bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy of hexagonal dislocation loops
Authors: Liu G. C. T. , Li J. C. M. 
Published: July 2007

AbstractThe elastic strain energy of an elongated hexagonal dislocation loop is calculated from the stress field of dislocation segments using isotropic elasticity theory. Energies of rhombus dislocation loops and rectangular dislocation loops are presented as limiting cases. The equilibrium shapes of these loops are discussed in the light of experimental results.
Measurements of the anisotropy of the dislocation resistivity in Au, Ag, and Cu
Authors: Yoshinaga H. 
Published: July 2007

AbstractThe anisotropic resistivity of dislocations produced by deformation is measured in high purity Au, Ag, and Cu single crystals at liquid helium temperature. Resistivities along the direction perpendicular to the slip plane are found to be greater than those parallel to the slip plane. The ratio Δϱ⟂/Δϱ∥ (where Δϱ⟂ and Δϱ∥ are the resistivity increments along directions perpendicular and parallel to the slip plane, respectively) is nearly constant in the easy glide region (stage I). For the crystals of Au, Ag, and Cu used here this ratio is 2.28, 2.88, and 2.32, respectively, while in the rapid‐hardening region (stage II) this ratio decreases rapidly to unity with increasing deformation. Comparing these values with the theory of Seeger and Bross, it is concluded that the stacking‐fault resistivity of an extended dislocation is relatively small compared with the resistivity due to the strain field around an edge dislocation and amounts to only 3% of the strain field resistivity in Au, 15% in Ag, and 12% in Cu.
Effect of zero‐point energy on the specific heats of solidified neon and xenon
Authors: Gupta N. P. , Dayal B. 
Published: July 2007

AbstractThe specific heats of neon and xenon are calculated from a study of their lattice vibrations. The effect of zero‐point energy is included by an iterative method and a Buckingham exponential potential is used. The calculated and experimental values of Cv agree well for xenon but not so well for neon. It is suggested that the interatomic forces in neon are similar to those in helium and that a Buckingham potential, which is applicable to solids formed from heavy rare gases, is inapplicable to solid neon.
Pseudo‐abrupte legierte p–n‐Übergänge in GaP
Authors: Jung M. 
Published: July 2007

AbstractKapazitätsmessungen an legierten p–n‐Übergängen in GaP zeigen Ergebnisse, die mit der Vorstellung vom abrupten p–n‐Übergang nicht vereinbar sind. Das Modell eines pseudoabrupten Übergangs deutet die Ergebnisse. Die Hälfte der untersuchten Übergänge erweist sich als pseudo‐abrupt. Es ist nicht möglich, aus Kapazitätsmessungen die Diffusionsspannung an einem p–n‐Übergang mit räumlich konstanten Störstellendichten zu bestimmen, wenn nicht sichergestellt ist, daß dieser Übergang ideal abrupt ist.
Experimentelle Bestimmung der maximalen Austrittstiefen monoenergetischer Sekundärelektronen
Authors: Mayer H. , Hölzl J. 
Published: July 2007

AbstractDurch Messung der Energieverteilung der Sekundärelektronen, die man erhält, wenn Primärelektronen der Energie VP = 200 eV auf einen Pt‐Träger treffen, der mit K‐Schichten jeweils bekannter, von Null an zunehmender Dicke bedampft wird, kann die maximale Austrittstiefe monoenergetischer Sekundärelektronen als Funktion ihrer Energie erhalten werden. Die gewonnene Kurve zeigt zwei ausgeprägte Minima mit Austrittstiefen von nur wenigen Atomlagen, die mit den charakteristischen, durch die Anregung von Plasmonen verursachten Energieverlusten von Elektronen in Kalium in Zusammenhang gebracht werden können. Die Ergebnisse stimmen gut mit photoelektrisch gemessenen Elektronenaustrittstiefen überein.
Die innere Dynamik der Tieftemperaturphasen des Molekülkristalls CH4
Authors: Dorner B. , Stiller H. H. 
Published: July 2007

