bluuebunny/crossref_metadata_2025_split huggingface dataset:
Der Wärmewiderstand von Kristallen infolge kombinierter Streuung von Phononen and Phononen und an Fehlstellen
Authors: Gruner P. 
Published: July 2007

AbstractMit Hilfe der nichtlinearen Elastizitätstheorie wird der thermische Widerstand bei tiefen Temperaturen infolge der Streuung der Phononen an Phononen und an Gitterfehlern untersucht. Es wird gezeigt, daß die bei der Streuung von langwelligen Gitterschwingungen an Punktfehlern auftretenden Divergenzen in der Wärmeleitfähigkeit χ durch Hinzunahme der Dreiphononenwechselwirkung vermieden. χ verhält sich in diesem Fall bei Temperaturen in der Gegend des flüssigen Heliums wie T−1 und fällt nach hohen Temperaturen hin wie T−α ab (1 < α < 2). Durch zusätzliche Streuung der Gitterwellen an Versetzungen wird diese Temperaturabhängigkeit der Wärmeleitfähigkeit völlig verändert. Bei tiefen Temperaturen ist χ proportional zu T2, durchläuft mit zunehmender Temperatur ein Maximum, um dann nach hohen Temperaturen hin wieder wie T−α abzufallen.
The Effect of s‐p Hybridization on the Band Structure of a Perturbed Linear Chain
Authors: Mourad P. 
Published: July 2007

AbstractThe LCAO approximation is used to study the effects of s‐p hybridization on the band structure of a linear chain in the presence of a localized perturbation. Bound states normally appear at the centre and at the edge of the Brillouin zone; but sometimes hybridization will introduce an intermediary minimum in the band structure and a perturbation will make a bound state leave the band at the minimum. The symmetries of the bound states are examined. The hybrid character of the self‐trapped hole in the VK centre is analysed in this way.
Dislocation Damping of Zone Refined Aluminium Doped with Cu
Authors: Gelli D. 
Published: July 2007

AbstractInternal friction measurements are made at frequencies of a few kHz on well annealed aluminium containing a few p.p.m. of Cu. The results agree with the dislocation damping model [20] which is based on specific assumptions regarding the impurity atmosphere around dislocations. A linearly increasing component is found at the lowest amplitudes which is additional to the parabolic and Granato‐Lücke components previously found. The method of analysing the results, and calculating the parameters, which control the amplitude dependence of the i.f., are defined in detail. A new hypothesis is discussed regarding the shape of the potential valley connected with the dislocation—atmosphere elastic interaction.
Useful Properties of Dark‐Field Electron Images
Authors: Bell W. L. , Thomas G. 
Published: July 2007

AbstractTilting experiments in dark‐field under s ≠ 0 conditions have shown that the image contrast is greatest at the top and bottom surfaces of a foil for s < 0 and s > 0, respectively. This effect has been shown for images of stacking faults or slip traces, inclined dislocations, prismatic loops, precipitates, and small defects observable by strain contrast. This asymmetry is observed only where anomalous absorption is an important factor in controlling the image intensity. The effect can be utilized for obtaining the unique foil orientation without using complicated procedures, such as wedge tilting or X‐ray analysis of the foil in the specimen holder. Once the unique orientation is found, a complete analysis of lattice defects can be carried out with a maximum of two dark‐field photographs. The approximate position of a defect within the foil can also be determined.
The Effect of Solute Concentration on the Formation of Loops in Aluminium‐Magnesium Alloys during Fission Fragment Irradiation
Authors: Vigeholm B. , Makin M. J. 
Published: July 2007

AbstractA study has been made of the effect of magnesium concentration (up to 0.5 at%) on the formation of dislocation loops in aluminium during fission fragment bombardment at 60 °C. Increasing magnesium content reduces the initial rate of increase of the total loop area with dose, but the loop area saturates at a higher level in more concentrated alloys. A concentration as low as 0.02% reduces the initial rate of loop growth by a factor of 4 to 5. Considerable attention has been given to the problems of obtaining accurate measurements of the loop area per unit volume in foils irradiated in the pre‐thinned state, and a number of corrections have been applied. An unusual surface denudation effect is observed. The results are explained in terms of the effect of trapping on the mobility of both the interstitial atoms and the vacancies.
Spin‐forbidden Transitions of Co++ Complexes
Authors: Truţlia AtH. 
Published: July 2007

AbstractA similarity is shown between the spectra of the tetrahedral and octahedral symmetry bivalent cobalt complexes in the 17000 to 20200 cm−1 region. Various interpretations of this similarity are discussed, special mention being made of the positions of the peaks in the corresponding absorption spectra.
Ferromagnetic Resonance and the Ionic Composition of Cobalt Substituted Nickel Ferrite
Authors: Pointon A. J. , Robertson J. M. 
Published: July 2007

