bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasonic Velocity and Attenuation in Alkali Halides Containing CN− I. Experimental Results
Authors: Byer N. E. , Sack H. S. 
Published: July 2007

AbstractThe ultrasonic velocity and attenuation were measured in KCl, KBr, KI, and NaCl containing CN− as a function of acoustic mode, temperature, concentration, frequency, plastic deformation, and static bias stress. The results are not compatible with stress ordering of an elastic dipole tensor represented by an ellipsoid of rotation with CN− axes having 〈100〉 equilibrium positions, as had been inferred from other measurements. A thermally activated relaxation peak was observed for a CN− dimer with a barrier height of 0.008 eV. In NaCl the CN− reorients by thermal activation over a 0.035 eV barrier as opposed to the tunneling in the potassium halides.
Ultrasonic Velocity and Attenuation in Alkali Halides Containing CN− II. Theoretical Interpretation
Authors: Byer N. E. , Sack H. S. 
Published: July 2007

AbstractThe experimental results presented in Part I are interpreted in terms of the continuum elastic dipole theory, assuming that asymmetric lattice relaxation perpendicular to the CN− axis results in a dipole tensor with three different principal axes, one of which is the CN− axis. The equilibrium positions are [001], [110], and [110] and their equivalents. Acoustic interaction with hindered rotor states was also observed.
Zero‐Phonon Transitions of Eu++ ‐ and Sm++ ‐Doped Alkali Halides
Authors: Baldini G. , Guzzi M. 
Published: July 2007

AbstractThe theory of the electron‐phonon coupling for impurity centres in ionic crystals is reviewed in order to point out the most significant parameters involved in the optical properties of the zero‐phonon lines. The absorption and emission spectra of alkali halides doped with Eu++ and Sm++ have been measured for temperatures ranging from 15 up to 175°K. In general the analysis of the experimental data agrees fairly well with the theory. The Huang‐Rhys factor has been determined and also the effective frequencies which are responsible for the thermal behaviour of the spectra. However the electron‐phonon interaction alone has been found not to be sufficient in order to explain the thermal dependence of the zero‐phonon line strength and an additional mechanism for its thermal de‐excitation has been proposed.
Intersystem Crossing and Multiple Tunnelling
Authors: Osherov V. I. 
Published: July 2007

AbstractThe problem of non‐adiabatic tunnelling in the system of two coupled parabolic terms interacting with the environment has been solved. The model is applied to intersystem crossing in the simple centre of luminescence. The role of multiple passage through the region of term interaction has been cleared up. Criteria of applicability depending on the width‐level splitting ratio have been ascertained.
Incorporation of Antimony into the Barium Titanate Lattice
Authors: Schmelz H. 
Published: July 2007

AbstractThe interest in the incorporation of Sb into the BaTiO3 lattice is based above all on the fact that small additions of Sb (below 0.2 wt% Sb2O3) yield semiconducting ceramics with a resistivity anomaly at the Curie point. Larger amounts of Sb, however, result in insulating samples. This is caused by a different kind of incorporation. In the range of high concentration only a composition as BaO + (1 − x) · TiO2 + x · 1/2 Sb2O3 (for x between 0 and 0.1) yields ceramics which show no crystalline phases other than the perovskite one. This and the structure factors determined by neutron diffraction provide a definite proof that Sb occupies Ti sites. By means of combined electron‐microprobe and X‐ray analysis it is also shown that in the case of excess TiO2 in the BaTiO3 solid solution, Sb partly substitutes Ba sites.
Indirect Energy Gap in GaSe and GaS
Authors: Aulich E. , Brebner J. L. , Mooser E. 
Published: July 2007

AbstractOptical absorption measurements on thick monocrystalline samples of GaSe1−xSx show that in these mixed crystals the lowest energy gap is indirect in the complete range 0 ≦ x ≦ 1. These results are contrary to earlier reports which indicate that GaSe is a direct gap semiconductor. In the case of GaS the absorption spectra allow a tentative identification of the phonons involved in the indirect transition.
The Structure of High‐Angle Grain Boundaries in Aluminium
Authors: Levy J. 
Published: July 2007