AbstractFestes Methan zeigt zwei Umwandlungspunkte (90,67 °K > T > 20,55 °K Phase α, 20,55 °K > T > ca. 8 °K Phase β, T < ca. 8 °K Phase γ). Mit der inversen Filtermethode werden die Energieverteilungen von in festem Methan bei 6,5 °K (Umwandlungsgebiet β‐γ) und 2,7 °K (γ‐Phase) gestreuten langsamen Neutronen gemessen. Die Ergebnisse werden mit denen von früheren, bei 18 °K (β‐Phase) ausgeführten Messungen verglichen. Das für die γ‐Phase ermittelte Spektrum bestätigt qualitativ ein von James und Keenan unter der Annahme von Oktopol‐Oktopol‐Wechselwirkungen ausgerechnetes Strukturmodell. Für die Phase β konnte ein Vergleich im einzelnen nicht angestellt werden. Im Temperaturbereich des Übergangs zwischen der β‐ und der γ‐Phase können Teile der beobachteten Frequenzverteilungen als Bestandteile der Spektren der Phasen β und γ gedeutet werden, andere Teile sind dagegen von den Spektren der beiden reinen Phasen verschieden. Der aus der Frequenzverteilung in der γ‐Phase berechnete Debye‐Waller‐Faktor wie auch der mit elastischer Neutronenstreuung in der γ‐Phase gemessene Debye‐Waller‐Faktor weisen auf große Protonen‐Auslenkungen hin.
Effect of concentration on light absorption and dispersion by impurity centres in the case of weak electron—phonon coupling
Authors: Lubchenko A. F. , Dudkin S. I. 
Published: July 2007

AbstractAn investigation is made of the dependence of the absorption and dispersion spectra due to impurities in a solid on the impurity concentration. The electron‐phonon coupling is considered to be weak and a Green's function method is used. It is shown that at low concentrations the halfwidth and spectral position of the zero‐phonon line vary linearly with concentration and a similar behaviour is found for the corresponding dispersion curve.
Radiation effects in pile‐irradiated LiF crystals
Authors: Shvarts K. K. , Vitol A. Ya. , Podin A. V. , Kalnin D. O. , Ekmanis Yu. A. 
Published: July 2007

AbstractA study is made of EPR, optical absorption (in the range 2 to 6 eV) and density variation of LiF crystals that have been irradiated in a reactor with doses up to 1019 neutrons/cm2. In the irradiated crystals the main paramagnetic defects are F‐centres. Some conclusions are drawn as to irradiation‐induced expansion processes and the formation of colour centres. Some details of the aggregation process of F‐centres are clarified by thermal annealing of the irradiated crystals.
Heat conductivity study of GaSe monocrystals
Authors: Guseinov G. D. , Rasulov A. I. 
Published: July 2007

AbstractThe thermal conductivity of laminated GaSe monocrystals is studied in two crystallographic directions between 90 and 600 °K. The thermal conductivity is highly anisotropic; the value in the direction parallel to the layers exceeds that in the direction perpendicular to the layers by almost an order of magnitude. The mean free path of the acoustic phonons is calculated on the basis of the experimental lattice thermal conductivity, sound velocity and heat capacity data. The mean free path in the direction perpendicular to the layers (\documentclass{article}\pagestyle{empty}\begin{document}$ l\frac{1}{{{\rm ph}}} = 15.8 \times {\rm 10}^{{\rm - 8}} {\rm cm} $\end{document}) is found to be limited to the thickness of the Se—Ga—Ga—Se quadruple layers corresponding in this case to the lattice parameter (c = 15.883 Å). The mean free path in the direction parallel to the layers (l = 65 × 10−8 cm) exceeds the corresponding parameter (a = 3.734 Å) by an order of magnitude. Heat transfer by internal electromagnetic radiation is found in the high temperature region. A study is made of the effect of unilateral compression in the direction of the weak van der Waals bond (0001) both on the lattice and the photon components of the thermal conductivity of GaSe monocrystals.
On the new semiconducting compound HgTIS2
Authors: Guseinov G. D. , Ismailov M. Z. , Talybov A. G. 
Published: July 2007

