bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Self‐Energy of Dislocation Configurations Made up of Straight Segments
Authors: de Wit R. 
Published: July 2007

AbstractThree general expressions are presented: the first is the interaction energy between two non‐parallel straight dislocation segments, the second is the interaction energy between two parallel straight segments, and the third is the self‐energy of a straight segment. These can be used to determine the total energy of any dislocation configuration made up of piecewise straight segments. They differ from previous expressions in the literature primarily in that they are given completely in vector notation and in that the self‐energy includes a core traction term. The expressions are limited to the case of a linear, isotropic, infinite continuum. As an example, the formulas are applied to the case of a stacking‐fault tetrahedron.
Te and Se Centres in AgBr. II. Electronic Structure
Authors: Höhne M. , Stasiw M. 
Published: July 2007

AbstractThe electronic structure of the paramagnetic centre described in Part I is discussed. This centre turns out to be a Se3− – or Te3− – pseudomolecule with 110‐direction. The g‐values and the hyperfine constants of Se3− – but not of Te3− – can be described by assuming the spin‐orbit‐coupling to be small compared with crystal field splitting and neglecting overlap of the atomic wave functions. The ground state wave functions of Te3− are calculated without restriction to small spin‐orbit‐coupling. This method turns out to be not sufficient in the case in question, because overlap plays an important role.
F‐Centres in Alkaline Earth Fluorides
Authors: Feltham P. 
Published: July 2007

AbstractThe ls‐2p transition energy of electrons trapped at fluorine ion vacancies in BaF2 is calculated by means of a continuum approximation, allowing for polarisation. The lattice potential is determined from that previously [8] derived in the evaluation of the F‐centre absorption frequency in CaF2, taking into account lattice isomorphism and differences in the core structures of the respective cations. The calculated value of the energy agrees well with that obtained in additively coloured BaF2 crystals [1] by ESR.
Radio‐Frequency Size Effects in Cadmium in Magnetic Fields Inclined to the Sample Surface
Authors: Naberezhnykh V. P. , Maryakhin A. A. 
Published: July 2007

AbstractThe r.f. size effect is investigated in cadmium, for different field slopes relative to the surface, using a frequency of 5 MHz and magnetic fields up to 104 Oe. When the angle between H and the basic plane of the “lens‐shaped” Fermi surface of the third band is less than 32°, some sections are found with the extremal value of \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{\partial S}}{{\partial K_H }}} \right) $\end{document}, giving the size effect along spiral paths. For H ⊥ [0001] these sections involve KH = 0.41 Å−1 with \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{\partial S}}{{\partial K_H }}} \right)_{ext} $\end{document} = (1.112 ± 0.03) Å−. By changing the field slope angles from zero to 90°, and rotating H in the basic plane, it is possible to observe the change in character of the impedance oscillations on the spiral paths. For slope angles between 7° and 17° the size effect lines at the spherical support point of the „lens”︁ are also observed. This gives the radius of curvature as (1.32 ± 0.1) Å−1.
External Photoeffect from Sensitizing Dyes Adsorbed on Semiconductors
Authors: Akimov I. A. , Bentsa V. M. , Vilesov F. I. , Terenin A. N. 
Published: July 2007

AbstractA study is made of the spectral distributions of the internal and external photoeffect for ZnO, AgBr, and TlJ before and after dyeing by sensitizers. The results obtained indicate that the excited dye level is situated below the bottom of the conduction band of the n‐type semiconductors (ZnO, AgBr), and that the top of the valence band of the p‐type semiconductor (TlJ) is situated below the ground level of the dye sensitizer. Hence, the spectral sensitization does not occur by charge transfer, but by energy transfer.
Étude de la variation de longueur du plutonium α par autoirradiation à 4 °K
Authors: Lallement R. , Wigley D. A. 
Published: July 2007

AbstractNous avons mesuré l'allongement du plutonium α maintenu dans l'hélium liquide. La longueur du plutonium augmente en suivant une loi de la forme ΔL/L = A [1 − exp(−α t)] avec α = 2,2 × 10−4/h et A = 2 × 10−2. La comparaison avec les résultats relatifs à la résistivité montre que la longueur se sature bien moins vite que la résistivité. Cette différence permet de comprendre qualitativement l'existence d'un maximum dans la variation de résistivité avec le temps. La comparaison des deux résultats montre aussi que la saturation de la résistivité n'est pas liée à la saturation de la production des défauts. Des recuits isochrones ont montré l'existence de deux stades de recuits pour les défauts d'autoirradiation, l'un vers 80 °K, l'autre vers 160 °K.
The Influence of Annealing on the Structure of Polycrystalline Permalloy Thin Films
Authors: Puchalska I. B. , Sukiennicki A. , Petykiewicz Z. , Tymosz T. 
Published: July 2007

