductors.
On the Magnetic Relaxation of Iron‐Rich Ferrites in the Temperature Range 300 to 450 °C
Authors: Maxim Gh. 
Published: July 2007

AbstractUsing the induced anisotropy, the magnetic relaxation effect of MexFe3−xO4+γ ferrites is investigated in the temperature region 300 to 450 °C. It is shown that this effect appears only in the Mn‐Fe and Zn‐Fe ferrites. At small concentrations (x < 0.1) the induced anisotropy is proportional to the concentration of Mn and Zn ions, respectively. It is presumed that this relaxation effect is caused by the directional ordering of some configurations of Mn and Zn ions, respectively, on the tetrahedral sites of the spinel lattice. The ordering is produced by cation diffusion via vacancies.
Evidence for the Coulomb Interaction of Be Valence Electrons by Compton Scattering Cross‐Section Measurements
Authors: Schülke W. , Berg U. , Brümmer O. 
Published: July 2007

AbstractThe effect of Coulomb interaction on the Compton scattering cross‐section (CSCS) of a free electron gas has been calculated theoretically by Ohmura and Matsudaira within the framework of the random phase approximation (RPA). These calculations have shown that plasmon emission during the scattering process diminishes the CSCS against its value within the Hartree‐Fock approximation, which neglects the Coulomb interaction. A method is presented to measure relative values of the CSCS of metal valence electrons by separating the core electron part from the valence electron part of the Compton line profile. The relative values of the CSCS have been brought onto an absolute scale by means of a sum rule for the imaginary part of the dielectric constant given by Noziére and Pines. The measured values of the CSCS of Be valence electrons are in good agreement with the RPA calculations of Ohmura and Matsudaira.
Déformations de cohérence d'un précipité quadratique
Authors: Faivre G. 
Published: July 2007

AbstractOn établit les expressions exactes du champ élastique provenant d'un précipité parfaitement cohérent avec la matrice, en forme de parallélépipède rectangle, en supposant le corps élastiquement homogéne et isotrope. On discute la validité de quelques approximations usuelles. Les déformations calculées sont comparées aux résultats de mesures par rayons X sur des précipités d'un alliage Fe–Ni–Nb. On examine de plus l'influence de la forme du précipité sur l'énergie élastique de cohérence.
Magnetically Influencable Defect Annealing and Other Recovery Effects in Nickel, Observed with Electrical Resistance and Magnetoresistance Data
Authors: Hellenthal W. , Lotter U. 
Published: July 2007

AbstractElectrical resistivity and magnetization processes (using a new magnetoresistance compensation method in alternating fields) were simultaneously observed at 77 °K in connection with recovery between 20 and 300 °C on nickel wires after low tensile deformation. Thn latter method, being very sensitive to recovery processes, reveals numerous details. Anneale ing the samples in different magnetic fields permitted a quantitative evaluation of field‐influencable effects and their separation from other contributions occurring simultaneously‐By careful analysis of some results it was also possible to distinguish transient from simple stage type contributions to the field‐insensitive recovery.
Die Spannungsabhängigkeit der Versetzungsdichte reiner und Mg‐dotierter LiF‐Einkristalle
Authors: Reppich B. 
Published: July 2007

AbstractHochreine und Mg‐dotierte 〈100〉‐orientierte LiF‐Einkristalle wurden verschieden thermisch vorbehandelt und im Druck unter konstanter Last bei Raumtemperatur verformt. Der Zusammenhang zwischen Schubspannung τ und Versetzungsdichte N wurde mittels der Ätzgrübchenmethode untersucht. Die Auswertung berücksichtigt Inhomogenitäten in der Versetzungsanordnung. Ätzversuche unter Spannung zeigen, daß sich Ätzgrübchen‐dichte und ‐anordnung verfestigter Kristalle nach Entlasten nicht sichtbar verändern. τ wird als Funktion von N beschrieben durch τ = αGb \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt N $\end{document}(G: : Schubmodul, b: Betrag des Burgersvektors) über den gesamten Spannungsbreich bis zum Bruch. Die Konstante der Versetzungswechselwirkung ergibt sich zu α = 0,25 unabhängig vom Mg‐Gehalt und der thermischen Vorbehandlung.
The Dislocation Structure of Glide Bands in LiF Crystals Stressed at T = 300 to 1.4°K
Authors: Klyavin O. V. , Nikiforov A. V. , Smirnov B. I. , Chernov Yu. M. 
Published: July 2007