AbstractA transmission electron‐microscopy study of high‐angle grain boundaries has been made. When thin foils are cut in precisely oriented bicrystals of aluminium, some details of the grain‐boundary structure appear. Micrographs of symmetrical tilt boundaries around [001] show linear defects parallel to the tilt axis. Their properties are tightly bound to the geometry of the bicrystal: this provides a good support to the idea of a transitional lattice as a structure of a high‐angle boundary. A theoretical interpretation of these observations is developed essentially on geometrical considerations.
A Calculation of the Electronic Properties of the F′ Center in KCl
Authors: Strozier J. A. , Dick B. G. 
Published: July 2007

AbstractThe electronic properties of the F′ center in KCl were calculated by a variational procedure using a Hamiltonian which approximates the effects of polarization and correlation. The trial functions were orthogonalized to nearest and next nearest neighbor core functions. Values of −1.05 eV for the F′ maximum absorption and −0.49 eV for the thermal dissociation energy were obtained. By approximating the continuum states of the ionized F′ center by eigenstates of an appropriately chosen spherical square well, the shape of the F′ center by eigenstates of an appropriately chosen spherical square well, the shape of the F′ band itself was also calculated and the results compared with Lütys experimental data of F′ absorption in KCl. Fair agreement was obtained.
Infrared Absorption by Local Vibrational Modes of Boron Impurities in Germanium
Authors: Nazarewicz W. , Jurkowski J. 
Published: July 2007

AbstractLocal modes of boron in germanium have been observed by infrared absorption measurements in the range from 480 to 630 cm−1 at 195 and 295°K. Lithium has been used as a compensating donor impurity. The absorption spectrum contains three pairs of bands which are attributed to local modes of boron on the basis of the isotopic shifts observed. One of these pairs is associated with unpaired (isolated) boron and two others with boron in paired configuration (with lithium), as was predicted theoretically. A comparison of our data with those already known for silicon is given.
Zur Theorie des Ferromagnetismus magnetisch anisotroper Schichten mit kubischer Kristallstruktur. III. Berechnung der räumlichen Magnetisierungsverteilung und der mittleren Magnetisierung in einer Eisenschicht mit (100)‐Oberflächenorientierung
Authors: Haubenreisser W. , Brodkorb W. , Corciovei A. , Costache G. 
Published: July 2007

AbstractAuf der Grundlage vorangegangener Arbeiten wird mit der Methode der Greenschen Funktion in einer modifizierten RPA die Abhängigkeit der mittleren Magnetisierung und der räumlichen Magnetisierungsverteilung in einer Fe‐Γ(100)‐Schicht von der Temperatur und der Atomlagenzahl numerisch berechnet. Die numerischen Ergebnisse verschiedener Theorien werden miteinander verglichen.
Topographic Study of 180° Domains in Triglycine Sulfate
Authors: Petroff J. F. 
Published: July 2007

Abstract180° domain walls have been observed in TGS by X‐ray topography and two types of deformation revealed around these walls. A theoretical model has been used to calculate the wall thickness. There is good agreement between theoretical and experimental results. Domain nucleation and growth have been studied under an applied field by the same technique.
Capacitances and Differential Negative Resistances of MIM Structures
Authors: Bernard J. , Delacote G. , Mentalecheta Y. 
Published: July 2007

AbstractA study has been made of the oxide thickness dependence of the capacitance and the current—voltage characteristics (at 10−5 Torr) of the structures AlAl2O3Au. The thicknesses varied from 25 (oxide formed at air) to 500 Å. The value of the apparent dielectric constant decreases for very thin oxide films. Differential negative resistances have been observed for all diodes. The voltage for the minimum current and the current and the current after the minimum increase linearly with the thickness of the oxide. The results are explained by the existence of a high resistance domain with a thickness of about 10 to 20 Å at one of the metal oxide interfaces, probably the interface AlAl2O3. The decrease of the current is perhaps caused by an increase of the thickness of the domain. Structures with thicknesses of oxide e > 400 Å show a broad current maximum which is sometimes splitted in two maxima.
Theoretical Studies on the M′‐Centre in Alkali Halide Crystals
Authors: Evarestov R. A. 
Published: July 2007

AbstractThe results of the theoretical study of the electronic states of the M′‐centre in alkali halides are reported. No empirical parameters are used in this calculation. – The electronic core polarization is taken into account (within the limits of model of the polarizable point ion lattice), and is found to be essential for the charged M′‐centre. The results of the calculation are in good agreement with the experimental data for KCl and KBr crystals and can be considered as a thoretical confirmation of the F‐model of the M′‐centre.
Effects of Dislocation Distribution on the Specific Heat of Deformed Type II Superconductors
Authors: Barbee T. W. 
Published: July 2007