AbstractA study is made of the effect of annealing on the structure of permalloy polycrystalline thin films. Thin films of 85% Ni‐15% Fe are investigated using an electron microscope at high temperatures. The results show that annealing causes the growth of irregularities in the thin film surface. In extreme cases this may invalidate the concept of a uniform thin film thickness. The growth of crystallites is not isotropic but occurs most vigorously in the surface of the thin film.
The Influence of the Magnetic Field on the Domain Structure of Ferrimagnetic Oxides with High Anisotropy Field
Authors: Rosenberg M. , Tanasoiu C. , Florescu V. 
Published: July 2007

AbstractThe magnetization process of SrO × (6 − x) Fe2O3 × x Al2O3 single crystals (with 0 ≦ × ≦ 2) is investigated by recording the modifications of the domain structure under the influence of an external magnetic field. It is found that this process occurs in two stages: in the first stage, at lower fields, the magnetization occurs mainly by Bloch wall displacements; in the second stage (at higher fields) regions of the inverse magnetized domains, or entire domains of this type suddenly collapse. For samples with x = 0 and 1 honeycomb domain structures can be obtained by applying a magnetic field along the hard direction.
The Effect of Systematic Reflections on the (110) Extinction Distance in Molybdenum
Authors: Sheinin S. S. 
Published: July 2007

AbstractThe dependence of the (110) extinction distance in molybdenum on Δθ, the deviation from the exact Bragg condition, has been investigated. The results indicate that near the exact Bragg condition (0° < Δθ < 0.5°) the two‐beam theory is in good agreement with experiment. For larger values of Δθ the effects of systematic reflections become important. The agreement between the multi‐beam theory and experiment is excellent for values of Δθ greater than 1.25°. However, for intermediate values of Δθ where the depth periodicities are complex, neither the two‐ or multi‐beam theories give an adequate description of the experimental results obtained.
Untersuchung der anisotropen Abbremsung von niederenergetischen Magnesiumatomen in einem NaCl‐Einkristall bei verschiedenen Temperaturen
Authors: Dutta B. C. , Holtmeyer G. , Kalus J. 
Published: July 2007

AbstractEs wurde die Kernresonanzfluoreszenz‐(KRF‐)Ausbeute am 1,37 MeV‐Niveau von Mg24, das durch Neutronenbestrahlung von Na23 in einem NaCl‐Einkristall erzeugt wurde, in Abhängigkeit von der Kristallorientierung und Temperatur gemessen. Abhängig von der Temperatur war die KRF‐Ausbeute bei Emission der γ‐Quanten in <110>‐Richtung bis zu 18% größer als bei Emission in < 100 >‐Richtung. Die Ursache der Temperaturabhängigkeit ist eindeutig auf Diffusionsprozesse zurückzuführen. Aus Rechnungen, die mit einem Hartkugelmodell durchgeführt wurden, ergibt sich, daß bei Zimmertemperatur die Gleichgewichtslage des Mg‐Atoms ein raumzentrierter Zwischengitterplatz ist.
Calculations of Dispersion Curves and Specific Heat for LiF and NaCl Using the Breathing Shell Model
Authors: Nüsslein V. , Schröder U. 
Published: July 2007

AbstractThe model for the lattice dynamics of alkali halides as given in a previous paper is generalized to include the case in which both ions are polarizable. Dispersion curves and density of states are calculated for LiF and NaCl at 0 °K. The Debye characteristic temperatures ΘD(T) for 0 °K and 300 °K are computed for these crystals, and good agreement with experimental values is obtained.
Electric Conductivity and Dielectric Absorption Phenomena in Lead Zirconate Ceramics
Authors: Handerek J. 
Published: July 2007

AbstractChanges in the electrical conductivity of PbZrO3 in the temperature range 200 to 270 °C are investigated using gold, silver and platinum electrodes. Within this temperature range it is found that a spontaneous current exists in the sample showing changes with temperature analogous to the changes governing the electric conductivity. Study of absorption currents when the polarization field is switched off, reveals current hysteresis loops reminescent of electrical hysteresis loops in ferroelectric materials. Hence, the results obtained indicate the presence of a ferroelectric phase in PbZrO3 as well as an electronic mechanism of conductivity.
Determination of Spin Directions and Electric Field Gradient Axes in Vivianite by Polarized Recoil‐Free γ‐Rays
Authors: Gonser U. , Grant R. W. 
Published: July 2007