AbstractA number of ferrites have been prepared with the nominal composition NiCoxFe2−xO4 with x in the range 0 to 0.03. The ferromagnetic resonance linewidths of these ferrites have been investigated as a function of the conditions of preparation and of the cobalt content. An explanation of the variation of the linewidth, as corrected for the porosity broadening, is discussed in terms of the ionic composition of the ferrite. It is found that in order to obtain a complete explanation it appears necessary to postulate a cation disorder process which gives a positive contribution to the magnetic anisotropy constant K1.
Dynamical Theory of the Images of Microtwins as Observed in the Electron Microscope
Authors: Remaut G. , Gevers R. , Lagasse A. , Amelinckx S. 
Published: July 2007

AbstractIn part II the dynamic two‐beam theory of the images of two superposed parallel coherent walls is presented. This situation occurs at overlapping ferroelectric and antiferromagnetic domain walls, enclosing microtwins characterized by very small twin vectors. In this paper the results deduced from the analytical theory developed in part II are compared with computed fringe profiles which are computed exactly. Very good agreement is found, in particular concerning the nature of the extreme fringes, the spacing and the contrast of the fringes, the mean intensities in the overlap and non‐overlap regions and the geometry of the image of a microtwin with increasing thickness. The results of the theory are illustrated by observations of plate‐ and wedge‐shaped microtwins in barium titanate and cobalteous oxide. It is found that the theoretical predictions about the features and general aspect of the images are supported by these observations.
Piezoresistance of Cadmium Antimonide
Authors: Tovstyuk K. D. , Bercha D. M. , Pankevich Z. V. , Rarenko I. M. 
Published: July 2007

AbstractA theoretical and experimental study is made of the piezoresistance of p‐ and n‐type CdSb. The stress applied along the three crystal axes produces a change in the resistivity of opposite sign. The proposed theory of nonequivalent valley Δ, Λ, and Σ, which follows from the low symmetry of the crystal, explains the observed effects in n‐type CdSb, while a theory involving three nonequivalent shifted valence‐maxima in Γ is in good agreement with the experimental results for p‐type CdSb.
Electron Effective Masses in Heavily Doped n‐Type CdxHg1−x Te
Authors: Mali M. 
Published: July 2007

AbstractElectron effective masses (m*) for n‐type CdxHg1−x Te with x < 0.2 and a free electron concentration N in the range 1.25 to 1.4 × 1018 cm−3 are obtained from measurements of thermoelectric power as a function of magnetic field. The values of m* can be explained on the basis of the energy band model of Groves and Paul with parameters P = 8 × 10−8 eV cm and |E0| ≤ 0.19 eV.
Effect of Excitons on the Scattering of Neutrons by Crystals
Authors: Glauberman A. E. , Ruvinskii M. A. 
Published: July 2007

AbstractAn investigation is made of the magnetic scattering of slow neutrons by non‐localized Mott excitons, and nuclear scattering by polarizing excitons of the Dykman‐Pekar type. It is shown that the effective cross‐sections for magnetic scattering by one exciton are equal, to within at least an order of magnitude, to the corresponding quantities for magnetic scattering by free electrons. The cross‐sections are also comparable with the cross‐sections for scattering by the electrons of impurity centers. The cross‐section for nuclear scattering by a polarizing exciton is of the same order as in the case of a polaron.
Fuchs's Relations in Alkali Halides and Their Application to the Lattice Dynamics of Lithium Fluoride
Authors: Verma M. P. , Dayal B. 
Published: July 2007

AbstractA discussion is given of the work of Lowdin and Lundqvist in which the failure of Cauchy relations in ionic crystals is attributed to the existence of a many‐body potential arising from the overlap of atomic wave functions. It is shown that this many‐body interaction may be represented by a volume force which satisfies Fuchs's relations. A simple model is developed incorporating volume forces phenomenologically. In addition to this, the three‐body interaction introduces an effective charge in to the Coulomb term of the point‐ion model. The model is applied to lithium fluoride and good agreement is obtained between the theoretical and observed values of cv.
Observations des défauts primaires dans les cristaux de fluorure de lithium irradiés par les neutrons thermiques à 77 °K
Authors: Comes R. , Lambert M. , Perret R. , Guinier A. 
Published: July 2007