AbstractA new three‐component coumpound corresponding to the stoichiometry of HgTiS2 is found. From the space group of 14/mmm a tetragonal elementary cell with the parameters a = (12.2 ± 0.05) Å and c = (6.6 ± 0.02) Å is established. Monocrystals of this compound are obtained and their electrical, photoelectric, optical, and other properties are studied. It is shown that this compound is a typical semiconductor having a gap width of about 1.3 eV.
The Temperature Dependence of Radioluminescence Yield in Alkali Halide Crystal Phosphors
Authors: Aluker E. D. , Mezina I. P. 
Published: July 2007

AbstractEmission spektra, thermal luminescence, and temperature dependence of luminescence yield of thallium and indium activated alkali halide phosphors are measured in the temperature range 80 to 600°K. The decrease of luminescence yield at low temperatures is explained as being due to localisation of electrons at activator centres.
On the Electric Conductivity of Semiconductors Caused by the Ionization of Thermal Lattice Defects
Authors: Vinetskii V. L. , Kholodar G. A. 
Published: July 2007

AbstractTheoretical calculations are made of the temperature dependences of the equilibrium carrier concentrations and intrinsic lattice defects in a semiconductor with self‐activated conductivity. Deviations from stoichiometry and electrical activity of both defect components as well as intrinsic conductivity are taken into account. The high‐temperature equilibrium conductivity of cuprous oxide crystals is found experimentally. Comparison between theory and experiment suggests that for cuprous oxide the conductivity is self‐activated for temperatures above 300°C. For crystals with a low concentration of excess oxygen N0, good agreement between the theory and experiment is obtained if it is assumed that only one component of the thermal defects is electrically active. The formation energy W of a nonionized intrinsic defect is found to be 2.6 eV, the ionization energy Ed of this defect being 0.64 eV, and the effective atomic concentration Neff in the lattice sites 1024 to 1025 cm−3. For crystals with a high concentration N0 the mechanism of self‐activated conductivity is more complex.
On the Theory of Lattice Oscillations of Dielectric Crystals in an External Electric Field
Authors: Ioffe I. V. 
Published: July 2007

AbstractA study is made of the change in the optical frequency of dielectric crystals due to an external electric field. The properties of the ferroelectric resonance in the presence of this field are also examined. It is shown that a new resonance of the spin and transverse acoustic waves can take place. The corrections to the frequencies of the coupled waves are found, and the parametric excitation of coupled waves is considered.
Field‐Emission Microscopy of Germanium
Authors: Ernst L. 
Published: July 2007

AbstractSamples of n‐type germanium with resistivity 5 ωcm which are cleaned by field desorption are examined using a field emission microscope. Some characteristics of the patterns obtained from the atomically clean surfaces are discussed. The adsorption of oxygen at pressures of 10−8 to 10−6 Torr is examined at room temperature. Adsorption occurs primarily on {001} planes and near {011} planes, whilst the actual {011} planes and the {111} plane seem to adsorb relatively less. The mean sticking probability is found to be about 0.1. The patterns show that oxide clusters also develop in the course of adsorption. Hence only a possible minimum value of the increase in the work function may be calculated from the change of slope of the Fowler‐Nordheim characteristic.
Studies of the Electrical Properties of Uranium Oxides III. Thermoelectric Power of α‐U3O8
Authors: George A. M. , Karkhanavala M. D. 
Published: July 2007

AbstractThe thermoelectric power of nuclear pure α‐U3O8 is measured in air over the temperature range 100 to 850°C. The results show that the oxide is an n‐type semiconductor. The plots of thermoelectric power versus the reciprocal of the absolute temperature consist of two regions: (i) above 480°C with a slope of 0.4 V and (ii) below 480°C where the thermoelectric power shows considerable variations; the average slope being of the order of 0.01 V. The results are analysed on the basis of the Wagnermodel for the defect structure of α‐U3O8. The slope of 0.40 V is related to the formation energy of the charge carriers which is calculated to be 1.065 eV. The low temperature part of the plot probably shows the temperature dependence of the thermoelectric power due to frozen‐in donor concentrations.
Diffusion from a Thin Film into a Dissociating or Evaporating Solid
Authors: Ghoshtagore R. N. 
Published: July 2007