AbstractNon‐polarized and linearly polarized recoil‐free γ‐rays (Mössbauer effect) have been used to determine spin directions and the orientation of the electric field gradient (EFG) principal axes for the two iron sites in vivianite. The values obtained for the internal fields, quadrupole splittings, isomer shifts, and the relative orientations of the internal fields and EFG principal axes with respect to the crystal axes are tabulated.
Localized States in Disordered Lattices
Authors: Mott N. F. , Allgaier R. S. 
Published: July 2007

AbstractThis paper investigates the conditions under which localized states occur in three dimensional disordered systems, and considers the relevance of a large body of experimental data on liquids which exhibit non‐metallic behaviour in their conductivities. It is suggested that in many liquids a “pseudogap” a deep minimum in the density of states will occur. It is argued that localized states will appear in this pseudogap when the density of states drops to roughly half its free electron value and that the mean free path is then approximately equal to the wavelength of the electron. It then follows that “hopping” conductivity increasing with increasing temperature will appear when the magnitude of the conductivity falls below a certain value, computed to be in the neighbourhood of 300 Ω−1cm−1. An examination of the known data on about 90 liquids near their melting point suggests that this is in fact the case.
Herring‐Nabarro Creep Studies on the Self‐Diffusion of Iron in the Presence of Solutes
Authors: Hondros E. D. 
Published: July 2007

AbstractCreep studies have been conducted on pure iron and iron alloys at high temperatures and in the stress range where the Herring‐Nabarro diffusion creep mechanism pertains. Results are presented which show that the diffusion coefficient of pure iron in the δ‐phase agrees within experimental error with the radio‐tracer value and that nitrogen and phosphorus in dilute solid solution enhance the self‐diffusivity of pure iron. The self‐diffusion of iron in the presence of 3.5% Si is expressed by

.
Etude théorique et expérimentale du contraste des images de dislocations
Authors: Balibar F. , Authier A. 
Published: July 2007

AbstractOn compare la distribution d'intensité observée pour une image de dislocation par topographie aux rayons X à celle calculée à l'aide de la théorie de Takagi, pour la même dislocation. Les résultats sont en bon accord. En particulier, on retrouve bien par le calcul les différentes régions de l'image de dislocation avec leurs contrastes respectifs (“image directe”, “image dynamique”, “images intermédiaires”).
Ion‐Bombardment Enhanced Solubility in Solids
Authors: Jech Č. 
Published: July 2007

AbstractTwo labelling techniques are developed which are based on injection of small concentrations of radioactive atoms with a known concentration profile. These techniques are used for studying enhancement of solubility in mica, Al2O3, and NiO induced in these substances by bombardment with Kr ions with energies in the keV region. Mica is found to be the most sensitive, an enhanced solubility of the surface layer being detected for doses as low as 5 × 1012 ions/cm2. The depth of the soluble layer is found to be comparable with the range of the ions. The effects of ion bombardment on solubility seem to arise from lattice damage resulting from the bombardment rather than from the presence of the injected gas.
Energy Distribution of Photoelectrons Created by Al Kα X‐Rays in Alkali Halide Targets
Authors: Karras M. , Suoninen E. 
Published: July 2007

AbstractThe spectra of photoelectrons created by AlKα X‐rays are investigated in CsJ, CsF, LiJ, and LiF photocathodes. The energy distributions of the photoelectrons are determined by measuring the photoelectric current between two concentric spherical electrodes with a variable retarding potential between them. For a LiF target, the electron spectrum is analysed quantitatively using an analytical model for the energy distribution of the K photo and K → LL Auger electrons from fluorine atoms. A strong deviation from Whiddington's law is found for the penetration model of the electrons.
Pressure Derivatives of the Elastic Constants of NaBr and KF
Authors: Koliwad K. M. , Ghate P. B. , Ruoff A. L. 
Published: July 2007