AbstractThe effects of dislocation distribution on the mixed state specific heat of deformed Type II superconductors are considered. Calculations based on a simple model are shown to predict behavior in agreement with reported experimental results for deformed niobium if an internal variation for ϰ of 0.4 caused by dislocation distribution is assumed. The implications of this result for fluxoid pinning in deformed Type II superconductors are discussed. Applications of measurements of the mixed state specific heat of Type II superconductors to the study of imperfections and imperfection distribution are also discussed.
Thermal Expansion of Silicon and Zinc Oxide (I)
Authors: Ibach H. 
Published: July 2007

AbstractA new expansion cell for the three‐terminal capacitance method is developed. Length changes in the order of 10−9 cm can be measured at samples of only 4 mm. At first the expansion coefficient of silicon (reference material) is investigated in detail from 20 to 300 °K. The work is completed by interferometric measurements up to 800 °K. The temperature dependence of the expansion coefficient is discussed using the thermal equation of state. Furthermore conclusions are drawn concerning the contributions of different phonon branches and compared to calculations on the basis of well‐known models.
Infrared Absorption by Localized Vibrations of H− and D− Ions in NaF and LiF Crystals
Authors: Dötsch H. 
Published: July 2007

AbstractThe infrared absorption due to localized vibrations of H− and D− ions in NaF and LiF is measured between 20 and 300 °K. The oscillator strengths are temperature independent. Measurements with uniaxial pressure show that the frequency of the local mode in NaF:H− is shifted by lattice distortions of the symmetry of Γ and Γ but not of Γ. In NaF:D−, LiF:H−, and LiF:D− two‐phonon decays are allowed resulting in relatively large halfwidths at low temperatures. In NaF:H− a two‐phonon decay is not possible and the halfwidth becomes smaller than the minimum spectral slit width of the grating spectrometer. The temperature dependence can be described by a scattering process in NaF:H− and by a composition of a scattering process with a two‐phonon decay process in the other systems. The anharmonic frequency shift is calculated to a first approximation. In a simple density approximation the side band spectra can be described better by anharmonicity than by nonlinear dipole moments.
Stress‐Induced Dichroism in Tl+‐Doped Potassium Halides
Authors: Bimberg D. , Dultz W. , Gebhardt W. 
Published: July 2007

AbstractChange of absorption under uniaxial compressive stress has been investigated in KCl: Tl+ and KBr: Tl+ on the A‐band and in KI: TI+ on the A‐ and B‐bands at 77 and 20 °K. A. light modulation method has been applied with a rotating polarizer. The data were analysed by the method of moments and show a red shift of the bands with stress and polarization parallel to the [100] axis and a blue shift of the bands with stress and polarization parallel to the [110] axis. From these data it is concluded that the Jahn‐Teller distortion of the Eg mode of the A‐excited state leads to a compression of the impurity octahedron.
Internal Friction in AlAg Alloys
Authors: Schoeck G. , Bisogni E. 
Published: July 2007

AbstractA study has been made of an internal friction peak which occurs due to the precipitation of the γ′ phase from supersaturated AlAg alloys. From the known crystallographic relations and using electron transmission observation from the literature on the morphology of the precipitates, it is shown that the peak is caused by the diffusion controlled relaxation of partial dislocations surrounding the precipitates.
Capacitance—Voltage Relations of Schottky and p—n Diodes in the Presence of both Shallow and Deep Impurities
Authors: van Opdorp C. 
Published: July 2007

AbstractIf at the lightly doped side of an abrupt junction both shallow and deep impurities of the same kind are present, the slope of a low‐frequency C−2 vs. V plot is proportional to the total concentration of these impurities. The value of the voltage Ve as found by extrapolating C−2 to zero depends on the individual concentrations and depths of the two kinds of impurities. A simple expression for Ve is derived. The same is done for a diffused graded junction with both shallow and deep impurities in the starting material. If the depths of the impurities are known, the two concentrations can be found separately.
Modulation and Excitation of the Infrared Luminescence of ZnS(Cu) by Electric AC Fields
Authors: Gumlich H.‐E. , Moser R. , Neumann E. 
Published: July 2007