AbstractAn analytical solution is obtained for concentration gradient in solid‐state diffusion where the solid is evaporating or dissociating at an appreciable rate. Some numerical methods are also indicated and the results discussed in special context to the tracer techniques of determining diffusion coefficients.
The Electrical and Thermal Resistivities of Iron
Authors: Chari M. S. R. 
Published: July 2007

AbstractAccording to Weiss and Marotta, the electrical resistivity of iron may be split into three components ϱr, ϱg and ϱs being respectively the residual resistivity, the ideal (lattice scattering) term and the spin‐disorder scattering term. Bäcklund has similarly attempted to separate out the corresponding components of the electronic thermal resistivity, based on a modified Wiedemann‐Franz‐Lorenz law. In this work the lattice‐scattering term is obtained using the normal value (Ln) of the Lorenz number, while ϱg includes an electrical resistivity term attributed to zero point vibrations. In the present treatment values are calculated for weg and the lattice thermal conductivity by taking for the electronic Lorenz number the value given by Makinson for a typical monovalent metal having a Debye temperature equal to that of iron. These values agree with those obtained by Bäcklund.
Temperature Dependence of the Critical Field in Superconducting Vanadium
Authors: van Gurp G. J. 
Published: July 2007

AbstractThe critical field Hc2 of superconducting vanadium is determined from critical current measurements on cold‐rolled and annealed foils and on a single crystal. The temperature dependence is found to be stronger than predicted by theory. The critical field is found to be anisotropic in the single crystal. Values of χ1 = Hc2/Hc χ2 are determined which, by ecxtrapolation to zero resistivity, show that pure vanadium is a type II superconductor with χ1 comparable to that for pure niobium.
Untersuchungen der Bereichstruktur von Nickeleinkristallen II. Messungen und Beobachtungen an prismatischen Kristallen mit 〈110〉 als Achse
Authors: Schwink Ch. , Grüter O. 
Published: July 2007

AbstractUnsere Beobachtungen und Messungen an zweizähligen Nickelkristallen erstrecken sich auf den gesamten Feldbereich, in dem periodische Bitterstreifen auftreten Unterschiede zwischen schlanken und gedrungenen Kristallen werden darauf zurückgeführt, daß bei letzteren das Feld über den Probenquerschnitt nicht homogen ist. Das entmagnetisierende Feld der Kristalle nimmt zunächst linear mit der Magnetisierung bis zu einem Maximalwert zu, darüber fällt es aber wieder auf einen Sättigungswert asymptotisch ab. Die Hauptlinien der Bittermuster auf den Seitenflächen der Kristalle trennen stets zwei Bereiche mit konvexem Winkel zwischen den Magnetisierungsrichtungen. Die Kurve der Periodenbreite mit dem Feld zeigt für schlanke Kristalle einen charakteristischen, stufenartigen Verlauf; er läßt sich mit der Entwicklung der Bittermuster auf den Seitenflächen der Kristalle korrelieren. Das Auftreten periodischer Bitterstreifen bis zu Feldern über 115 Oe läßt sich durch Berücksichtigung von K2 verstehen.
Die kritische Schubspannug kubischer Kristalle mit Fehlstellen tetragonaler Symmetrie IV. Die untere Streckgrenze von α‐Eisen
Authors: Frank W. 
Published: July 2007

AbstractAn Hand von Beispielen wird gezeigt, daß bei α‐Eisen üblichen Kohlenstoffgehaltes unterhalb Raumtemperatur die Temperaturabhängigkeit der unteren Streckgrenze τ0 quantitativ durch kurzreichende elastische Wechselwirkungskräfte erklärt werden kann, welche der in der Nähe der Gleitebenen befindliche Kohlenstoff auf die Versetzungen ausübt. Bei mehr als 0,1 At% C liegt der wirksame Anteil in Form kleiner Ausscheidungen, bei niedrigeren C‐Gehalten interstitiell gelöst vor. Bei hohen Gehalten an gelöstem Kohlenstoff trägt dieser außerdem über den induzierten Snoek‐Effekt zu τ0 bei. Bei den bisher untersuchten C‐armen Proben wird τ0 durch den Sauerstoffgehalt bestimmt.
Elektronenmikroskopie kleiner Fehlstellenagglomerate in bestrahlten Metallen II. Untersuchungen an neutronen‐ und ionenbestrahltem Kupfer sowie neutronenbestrahltem Nickel
Authors: Rühle M. 
Published: July 2007

