bluuebunny/crossref_metadata_2025_split huggingface dataset:
Luminescence and Photoconductivity in Silver Chloride with Laser Excitation
Authors: Laibowitz R. B. , Sack H. S. 
Published: July 2007

AbstractIn zone refined AgCl, luminescence can be excited by ruby laser light through two‐photon processes, while the photoconductivity is a result of ionization of donors. The luminescence spectrum shows some phonon structure not observed with steady uv excitation.
Integral Characteristics of Anomalous Transmission of X‐Rays
Authors: Efimov O. N. , Kovev E. K. 
Published: July 2007

AbstractIntegral characteristics of anomalous transmission of X‐rays are discussed on the basis of experimental and theoretical analysis of the integrated intensity for the case of symmetrical Laue diffraction, (220) germanium reflection and Cu K radiation. Experimental and calculated data are in a good agreement. The physical interpretation of these characteristics and methods for determining them are discussed. The characteristics are valid for “the region of approximation to a thick crystal”, in which only one wave field reaches the exit surface with anomalously low absorption (pure Borrmann effect). The characteristics are connected with the real and imaginary parts of the structure factor, μi ∼ Fih and yi ∼ Frh respectively. The necessity of using both integral characteristics is emphasized by the analysis of a general degree of perfection of the crystals with different types of defects and especially for cases where a “kinematic component” of the scattering is important.
On the Efficiency of Dislocation Climb in Gold
Authors: Seidman D. N. , Balluffi R. W. 
Published: July 2007

AbstractThe climb rate of the three‐dimensional dislocation network in gold is investigated experimentally under the following non‐equilibrium vacancy conditions: 1) supersaturation at elevated temperatures during rapid down‐quenching; 2) supersaturation at lower temperatures following a rapid down‐quench from an elevated temperature; 3) subsaturation during uppulsing and holding at an elevated temperature. It is found that the network climbs with a quite high efficiency under all the above conditions; that is, at a rate which is within a factor of one‐tenth to one of the maximum possible rate calculated on the assumption that vacancy equilibrium is maintained evergwhere along the dislocation cores and that the climb rate is therefore vacancy diffusion limited.
Technique for Measuring the Rate of Growth of Crystals from Solutions in Dependence on the Degree of Supersaturation at Low Supersaturations
Authors: Bennema P. 
Published: July 2007

AbstractA technique is developed for the accurate measurement of the rate of growth R of one type of crystallographic face as a function of the relative supersaturation (σ) for low values of R and σ [1]. The growing crystal is suspended from the arm of a balance and hangs in a closed supersaturated solution. The weight of the crystal and the temperature of the supersaturated solution can thus be measured simultaneously. From numerous results taken at different times the (R, σ) relation can be obtained numerically.
The Effect of Dislocation Dipoles on the Shape of the Nuclear Magnetic Resonance Line
Authors: Greenberg B. A. 
Published: July 2007

AbstractThe effect of dislocation dipoles on the broadening of a NMR line is studied. The shape of the satellite line is determined. The line width is obtained as a function of the dipole concentration, the dipole length and the relative orientation of the dipole and the external constant magnetic field. The shape of the central line is also determined. The shape function of the central line is presented for certain relative orientations of the dipole and the magnetic field.
On the Theory of Free Carrier Electro‐Magneto‐Optical Phenomena
Authors: Kołodziejczak J. , Stramska H. 
Published: July 2007

AbstractThe nonlinear Boltzmann equation is discussed for nonspherical and nonparabolic energy bands assuming strong dc and weak ac electric fields. The current density is calculated in the limit of a quadratic deviation from Ohm's law. Freecarrier magneto‐optical phenomena in the presence of a strong dc electric field are discussed.
Anordnungen paralleler Versetzungen in anisotropen Medien
Authors: Seeger A. , Wobser G. 
Published: July 2007

AbstractFür zwei parallel laufende, geradlinige Versetzungen im kubisch‐flächenzentrierten bzw. hexagonal dichtestgepackten Gitter, die sich auf zwei parallelen dichtestgepackten Ebenen bewegen, werden die stabilen Konfigurationen ermittelt. Dabei werden alle möglichen Kombinationen von Burgersvektoren in 〈110〉‐ bzw. 〈2110〉‐Richtungen, also nicht nur sogenannte Versetzungsdipole, in Betracht gezogen. Die Rechnungen werden unter Berücksichtigung der elastischen Anisotropie (im Fall des kubischen Gitters für Versetzungen in 〈110〉‐oder 〈211〉‐Richtungen) durchgeführt. Für eine Reihe von Metallen sowie Ge und Si werden die stabilen Gleichgewichtskonfigurationen sowie die zum Aufbrechen derselben benötigten Kräfte angegeben. Im Anhang werden die mit der anisotropen Elastizitätstheorie berechneten Spannungskomponenten für Versetzungen in 〈110〉‐ und 〈211〉‐Richtungen in kubischen Kristallen sowie für Versetzungen in der hexagonalen Basisebene zusammengefaßt. Die in diesen Gleichungen auftretenden Materialkonstanten werden in Tabellenform angegeben.
Berechnung des Debye‐Waller‐Faktors von Nickel
Authors: Gleiss R. 
Published: July 2007