AbstractOn met en évidence la formation directe, dans des cristaux de fluorure de lithium ayant reçu 1.7 × 1018 neutrons thermiques par cm2, de zones de défauts ponctuels associées aux fissions. Ces zones occupent au moins la moitié du volume du cristal; elles ne sont plus visibles au‐dessus de 110 °K.
Some Transport Properties of Semiconductors under Uniaxial Stress
Authors: Grynberg M. 
Published: July 2007

AbstractThe calculations presented in this paper are valid for the III‐V and II‐VI semiconducting compounds with zinc‐blende structure. Under uniaxial stress the spherical energy surfaces become ellipsoidal. The galvanomagnetic coefficients for n‐type material are calculated following the method described by Żukotyński and Kołodziejczak, and assuming a dispersion law E = E (k,\documentclass{article}\pagestyle{empty}\begin{document}$ \hat \varepsilon $\end{document}) for these bands of the type obtained by Pikus. With the assumption of an isotropic relaxation time, formulae are obtained for the transverse magnetoresistance, thermoelectric power in a magnetic field, and Nernst‐Ettingshausen coefficient. By solving Maxwell's equations with a high‐frequency conductivity tensor, expressions are obtained for the Faraday effect, stimulated birefringence due to free carriers, and plasma frequency under uniaxial stress.
The Curie Temperature of LiNbO3
Authors: Smolenskii G. A. , Krainik N. N. , Khuchua N. P. , Zhdanova V. V. , Mylnikova I. E. 
Published: July 2007

AbstractSingle crystals of LiNbO3 are grown by the flux method. Measurements are made in the temperature range 20 to 1170 °C of the dielectric constant ϵ, dielectric loss and relative thermal expansion ΔLl/l along the polar axis (the three‐fold axis x3) and perpendicular to the glide plane (x1). A sharp maximum in ϵ corresponding to a decrease in volume is observed in the x3 direction at 1140 °C. This temperature is assumed to be the Curie temperature of LiNbO3 which corresponds to the transition from an electrically ordered state (ferro or ferrielectric, rather than antiferroelectric) into a paraelectrical state. The temperature dependences of ϵ and Δl/l below the Curie temperature show several similar anomalies. Some of these anomalies may be due to phase transitions.
Etude et essai d'interprétation du stade III de recuit dans le nickel
Authors: Peretto P. , Dautreppe D. , Moser P. 
Published: July 2007

AbstractUne étude par traînage magnétique du Nickel pur ou dopé irradié aux neutrons et aux électrons à très basse température permet un essai d'interprétation du stade III. Ce stade serait dû à la destruction d'agglomérats d'interstitiels, dont la structure évoluerait au cours du stade II.
Transmission Electron Microscope Study of Natural Radiation Damage in Zircon (ZrSiO4)
Authors: Bursill L. A. , McLaren A. C. 
Published: July 2007

AbstractZircons from different localities show considerable variation in physical properties, and it is generally accepted that these variations are the result of α‐radiation damage due to the presence of radioactive impurities, in particular, uranium and thorium. Transmission electron microscopy has been used to study the radiation damage as a function of α‐dose (D) in a number of zircons. No damage was observed in crystals for which D < 1014 α/mg. However, black spot contrast was observed in crystals for which D = 1015 α/mg. Annealing experiments and electron spin resonance studies suggest that the black spots are due to clusters of oxygen interstitials. Crystals for which D > 1016 α/mg were, on X‐ray evidence, glassy (metamict). However, the electron diffraction patterns and micrographs showed that these crystals were composed of slightly misoriented zircon crystallites about 100 Å in size. After annealing, these metamict crystals showed dislocation loops and networks and the single crystal character was restored. The dislocation loops appear to lie on {101} planes and have Burgers vectors parallel to 〈101〉. Inspection of the crystal structure of zircon suggests that this is a likely slip system for zircon. Both interstitial and vacancy dislocation loops were observed. These results suggest a mechanism for the transformation from normal to metamict zircon and this is discussed.
Specific Electrical Conductivities of Tantalum‐Molybdenum Alloy Single Crystals
Authors: van Torne L. I. 
Published: July 2007

AbstractThe specific electrical conductivities of electron beam zone refined tantalum‐molybdenum alloy single crystals were measured at 273, 77, and 4.2°K. It was assumed that the Fermi surface of the alloys is an order of magnitude less than that corresponding to a Fermi sphere and the total scattering cross section behaves like 2π (√2 ΛF)2, where ΛF is the wavelength of electrons at the Fermi surface. Under these assumptions, the calculated electrical conductivities showed good agreement with the observed conductivities at 4.2°K for tantalum rich alloys. The divergence between calculated and observed conductivities in molybdenum rich alloys is attributed to the contribution of holes to the conductivity.
Propriétés diélectriques du sulfate de glycocolle
Authors: Telle F. , Lauginie P. 
Published: July 2007