AbstractThe isothermal pressure derivatives of the adiabatic second order elastic constants at 25 °C of NaBr and KF have been measured by the ultrasonic interferometric technique. The results are:
magnified imageHere c′αβ = ―ϱ where ―ϱ is the density and Vαβ is the velocity at the given pressure and temperature. These pressure derivatives are analyzed in the framework of the Born model of ionic solids. The pressure derivatives of the second order elastic constants can be expressed in terms of the second and third order elastic constants. The theoretical values of the second and third order elastic constants used in this article were obtained by considering the coulombic interactions of point ions, short range repulsive interactions up to second nearest neighbors, and van der Waals terms. Even though there is qualitative agreement between theory and experiment quantitative agreement is less satisfactory than desired.
The Effect of the E(k)‐Relation on Tunneling through Asymmetric Barriers
Authors: Gundlach K. H. , Heldmann G. 
Published: July 2007

AbstractThe tunneling current through an asymmetric trapezoidal potential barrier depends on the polarity of the applied voltage. The magnitude of this polarity effect depends on (amongst other factors) the relation between the energy E and the attenuation coefficient χ — the imaginary component of the wave number k. In the theory of electron tunneling the free‐electron parabolic E(k)‐relation is usually used. It is not however possible to explain the considerable polarity effect observed in Al‐Al2O3‐Al films by using the parabolic E(k)‐relation. By using an E(k)‐relation which describes the complex band structure of the insulator at least qualitatively good agreement is obtained between theory and experiment.
Influence of Defects and of the Interaction between them on Phonon Scattering in Heavily Doped Ge and Si Crystals
Authors: Arasli D. G. , Aliev M. I. 
Published: July 2007

AbstractMeasurements are made of the thermal conductivity x of highly doped Ge and Si monocrystals. At 300 °K x starts to decrease with increasing impurity concentration for concentrations greater than 1017 cm−3 in Ge and 1018 cm−3 in Si. Heat transfer in these crystals occurs primarily via the phonons and the observed decrease of x as a function of concentration is connected with phonon scattering. An estimate is made of the thermal resistance due to impurities, complexes of atoms of the doping impurity, vacancies, and carriers. Hence, the types of defect which are the main centres of phonon scattering can be determined. It is shown that in p‐Ge the additional thermal resistance ΔW is due to phonon‐scattering by the impurities and carriers, but in n‐Ge phonons are scattered by complexes and vacancies. In n‐Si ΔW is caused primarily by phonon scattering by impurities.
Arrays of Dislocation Dipoles in Cadmium
Authors: Blasdale K. C. A. 
Published: July 2007

AbstractSymmetrical edge dislocation quadrupoles and linear edge multipoles have been observed by an etch‐pit technique in cadmium single crystals. The observed dimensions of the quadrupoles are in good agreement with the predictions of anisotropic elasticity, but those of the multipoles can be reconciled with theory only if it is assumed that dislocation movement is resisted by a force of frictional type. The required frictional resistance is of the right order of magnitude to account for the observed critical shear stress. For multipoles containing small numbers of dislocations in cadmium and in an isotropic medium, equilibrium configurations and configurations to be expected under small resistive forces have been calculated. Possible mechanisms for producing the multipoles are discussed.
Effect of Donor Impurity Concentration on the Piezoresistance of n‐Type GaSb
Authors: Averous M. , Bougnot G. 
Published: July 2007

AbstractMeasurements are made of the change of resistance under uniaxial stress of several single crystal samples of n‐type GaSb with different carrier concentrations (5.7 × 1017 to 1.6 × 1018 donors/cm3) from 77 to 300 °K. The piezoresistance coefficients as functions of temperature are found to pass through an extremum. This extremum shifts to higher temperatures as Nd increases. It is concluded that the dominant effect of uniaxial stress, in the presence of mixed conduction involving the two conduction band minima (lowest minimum (000) and the next minimum (111)), is to cause a change in the energy separation of these minima.
Time Lag in Heterogeneous Nucleation due to Nonstationary Effects
Authors: Toschev S. , Gutzow I. 
Published: July 2007

AbstractThe basic expression for the time lag in nonstationary nucleation in a homogeneous medium is discussed in some detail. Since heterogeneous nucleation is dominant in phase transitions, formulas may be developed to account for the influence of the substrate on the time necessary to establish a stationary nucleation rate. The following models are considered: isotropic nuclei on a solid substrate, crystalline nuclei on a solid substrate and isotropic nuclei growing by surface diffusion of components previously adsorbed onto the substrate. The analysis shows that the time lag is usually smaller than that of the homogeneous case under the same conditions.
Zur Berechnung der Fehlordnung in Silberhalogeniden
Authors: Müller P. 
Published: July 2007