AbstractEs ist das Ziel dieser Arbeit eine einfache Methode anzugeben um den Debye‐Waller‐Faktor f für Nickel auszurechnen. Dazu wird von der harmonischen Gittertheorie ausgegangen. Sie liefert eine einfache Formel für f, die sich für hohe und tiefe Temperaturen in eine Reihe entwickeln läßt. In dieser treten die Momente des Schwingungsspektrums auf und Konstanten, die mit der spezifischen Wärme C zusammenhängen. Die Momente werden aus gemessenen Frequenzspektren und aus Rechnungen über ein 2‐Nachbar‐Gitter‐Modell ermittelt. Man kann sie aber auch aus der experimentell bestimmten Temperaturabhängigkeit von C erhalten. Die so berechneten f(T)‐Werte stimmen im Rahmen der Meßgenauigkeit gut mit dem Experiment überein. Die Methode läßt sich auch auf andere kubische Kristalle anwenden.
The LCAO Method for an Arbitrary Mixture of Atoms
Authors: Gubanov A. I. 
Published: July 2007

AbstractA new method for quantum‐mechanical calculations for electrons in a disordered mixture of atoms is proposed. This method is based on the linear combinations of atomic orbitals and uses the binary distribution function of atoms. To restrict the number of equations a finite number of atoms is chosen and an averaging over the configurations and types of atoms is performed. This method can be used to calculate the energy spectrum and wavefunctions of electrons in liquid and amorphous semiconductors, as well as in liquid and solid disordered alloys.
On the Conduction Mechanism in Uranium Dioxide
Authors: Devreese J. , De Coninck R. , Pollak H. 
Published: July 2007

AbstractExperimental data on the thermoelectric power and electrical conductivity of nearly stoichiometric UO2+x single crystals are presented and analysed in order to estimate the activation energy of the drift mobility. These results are compared with the predictions of small polaron theory. Although some further analysis is required, there is evidence that conduction in UO2+x occurs via a hopping mechanism.
Interpretation of the temperature dependence of Ag+ dipole strengths in alkali halides
Authors: Dreybrodt W. , Fussgaenger K. 
Published: July 2007

AbstractThe absorption spectrum of Ag+ doped RbCl is measured at various low temperatures in the spectral range from 6.4 to 5.0 eV. The temperature dependence of the Ag+ dipole strength in RbCl is different from that found in NaCl, KCl, and KBr. The different temperature behaviours are interpreted as being due to the different lattice potentials seen by the Ag+ in the various host crystals. The static potentials for Ag+ in the crystals are calculated by a semiphenomenological method. For NaCl, KCl, and KBr a potential minimum is found at the symmetry centre. For RbCl, however, a potential barrier exists at the symmetry centre and potential minima occur at 0.25 Å away from the centre in the [111] direction.
Properties of the B‐centre in additively coloured Ag+ doped KCl crystals
Authors: Degrieck W. , Jacobs G. 
Published: July 2007

AbstractAdditively coloured silver‐doped KCl single crystals grown from highly purified material are examined. A method is developed for obtaining crystals containing only B‐centres. This investigation reveals the presence of two components in the so‐called B band. Several experiments contradict the theory that B‐centres comprise a Ag+ ion associated with an F‐centre. Irradiation at higher temperatures gives rise to a series of new absorption bands. The rate of formation of these bands is greatly affected by the presence of vacancies. By an appropriate thermal treatment the new bands can be bleached and the original B absorption restored.
Diffusion of tritium from lithium fluoride
Authors: Matzke Hj. 
Published: July 2007

AbstractThe release of tritium from neutron irradiated LiF single crystals (5.4 × 1016 nvt, at approximately 300 °C) follows the relation D = 6 exp (−38800/RT) cm2s−1 between 500 °C and the melting point. Volume diffusion kinetics are obtained from isothermal experiments. The tritium diffusion is found to be essentially independent of the neutron dose (3 × 1016 to 3 × 1017 nvt) and nominal temperature during irradiation (−80 to 200 °C). Data obtained following ion bombardment confirm these results.
The fine structure of spots in electron diffraction resulting from the presence of planar interfaces and dislocations
Authors: Gevers R. , van Landuyt J. , Amelinckx S. 
Published: July 2007