AbstractIl est possible d'établir entre le champ électrique E et la polarisation P parallèle à l'axe binaire une relation du type E = a P + b P3 + c P5 + d P7 qui rend compte à la fois des valeurs de la constante diélectrique et de la polarisation spontanée. Les coefficients a, b, c, d varient généralement en fonction de la température et a n'est pas une fonction linéaire de la température au‐dessous du point de transition.
Superconductivity in the Close‐packed Intermediate Phases of the VIr, NbIr, NbRh, TaRh, NbPt, TaPt, and Other Related Systems
Authors: Sadagopan V. , Gatos H. C. 
Published: July 2007

AbstractThe superconducting behavior of various close‐packed low symmetry intermediate phases in the VIr, NbIr, NbRh, TaRh, NbPt, TaPt, HfRh, and HfIr systems was investigated. By considering the σ‐phase as a close‐packed phase, a smooth relationship was found between its superconducting transition temperature (Tc) and those of the other close‐packed phases (of a given system) on the one hand and their composition on the other. In each system the σ‐phase exhibited the highest Tc. The normal behavior of the close‐packed phases of the pseudobinary systems “NbRu3”NbPt3. NbIr3NbPt3, “NbOs3”NbPt3, and ZrPt3NbPt3 down to 1.6°K is considered consistent with the model of Gusman and Brout [1].
Isomerieverschiebung der 23,8 keV‐γ‐Linie von 119Sn in verschiedenen Legierungsphasen
Authors: Pobell F. 
Published: July 2007

AbstractEs wird über Messungen der Isomerieverschiebung der 23,8 keV‐γ‐Linie von 119Sn in Legierungen von Zinn mit sechs seiner Nachbarn im Periodensystem der Elemente berichtet. Die Messungen wurden über den gesamten Konzentrationsbereich der Legierungen durchgeführt. Innerhalb einer einzelnen Phase ist die Isomerieverschiebung konstant. Der Übergang zu einer neuen Phase ergibt eine starke Änderung der s‐Elektronendichte im 119Sn‐Kern. Die Ergebnisse werden diskutiert und mit Messungen der Knight‐Verschiebung verglichen.
Modifizierte Bloch‐Wellen und ihre Anwendung auf den elektronenmikroskopischen Beugungskontrast von Gitterfehlern
Authors: Wilkens M. 
Published: July 2007

AbstractDie von Penning und Polder [6] und von Kato [8] eingeführten modifizierten Bloch‐Wellen werden auf die Darstellung des elektronenmikroskopischen Beugungskontrastes angewandt. Man erhält Differentialgleichungen, die die von den Gitterstörungen induzierte Streuung zwischen den modifizierten Bloch‐Wellen beschreiben. Die Störparameter der Gleichungen sind proportional zu den zweiten Ableitungen der Verschiebungskomponenten, d. h. proportional zu den Gitterkrümmungen und umgekehrt proportional zu der dem Beugungsvektor zugeordneten Fourier‐Komponenten des Potentials. Die Gleichungen ergeben eine klare Trennung zwischen Phasenkontrast und Streukontrast, die beide auf physikalisch wesentlich verschiedenen Ursachen beruhen und beide zum elektronenmikroskopischen Beugungskontrast von Gitterfehlern beitragen.
Observation des domaines en rubans dans les lames minces de fer pur par microscopie électronique
Authors: Bourret A. , Dautreppe D. 
Published: July 2007

AbstractDes observations de domaines magnétiques dans le fer pur aminci sont faites par microscopie électronique (méthode de Lorentz). Les lames ont une orientation préférentielle (111). A l'intérieur des domaines on observe une structure en rubans (stripe domain) pour des épaisseurs supérieures à 1300 Å. Ces rubans sont parallèles à l'aimantation moyenne de chaque domaine. Un modèle simple d'oscillation de l'aimantation est proposé et analysé.
Effects of Fast Neutron Irradiation and of Impurities on the X‐Ray Intensities Diffracted by Germanium and Silicon Crystals
Authors: Colella R. , Merlini A. 
Published: July 2007