AbstractEs wird gezeigt, daß bei der Berechnung der Parameter für die thermische Frenkelfehlordnung in AgBr und AgCl sowohl die Wechselwirkung der Fehlstellen untereinander als auch die 200 grd unterhalb des Schmelzpunktes beginnende verstärkte Volumenausdehnung berücksichtigt werden muß. Es werden quantitative Angaben über den absoluten Fehlordnungsgrad und die Beweglichkeiten der Fehlstellen gemacht.
Theory of Spin‐Lattice Relaxation of Conduction Electrons of Ionic Semiconductors at Extremely High Magnetic Fields
Authors: Kalashnikov V. P. 
Published: July 2007

AbstractA longitudinal spin‐lattice relaxation time T1 is considered for conduction electrons due to optical phonons scattering in a high magnetic field. The temperature and field dependences of T1 are obtained for the quantum limit and for various mutual locations of the Fermi level and the two lowest spin sublevels of the carriers. It is shown that the deviation of the phonon distribution from thermal equilibrium due to the interaction with the spins of the conduction electrons is small, and a phonon bottleneck should not occur, in contrast with the case of spin‐lattice relaxation of localized spins.
Light Absorption and Dispersion by Impurity Centres at High Concentrations
Authors: Lubchenko A. F. 
Published: July 2007

AbstractAn investigation is made of the optical absorption and the shape of the dispersion lines due to impurity centres in a solid for the case of weak electron‐phonon coupling and high impurity concentration. It is shown that the shape of the absorption lines may be Lorentzian or Gaussian depending upon the magnitude of the shift in the electronic levels of the impurities due the interactions between impurity centres.
Field Emission from p‐Type Germanium
Authors: Fursey G. N. , Sokolskaya I. L. , Ivanov V. G. 
Published: July 2007

AbstractA study is made of the behaviour of field‐emission current‐voltage characteristics in 3.5 Ωcm p‐type Ge emitters, cleaned by field desorption. Nonlinearity of the Fowler‐Nordheim plots, and a contracting field‐emission pattern in the region of slow emission current increase are observed. The dependence of the nonlinear effects on the shape of the emitter and the temperature treatment is studied. The behaviour of the current‐voltage characteristics is also studied for the case where barium and gold films are deposited on the emitter. It is found that coating a field‐emitter with a metallic layer of thickness less than 0.1 monolayers results in the complete removal of the nonlinear effects. A qualitative explanation of these results is given based on the concept of “exhausting” the inversion region near the emitting surface when the emission current is removed.
Peculiarities of the RbMnF3:Nd3+ Crystals Decay Kinetics due to the Migration of Excitation Energy
Authors: Matyushkin E. V. , Kukushkin L. S. , Eremenko V. V. 
Published: July 2007

AbstractThe decay kinetics of the Nd3+ ions luminescence in RbMnF3:Nd3+ crystals are investigated experimentally during excitation into the Mn2+ absorption bands. It is shown that the energy transfer process is preceded by the migration of the excitation energy over the Mn2+ ions in the crystal. A theoretical treatment is given of the diffusion mechanism for this energy migration. The results of the calculation are in quite good agreement with the experimental data.
Wachstum und Struktur dünner, aus schmelzflüssigen Filmen auskristallisierter Germanium‐Kristalle
Authors: Paschoff N. 
Published: July 2007

AbstractFlüssige Germanium‐Filme lassen sich in Schleifen aus dünnem Wolframdraht aufspannen. Bei der Abkühlung kristallisieren die Filme in dünne polykristalline Kristallfolien, für die die Ausbildung einzelner stark abgedünnter Bereiche charakteristisch ist. Die Struktur dieser Bereiche kann optisch und elektronenmikroskopisch untersucht werden. Die geringe Dicke einzelner Bereiche ermöglicht die elektronenmikroskopische Beobachtung bei der relativ niedrigen Betriebsspannung von 65 kV. Die verwendete experimentelle Anordnung zur Herstellung der Kristallfolien wird beschrieben. Der spezielle Wachstumsvorgang dieser dünnen Kristalle wird im Zusammenhang mit dem Kristallisationsprozeß flüssiger Filme diskutiert. Die Mikro‐ und Versetzungsstruktur wurde licht‐und elektronenmikroskopisch untersucht. Hierzu werden einige Beispiele mitgeteilt.