AbstractA theory is developed which accounts for the fine structure of electron diffraction spots due to the presence of imperfections of different types in thin foils. The method consists essentially of considering the diffraction pattern to result from the image (i.e. from the amplitudes of transmitted and scattered beams at the exit surface of the foil) by Fourier transformation. The image is described by the expressions given by the two‐beam column approximation assuming the symmetrical Laue case to be realized. The use of the method for the present problem is justified. The geometry of the fine structure and the intensities of the different components of the transmitted and scattered beams are then calculated for a general planar interface taking anomalous absorption into account in the usual phenomenological way. A detailed discussion is given for the special case of a stacking fault. In particular the relation between the properties of the fringe patterns and the fine structure of the transmitted and scattered beams is emphasized. In part II observations will be reported on crystals containing stacking faults which lend support to the theory developed here. In part III crystals containing domain boundaries will be discussed and part IV will be devoted to the study of the diffraction effects of other types of geometrical imperfections.
Beitrag zur Widerstandsmessung von nn+‐ und pp+‐Epitaxialschichten nach dem Durchbruchsverfahren
Authors: Frank H. 
Published: July 2007

AbstractNach kurzer Übersicht über die wichtigsten zerstörungsfreien Meßmethoden zur Bestimmung des spezifischen Widerstandes von Epitaxialschichten wird eine verbesserte Elektrodenanordnung des Durchbruchsverfahrens für einen einfachen Halbleiter‐Metall‐Spitzenkontakt angegeben. Die empirisch ermittelte Eichkurve wird für den Fall der dicken Sperrschicht auf Grund eines einfachen Modells nach der Schottky'schen Sperrschichttheorie begründet. Das Ergebnis zeigt, daß bei geeigneter Wahl zweier Parameter eine befriedigende Übereinstimmung zwischen empirischer und theoretischer Eichkurve für Widerstände größer als 0,1 Ωcm bei Si, Ge und GaAs erzielt werden kann. Bei Widerständen unter 0,1 Ωcm wird für den Fall der dünnen Sperrschicht an n‐GaAs empirisch festgestellt, daß die in der Sperrschicht bei Spannungsdurchbruch auftretende Leistung bezogen auf die mittlere freie Weglänge konstant ist. Aus dieser Beziehung folgt, daß die Durchbruchsspannung der Trägerbeweglichkeit und der dritten Wurzel des spezifischen Widerstandes proportional ist. Die Übereinstimmung mit den Meßwerten an GaAs, Si und Ge im Bereich niedrigen spezifischen Widerstandes ist sehr gut.
Photoluminescence of GaAs0.7P0.3
Authors: Tuck B. 
Published: July 2007

AbstractThe fluorescence of n‐ and p‐type GaAs0.7P0.3 under conditions of optical excitation is described. Measurements were made at 300 and 77 °K. In the as‐grown state the crystals were n‐type. They were made p‐type by diffusing in zinc and comparison was made between the fluorescence of the n‐ and p‐type specimens. At 77 °K, low‐energy spectral lines were found in the p‐type specimens in addition to that due to recombination via the zinc centre. One of these has an intensity which depends on the position of the Fermi level. Another of them appears to be associated with the presence of arsenic vacancies.
Photoconductivity and drift mobilities in single crystal realgar (As4S4)
Authors: Street G. B. , Gill W. D. 
Published: July 2007

AbstractThe photoconductivity and carrier mobilities of synthetic crystals of realgar (As4S4) have been investigated. A sharp increase in the photoresponse at short wavelengths is attributed to an energy gap of (2.40 ± 0.05) eV. An additional weak peak in the photoresponse at 600 nm is due to free hole formation at defect or impurity sites. Electron and hole mobilities have been measured over the temperature range from 250 to 470 °K. At 25 °C the hole mobility was 12 cm2V−1s−1 and the electron mobility 2 × 10−2 cm2V−1s−1. The hole transport can be described by band conduction controlled by lattice scattering. The electron changes is consistent with an intermolecular hopping process which at low temperatures transport to a trap‐controlled mechanism.
Quantum theory of the electrical conductivity of semiconductors with a non‐standard energy band
Authors: Askerov B. M. , Gashimzade F. M. 
Published: July 2007