AbstractAn investigation is made of the effects of fast neutron irradiation and of impurities on the X‐ray diffraction intensities of Ge and Si crystals having low dislocation densities. Monochromatic CuKα and MoKα radiations are used in both the transmission and reflection geometries. Appreciable increases of the integrated intensities are found for Si crystals irradiated with a dose of 3 × 1020 nvt. These increases are greatest if transmission geometry and MoKα radiation (thin crystal case) are used. There is, however, no variation in the diffraction intensities in anomalous transmission. The irradiation is found to have no effect on the diffraction intensities in Ge crystals irradiated up to 3 × 1020 nvt. With Si crystals doped with boron up to a maximum atomic fraction of 1.3 × 10−3 the intensities increase with increasing concentration of the doping element in the transmission geometry, when MoKα radiation is used. In anomalous transmission the intensities vary greatly in different regions of the most heavily doped Si crystal.
A New Manifestation of Magnetic After‐Effect
Authors: Knowles J. E. , van Groenou A. Broese 
Published: July 2007

AbstractMinor hysteresis loops of magnetite were observed at room temperature. Immediately after demagnetization the loop was of the Rayleigh type, but changed with time, while a small alternating field was present into a very rectangular loop which disappeared abruptly after one hour. It is shown that if the amplitude of the wall displacement is large compared to the wall thickness, then instead of the wall forming a single potential well as described by the existing theory of magnetic after‐effect, it will form two adjacent wells, which give rise to the above phenomenon.
Transverse Gain in GaAs Laser Structures
Authors: Burrell G. J. , Moss T. S. , Hetherington A. 
Published: July 2007

AbstractGain measurements are reported for radiation of wavelength 8466 Å propagating in a direction perpendicular to the junction of a GaAs injection laser operated at 80 °K. These results, used in conjunction with measurements of spontaneous emission, show that a gain of 2.3% is achieved at 7000 A/cm2. In thermal equilibrium 0.78% of the transmitted radiation is absorbed in traversing the active region, 135 A/cm2 being required to off‐set this loss before net gain is obtained.
Influence de la structure locale de l'anisotropie magnétique induite sur la dispersion de l'aimantation dans les couches minces de permalloy
Authors: Roth M. 
Published: July 2007

AbstractOn calcule la dispersion de l'aimantation d'un film mince polycristallin de permalloy en tenant compte du fait que, par traitement dans un champ magnétique uniforme, l'anisotropie uniaxiale induite due à l'ordre directionnel et à la déformation imposée par le support est différente dans chaque cristallite car elle dépend de l'orientation cristallographique de celui‐ci. On trouve qu'en général la dispersion résultante est supérieure à celle que l'on obtient en ne considérant que l'effet de l'anisotropie magnétocristalline, et que contrairement à ce qu'il est admis couramment, la dispersion ne décroit pas de façon monotone quand l'énergie Ku d'anisotropie uniaxiale augmente mais commence par décroître (pour des valeurs de Ku plus petites que l'énergie d'anisotropie magnétocristalline) jusqu'à un minimum puis augmente avec Ku.
The Ferromagnetic Domain Structure of Thin Single‐Crystal Fe Platelets in an External Field
Authors: Gemperle R. 
Published: July 2007

AbstractThe domain structure of small iron single‐crystals in the shape of thin rectangular platelets is studied by means of a colloid technique during magnetization. The observations indicate that the demagnetizing field of the sample is formed by charges on the domain walls. Changes in the domain structure are compared with a magnetization curve obtained by measuring the areas of individual domains.
Origin of the Condenser Photo‐E.M.F. in Semiconductors and of the Photoinduced Change in the Contact Potential
Authors: Akimov I. A. , Meshkov A. M. , Terenin A. N. 
Published: July 2007

AbstractThe sign of the surface charge and its effect on the magnitude of the magnitude of the photo‐response are investigated for high‐ohmic inorganic and organic semiconductors by using Bergmann und Kelvin condensers. An explanation is given of the origin and polarity of the photo‐response, and the changes in its spectral distribution. The results indicate the reliability of condenser methods for determining the sign of photo‐excited carriers in the absorption band of a semiconductor. The spectral phenomena occurring at the band edge can successfully be used to study the surface states of the semiconductor.
Heliconwellenausbreitung in InSb und InAs
Authors: Flietner H. , Kliefoth K. 
Published: July 2007

AbstractDie Heliconausbreitung wird bei 24,8 GHz und Zimmertemperatur für InSb und InAs nach einer Resonanzmethode und einer Phasenvergleichsmethode untersucht. Die für isotrope effektive Masse und energieunabhängige Relaxationszeit sich ergebene Dispersionsrelation wird bestätigt.
Magnetic Properties of Eu3O4
Authors: Wang F. F. Y. 
Published: July 2007

AbstractA new Eu3O4 preparation method is described. Eu3O4 is produced by the solid state reaction between Eu and Eu2O3. Static magnetic susceptibility measurements were made by the Faraday method from 6 to 300°K. Eu3O4 was found to be ferrimagnetic with a Curie point of 77 °K.