AbstractThe etch pit density and the shear strain in screw and edge glide bands were measured on LiF crystals, stressed at temperatures of 1.4 to 300°K, and the temperature dependence of the average slip distance of screw dislocations and the probabilities of cross slipping are estimated. The slip distance decreases with the temperature down to 78°K, remaining constant, however, at lower temperatures. The cross slip probabilities increase continuously with decreasing temperature.
Phénomènes accompagnant l'ordre directionnel dans un ferrite de fer renfermant un peu de cobalt au‐dessus de la température ambiante
Authors: Marais A. , Merceron Th. , Porte M. 
Published: July 2007

AbstractOn a étudiè l'influence de faibles additions de cobalt sur les propriétés de la magnetite polycristalline. La présence des ions Co2+ contribue à la formation d'une forte anisotropie uniaxiale Ku induite sous champ magnétique aux environs de 100°C. La mesure de Ku à la balance de torsion permet d'obtenir la valeur de l'énergie de couplage élémentaire w de l'ion Co2+ au réseau. Dans le même domaine de température on observe une forte augmentation de la rectangularité par traitement sous champ, ainsi qu'un phénomène nouveau “d'accommodation” de la perméabilité que l'on explique. On étudie aussi l'apparition de cycles d'hystérésis multistables, et les conditions de formation de ces cycles.
A Quasichemical Theory for a Short Range Ordered Alloy with Vacancies.
Authors: Sohoijet M. 
Published: July 2007

AbstractA quasichemical theory for a short range ordered binary alloy containing vacancies is developed using a kinetic approach. The vacancy–atom a posteriori probabilities are obtained. It is shown that if the vacancies are in their equilibrium environment then the atom–atom pair probabilities should also have the values corresponding to the state of thermodynamic equilibrium.
Reformulation of the Theory of Impurity States in Non‐Metallic Crystals
Authors: Glodeanu A. 
Published: July 2007

AbstractThe theory of impurity states is reformulated by using a pseudopotential method. The effective mass and two‐band approximations are obtained. A simple criterion in order to estimate the errors introduced by some hypotheses is found. Finally an equation in a single‐band approximation valid for both deep and shallow levels is derived but with one effective mass and dielectric function in terms of the impurity pseudopotential.
Spin Fluctuations in a Magnetically Ordered Cr2O3–Fe2O3 System
Authors: Srivastava J. K. , Sharma R. P. 
Published: July 2007

AbstractThe study of Mössbauer spectra of the solid solution 0.905 Cr2O3—0.035 Fe2O3 at different temperatures in the range 10 to 293 °K has revealed spin relaxation effects in this antiferromagnetically ordered system in a wide temperature range (100 to 289 °K) below the Néel temperature (289 °K). The variation of the hyperfine field with temperature is found to be almost linear from 10 °K onward. Above 100 °K the hyperfine field calculated from the total splitting is more than that obtained from ground state splitting. The observed results are compared with the existing spin‐flip theory based on a stochastic model.
The Deformable Shell Model Calculation of Infrared Absorption Frequencies of Ionic Crystals
Authors: Roy D. , Basu A. N. , Sengupta S. 
Published: July 2007

AbstractThe deformable shell model which includes many‐body effects and accounts for the breakdown of Cauchy relation is extended to the case of the CsCl structure. The TO mode frequencies for q = 0 are calculated for eight ionic crystals of both NaCl and CsCl structures. For comparison, the shell model values are also calculated. The results are compared with the infrared absorption frequencies. It is found that the deformable shell model gives better agreement than the shell model. The result is particularly striking for crystals showing a large Cauchy relation breakdown.
On the Behavior of Interstitials Produced by Ionizing Radiation in Alkali Halides
Authors: Sonder E. 
Published: July 2007

AbstractThe reactions occurring among radiation‐produced defects after the primary production step are the subject of this paper. For KCl, at liquid nitrogen temperature, the interstitial members of the radiation‐produced Frenkel defects are known to be mobile. A model that has been mentioned repeatedly in the literature is compared with experimental data. In the model, rate equations are used to describe radiation‐produced mobile interstitials which can either recombine with vacancies or can be trapped at other defect sites, causing the corresponding vacancies (F‐centers) to be stabilized. Asymptotic forms and analog computer solutions of simple forms of the equations are obtained. The experimental results include F‐center growth curves which are approximately linear with irradiation dose and which demonstrate that for a wide range of radiation intensities the F‐center production rate is proportional to the dose rate. The predictions of the model are in accord with experimental results only for a rather extreme asymptotic case, for which a different description, which does not require the solution of rate equations, may be equally valid.
Charge Compensation of Impurities and Electrical Properties of MoO3
Authors: Ioffe V. A. , Patrina I. B. , Zelenetskaya E. V. , Mikheeva V. P. 
Published: July 2007