AbstractThe theory developed by Adams and Holstein is generalized to the case of an isotropic but non‐parabolic energy band, such as the conduction band in InSb. The problem of the electron spectrum in crossed electric and magnetic fields is solved taking into account all the interactions of the conduction band with the valence bands. It is shown that in this case, as for a parabolic band, an electric field appears in the spectrum within the linear approximation. The solution of the equation of motion for the density matrix shows that the non‐parabolicity enters into the dissipative current only through the energy conservation law or the scattering process. The general formula for the electrical conductivity tensor is applied to degenerate semiconductors; Shubnikov‐de‐Haas oscillation conditions are obtained when spin splitting of the Landau levels is considered and the positions of the oscillation maxima are calculated. Inelastic electron scattering by optical phonons is also considered. The conditions for magnetophonon resonance in semiconductors with non‐parabolic energy bands are derived. It is demonstrated that all the maxima of Gurevich‐Firsov oscillations except the first have the natural width.
Die Ausläuferabsorption chalkogendotierter AgBr‐Kristalle bei variabler Fremdkationenkonzentration
Authors: Schwarz D. 
Published: July 2007

AbstractDurch den Einbau zweiwertiger Fremdkationen in AgBr‐Kristalle, die bereits zweiwertige Fremdanionen enthalten, wird die der Eigenabsorption langwellig vorgelagerte Ausläuferabsorption beeinflußt. Bei −190 °C besitzt diese Ausläuferabsorption eine Bandenstruktur. Falls die Kationenkonzentration hinreichend klein ist, wird eine Erhöhung der Ausläuferbande festgestellt. Die Deutung dieser Messungen gelingt mit der schon früher verwendeten Modellvorstellung über die Struktur der absorbierenden Zentren; dem zweifach negativen Chalkogenion auf Anionengitterplatz sowie der Annahme von Frenkel‐ und Schottkyfehlordnung.
On the mechanism of lattice electromigration in metals
Authors: Klotsman S. M. , Timofeev A. N. , Trakhtenberg I. Sh. 
Published: July 2007

AbstractValues of the “residual resistivity” B for ions of silver diffused into copper and gold over a temperature range above 0,8 Tm are calculated on the basis of data taken from a previous paper of Archipova, Klotsman, Timofeev, and Trakhtenberg [1]. These values of B are compared with values of the residual resistivity for substitution and interstitial impurity ions in group I noble metals. This shows that scattering by the diffused ions occupying interstitial positions gives the main contribution to the driving force of the activated complex. The observed temperature dependence of B and the order of magnitude of the temperature coefficients (B−1 ∂B/∂T ≈ 10−4 deg−1) can be explained by the interaction of impurity ions in interstitial positions with the surrounding lattice. As a first approximation this interaction can be considered as a mutual deformation of the impurity ion and the lattice. Using this approximation it is possible to estimate the magnitude of B for impurities from various parts of the periodic table in a given lattice.
Magnon Contribution to the Low‐Temperature Specific Heat of UO2
Authors: De Batist R. , Gevers R. , Verschueren M. 
Published: July 2007

AbstractThe contribution of acoustical phonons to the low‐temperature specific heat of UO2, as calculated from the single crystal elastic constants, is much too small to account for the observed heat capacity. It is shown here that this data can however be explained in terms of antiferromagnetic magnons. An expression for the heat capacity due to spin waves is derived, firstly for a simple antiferromagnet having a spherically symmetric dispersion relation, and secondly for UO2, where the dispersion relation is cylindrically symmetrie. For UO2 it is found that the next nearest neighbour interactions must be included in order to obtain a meaningful dispersion relation.
A Zener‐Damping Peak in Fe‐4 Wt% Si
Authors: Boesono Ir. , Ernst G. J. , Lemmens M. C. , van Langen M. J. , De Vries G. 
Published: July 2007

AbstractThe internal friction of a 4% SiFe alloy is measured in the region 400 to 700°C using single crystal specimens. A Zener peak is found in this temperature range. The results for the relaxation time τ = τ0 exp [Q/RT] are: τ0 = 8 × 10−20±0.6 s; Q = (69±2.5) × 103cal/mol for the [100] direction; τ0 = 1.7 × 10−19±0.3 s, Q = (69±1.5) × 103 cal/mol for the [111] direction.
Adiabatic, Isothermal, and Intermediate Pressure Derivatives of the Elastic Constants for Cubic Symmetry. I. Basic Formulae
Authors: Barsch G. R. 
Published: July 2007

AbstractThe thermodynamic relations between the adiabatic pressure derivatives of the adiabatic elastic constants, the isothermal pressure derivatives of the isothermal elastic constants, and the isothermal pressure derivatives of the adiabatic elastic constants that can be measured ultrasonically are compiled and correctly proved for cubic symmetry. Also, the corresponding relations between the linear combinations of the third‐order elastic constants that can be determined from these pressure coefficients are derived.
Unstable Dislocations in Anisotropic Crystals
Authors: Head A. K. 
Published: July 2007