AbstractThe infrared luminescence of ZnS(Cu) due to internal transitions within the 3d9 configuration of Cu2+ ions excited by radiation may be modulated by electric ac fields (field modulation). The experimental data lead to the conclusion that the modulation of the emission is caused by field‐induced density oscillations of free electrons within the ZnS lattice. The infrared Cu2+ emission may also be obtained without exciting radiation by the action of the electric ac field (electroluminescence). The infrared electroluminescence may be stimulated or quenched by additional irradiation.
Supertransferred Hyperfine Field for Lu in YbIG
Authors: Wäppling R. , Karlsson E. , Johansson K. 
Published: July 2007

AbstractA supertransferred hyperfine field and its temperature dependency was observed for a diamagnetic Lu impurity introduced into Yb‐sites in YbIG. The contribution from the Yb sublattice is fairly large and the hyperfine field follows the total magnetization rather than any of the sublattice magnetizations. As intermediate results it has been verified that the electronic ground state of a daughter atom (Lu) of a radioactive decay in an insulating medium is reached in a time short compared to 10−9 s and that the nuclear magnetic moment of the 114 keV state in 175Lu is (1.99 ± 0.15) μN.
Sensitivity of Many‐Beam Electron Microscope Images to the Form of Absorption and Extinction Parameters
Authors: Metherell A. J. F. , Fisher R. M. 
Published: July 2007

AbstractThe sensitivity of electron microscope image intensity profiles to the form of the absorption and extinction parameters has been analyzed for many‐beam diffraction conditions which predominate at high voltage for most metals. The results show that the profiles are most sensitive to the extinction parameter which must be known to better than 5% if good agreement with experiment is to be obtained. It appears that the form of the absorption parameters has little influence on the intensity distributions of n‐beam profiles, especially for medium atomic number elements such as copper.
Volume and Surface Magnon States in Semi‐Infinite Ferromagnetics
Authors: Stojanović S. , Tošić B. S. 
Published: July 2007

AbstractIn this work the theory of surface and volume magnon states in a semi‐infinite ferromagnetic with simple cubic lattice is formulated in the second quantization representation. The volume and surface phonon states as well as the Hamiltonians of the magnon interactions with the volume and surface phonons are also formulated. The probabilities for surface annihilation of volume magnons due to magnon‐phonon interaction are investigated. It is shown that this process is more probable in the case that surface phonons participate in the process.
Nuclear Spin‐Lattice Relaxation in NH4PF6 · NH4F
Authors: Tōdō I. , Tatsuzaki I. 
Published: July 2007

AbstractNuclear magnetic resonance spectra and nuclear spin‐lattice relaxation times of 1H and 19F in NH4PF6 · NH4F have been studied. The linewidths of both nuclei did not change between room temperature and 77 °K. No anomaly in the relaxation time of 1H has been found at both phase transition temperatures. However, an anomaly in the relaxation time of T and in the correlation time τF of 19F, which were assumed to be due to the random reorientational motion of the PFion, were found at both phase transition temperatures. — The results suggest that the antiferroelectric phase changes in NH4PF6 · NH4F are accompanied by a change in the lattice structure which alters the potential in which the PFion moves.
Das Flußliniensystem axial magnetisierter zylindrischer Supraleiter zweiter Art
Authors: Essmann U. , Träuble H. 
Published: July 2007

AbstractAls Grenzfälle der Flußlinienanordnung realer Supraleiter 2. Art mit hohen χ beobachtet man ein regelmäßiges Dreiecksgitter bei hoher Flußliniendichte und eine flüssigkeitähnliche Struktur bei niedriger Flußliniendichte. Infolge der Anwesenheit von strukturellen Inhomogenitäten, wie z. B. Versetzungen, in den Proben hängen die Dichte und die Anordnung der Flußlinien vom Radiusvektor der Proben ab. Die beobachteten Flußgradienten werden diskutiert und versetzungstheoretisch beschrieben. — Die Fehlordung im Flußliniengitter wird mit abnehmender Flußliniendichte größer. Bei den hier untersuchten Pb‐In Proben geht das Flußliniensystem für Bloc < 30 G in eine Flüssigkeitsstruktur über. Diese Erscheinung wird auf die Wechselwirkung der Flußlinien mit Haftstellen im Metallgitter zurückgeführt. Aus den Abständen isolierter Flußlinien vom Rand des Flußliniensystems wird die Haftkraft für einzelne Flußlinien abgeschätzt.
The Electron Microscopic Observation of Mechanical Twins in Gadolinium
Authors: Kumar J. , Srivastava O. N. 
Published: July 2007