AbstractAn investigation was made of the EPR spectra of MoO3 single crystals grown in air and in argon. In the crystals grown in air and not specially doped no EPR signal was found. For crystals grown in argon a spectrum is observed due to electrons localized on two different sites of the lattice. This spectrum shows a hfs from a nuclear spin I = 1/2. The spin‐Hamiltonian constants are: S = 1/2, I = 5/2 gx = 1.942, gx = 1.953, gx = 1.878, Ax = 32 G, Ay = 69 G. The operator of the hyperfine interaction is of the form

equation image

The splitting of the transitions with ma ≠ mb is equal to 1/3 A. The splitting by the nuclear spin I = 1/2 is nearly isotropic 3 to 4 G. The same spectrum is observed in air‐grown crystals after irradiation with a quartz‐mercury lamp. In copper doped crystals grown in argon the copper is found to be in the state 3d10. After heating the crystal in air the Cu2+ (3d9) spectrum is observed. The constants of the spin Hamiltonian are: S = 1/2, I = 3/2 gx = 2.087, gy = 2.054, gz = 2.416, Ax = 6 G, Ay = 22.5 G, Az = 93.5 G, Qx = 2.9 G, Qy = 3.0 G, Qz = 5.9 G. Suppositions are made about a reason for the unstability of the electrical conductivity of MoO3 according to the data obtained.
On the Higher‐Order Response of a Superconductor
Authors: Weller W. 
Published: July 2007

AbstractThe response of a superconductor to external fields is considered in arbitrary order. The response is calculated for an imaginary time interval and then analytically continued to real times. In this way it is possible to make use of the theorem proved by Kadanoff and Baym on the identity of the correlation functions connected with the physical and the unphysical problem. The result justifies the method of Gorkov and Eliashberg in which the analytic continuation has been performed in the frequency representation.
The Complex Susceptibility of a Uniaxial Ferromagnet
Authors: Potapkov N. A. 
Published: July 2007

AbstractA method is developed for an approximate solution of a chain of equations for two‐time Green's functions. The method is applied to the calculation of the complex susceptibility of a Heisenberg ferromagnet with uniaxial anisotropy. The damping of the uniform precession and the width of the resonance line in the vicinity of the Curie point are found.
Green's Function Formalism for an Anharmonic Metal
Authors: Högberg T. 
Published: July 2007

AbstractThe Green's function formalism for an anharmonic metal has been worked out. From an Hamiltonian which includes the mutual interaction between the electrons, between the ions and between the electrons and ions, the equation of motion of the Green's function for the phonon has been derived, including anharmonic terms to fourth order. The conditions for assuming an effective ion‐ion potential for an anharmonic metal are investigated.
Elektronenspektrum in der Lavesphase MgZn2
Authors: Rennert P. , Lehmann G. , Paasch G. , Taut M. 
Published: July 2007

AbstractDie Energiebandstruktur für MgZn2 wird mit der Pseudopotentialmethode auf den Symmetrielinien der Brillouinzone berechnet. In der Nähe der Fermifläche ergeben sich infolge vieler, eng benachbart liegender Bänder auch bei kleinen Fourierkomponenten des Pseudopotentials wesentliche Abweichungen von der Bandstruktur freier Elektronen.
ESR in Oxygen‐Doped AgBr Crystals
Authors: Höhne M. , Segsa K. H. , Stasiw M. 
Published: July 2007

AbstractAt 14 °K and below oxygen‐doped AgBr crystals irradiated in the temperature range of 100 up to 220 °K show an ESR spectrum, which was not observed in AgBr crystals doped with Ag2Te, Ag2Sc, or Ag2S. The spectrum has axial symmetry with a [100] direction as axis. In order to explain the g‐values and the hyperfine structure a complex consisting of an oxygen atom and six neighbouring silver ions with an electron bound to this complex is proposed.
LCAO–HCO Calculation of Condensed Aromatic Hydrocarbons
Authors: Jäger J. 
Published: July 2007

AbstractThe energy band structure of the π‐electron system of crystalline anthracene was calculated in the LCAO–HCO approximation. The results show a mean band width of the filled bands (in the ground state) of about 0.1 β‐units and an energy gap between the highest filled and lowest unfilled band of about 0.7 β‐units.