AbstractIn an elastically anisotropic crystal, the energy of a dislocation depends on the crystallographic direction of the dislocation line. A straight dislocation which is in a high energy direction may be unstable with its energy decreasing if it changes to a zig‐zag shape. The relation between two different criteria of instability is clarified. The theory is used to examine seven possible slip systems in three metals. Instabilities are predicted for six systems in β‐brass, two in iron, and none in niobium. Tables are given of the predicted instabilities for the 〈110〉 {111} f.c.c. system and the 〈111〉 {110} b.c.c. system for a range of elastic constants. A preliminary report is given of the observation of this phenomenon in β‐brass.
Thermal Oxidation of Silicon: Growth Mechanism and Interface Properties
Authors: Revesz A. G. 
Published: July 2007

AbstractThe thermal oxidation of silicon is controlled by impurities, most likely Na and/or OH (as originating from H2O or H2). The latter is the main participant under very clean conditions. In situ cleaning, oxidation, and annealing of silicon results in a SiSiO2 interface that is essentially free of surface states and shows no interface instability effects. Some of the impurities responsible for the oxide growth also contribute to ion migration through the oxide under bias at elevated temperature. The extent of this ion migration is generally very small for specimens processed by this in situ technique.
Temperature and Strain Rate Dependence of the Flow Stress in Molybdenum
Authors: Guiu F. 
Published: July 2007

AbstractThe effect of orientation on the temperature and strain rate ependence of the flow stress of molybdenum single crystals is investigated over the temperature range from 195 to 413°K. The values of the activation parameters ΔH, w, and v are calculated assuming that a single mechanism is rate controlling. It is found that the activation volume at constant stress is a function of the temperature. This together with other results suggest that the deformation is controlled by more than one thermally activated mechanism. An explanation is proposed based on both the overcoming of the Peierls barrier, and the non‐conservative movement of jogs in screw dislocations. The results also indicated that in the range of temperatures from 300 to 350°K there is a change in the rate controlling deformation process.
Contributions to the Mechanism of the Procopiu and Inverse Wiedemann Effects
Authors: Rothenstein B. F. , Policec A. , Anghel C. , Lupulescu M. 
Published: July 2007

AbstractA study is made of the form of the electromotive force induced by the Procopiu effect or by the inverse Wiedemann effect in a search coil surrounding the ferromagnetic specimen. This provides information regarding the relative positions of the specimen axis and easy axis, and the torsion of the specimen.
Free Carrier Electro‐Magneto‐Optical Phenomena in Semiconductors
Authors: Kołodziejczak J. , Kierzek‐Pecold E. 
Published: July 2007

AbstractCalculations are made of free carrier magneto‐optical phenomena in the presence of an external d.c. electric field assuming a quadratic deviation from Ohm's law. The calculations are based on the assumption of non‐parabolic energy bands with spherical symmetry. Expressions are obtained for the Faraday effect, and the Voigt effect in a d.c. electric field as well as for the electro‐optical Kerr effect in a magnetic field.
Verformungs‐ und Temperaturabhängigkeit der Magnetisierungsprozesse in Nickeleinkristallen II. Blochwandverschiebungen und Drehungen der spontanen Magnetisierung in 〈001〉‐Nickeleinkristallen
Authors: Köster E. 
Published: July 2007

AbstractDie Magnetisierung und die magnetostriktive Längenänderung stabförmiger Nickeleinkristalle mit <001>‐Achsenrichtung wurden in Abhängigkeit von der plastischen Verformung und der Temperatur gemessen. In kleinen Feldern erfolgt die Magnetisierung gleichzeitig durch Wandverschiebungen und Drehungen; Magnetisierung und Längenänderung werden durch das Rayleigh‐Gesetz beschrieben. Der Anteil der Wandverschiebungen an der Anfangssuszeptibilität ist proportional zu (τ – τ0)−1, der der Drehungen ist proportional zu (τ – τ0)−2 und macht etwa 15 bis 30% der Gesamtsuszeptibilität aus. Hierbei ist (τ – τ0) die Verfestigung der Kristalle. Aus den Messungen kann die Spannungsanisotropie bestimmt werden, die eine Aussage über die Versetzungsanordnung zuläßt. In der Arbeit werden weiter die Ergebnisse aus Untersuchungen irreversibler Magnetisierungsprozesse entlang der ganzen Magnetisierungskurve mitgeteilt.