AbstractMechanical twinning in gadolinium has been observed using an electron microscope. The analysis of electron diffraction patterns revealed that the twinning elements are K1 = K2 = (1012) and η1 = η2 = [1011]. The possible mechanism of genesis for these twins are investigated. It is found that the twins are nucleated due to thermal stresses set up in the films as a result of electron irradiation. There is no evidence for the pole dislocation mechanism to be operative in the present case, instead, the observations suggest that the twin formation is in accordance with the Bell‐Cahn mechanism.
Dislocation Helices in Molybdenum
Authors: Becker C. , Pegel B. 
Published: July 2007

AbstractNumerous large helical dislocations with lengths up to 4 mm and diameters between 10 and 130 μm have been observed in molybdenum by means of X‐ray topography. From these observations an equilibrium vacancy concentration of about 3 × 10−6 at 2000 °C in molybdenum is derived.
Stage I Recovery of Resistivity in Electron‐Irradiated Silver and Gold. I. Silver
Authors: Wiffen F. W. , Snead C. L. , Kauffman J. W. 
Published: July 2007

AbstractThe stage I recovery of silver has been investigated by resistivity measurements and isochronal annealing of 99.999% purity silver after irradiation with 2.0 MeV electrons at liquid helium temperature. Detailed annealing schedules for several different initial defect concentrations and for a radiation doped run confirmed the general similarity in the stage I recovery behavior of silver and copper and revealed the systematic differences between the two metals. Silver shows several first‐order recovery substages and shows a small component of recovery due to free interstitial migration near 31 °K. The total amount of recovery in stage I was found to be a sensitive function of defect concentration, for small defect concentrations, with the amount of recovery increasing for increasing initial damage over the range investigated. The observed results are explained in terms of a “competitive process, one interstitial model” with most of stage I recovery due to close pair recombination. The fate of freely migrating interstitials is governed by the relative importance of impurity trapping, vacancy annihilation, and interstitial complex formation. The importance of each of these processes depends upon the initial defect concentration, impurity concentration, and the effectiveness of vacancies and interstitials for capturing interstitials. The higher probability of dimer formation in silver than in copper is a result of the larger radius of the interstitial strain field in silver and results in the smaller amount of stage I recovery, the smaller size of IE, and is a major contributor to the observed lack of dose dependence in silver.
Injected Electron Currents Through Insulators
Authors: Christov S. G. 
Published: July 2007

AbstractThe previously presented unified theory of field and thermionic emission is extended to electron emission into dielectrics, including thin films between two metal electrodes. The current equations are derived under the assumption of a parabolic energy—momentum dependence and convenient barrier shape approximations for various thicknesses of the insulating layer, but the general method is used in the case of any arbitrary barrier shape. Both cases of equal and unequal effective electron masses in the insulator and the metals are considered. The current expressions obtained are applicable to the whole range of fields and temperatures between the limits of thermionic and field emission.
Diffusion of Inert Gases in Copper
Authors: Rickers G. , Sørensen G. 
Published: July 2007

AbstractThe ion bombardment technique was used to study inert gas diffusion in polycrystalline copper. Radioactive single charged ions of krypton and xenon were implanted in copper at energies between 20 and 450 keV. The ion‐doped specimens were thermally annealed, and the influence on gas release of implanted ions, implantation energy, and dose was investigated. A new chemical sectioning technique was used to measure the integral distribution of the implanted ions before and after thermal annealing. By correlating the measurements of fractional gas release with those of diffusion profiles, it was possible to obtain a model for inert gas diffusion in copper.
Internal Friction Due to Precipitation
Authors: Schoeck G. 
Published: July 2007

AbstractInternal friction can be caused by precipitates if they produce internal strains, have elastic moduli different from the matrix or if they have incoherent or semicoherent interface boundaries. By considering the interaction energy with an externally applied stress field, the possible internal friction effects are discussed. It is shown that an internal friction peak can only be caused by interface relaxation in semi‐coherent or incoherent interface boundaries.