AbstractDie nach Neutronen‐ und Ionenbestrahlung in Kupfer sowie die nach Neutronenbestrahlung in Nickel im Elektronenmikroskop beobachtbaren Defekte werden untersucht. Durch quantitativen Vergleich der aus der Theorie des Kontrastes folgenden Kontrastbreite mit den beobachteten Defektgrößen läßt sich die wahre Größe und Größenverteilung der Agglomerate ermitteln. Die Analyse des Defekttyps ergab (siehe [1]), daß sowohl nach Neutronen‐ als auch nach Ionenbestrahlung (im Mikroskop mit 100 kV‐ bzw. 40 kV‐Ionen) nahezu alle beobachtbaren Defekte in Kupfer durch Kondensation von Leerstellen entstanden waren. Dasselbe ergab sich auch für die beobachtbaren Defekte in neutronenbestrahltem Nickel. Die bei der Bestrahlung auch gebildeten Zwischengitteratome müssen deshalb entweder an Senken (Korngrenzen, Versetzungen, Einzelleerstellen) ausgeheilt oder zu noch nicht im Elektronenmikroskop auflösbaren Defekten agglomeriert sein. Durch einen quantitativen Vergleich der beobachteten Defektdichte mit dem Verlauf der Energieverteilungskurve der primären Rückstoßatome folgt, daß alle primären Rückstoßatome, deren Energie größer als (30 ± 10) keV ist, einen im Elektronenmikroskop sichtbaren Defekt erzeugen.
Nuclear Magnetic Resonance in Liquid Gallium Alloys
Authors: van Der Lugt W. , van Der Molen S. B. 
Published: July 2007

AbstractThe Knight shifts of the Ga, In, and Sn nuclear magnetic resonance in liquid Ga‐In, Ga‐Sn, and Ga‐Zn alloys are determined as a function of the concentration. The measurements cover the entire range of concentration for the Ga‐In and Ga‐Sn alloys and concentrations up to 40 at% Zn for the Ga‐Zn alloys. The most important result is the insensitivity of the Knight shift to concentration variations in each of the three alloy systems. The results are discussed in terms of two simple models; these models fail to give a qualitative explanation of the experimental data.
A New Approach to the Vibronic Spectra of Molecular Crystals
Authors: Broude V. L. , Rashba E. I. , Sheka E. F. 
Published: July 2007

AbstractA study is made of the experimental consequences of the theory of the vibrational spectra of molecular crystals presented recently in [3]. A discussion is also given of the model used in this theory. A detailed comparison is made between the theory and experimental results for pure and isotropic doped naphthalene crystals in the M‐band region. The theory accounts for the decay of electronic‐vibrational intra‐molecular excitations into pure electronic and intra‐molecular vibrational excitations by a resonance interaction. In this case the crystal spectrum should exhibit a wide absorption band corresponding to two‐particle excitation. If the reduction of the vibrational frequencies of the molecule accompanying its electronic excitation is comparable with the pure electronic excitation band width, the spectrum should also show a narrow band corresponding to a one‐particle excitation. These bands should be associated with the vibrational band which is observed experimentally. This idea is used to analysis the absorption in the first vibrational transition region of a naphthalene crystal. The one‐ and two‐particle excitation regions are identified and a quantitative analysis of the data is made which is in accordance with the theory. Collective effects, connected with the excitation decay, appear to be important in this transition region. In this connection of particular interest is an analysis of peculiarities of impurity vibrational absorption in isotopic solutions. Comparison between the spectral data naphtalene deutero‐isotopes and the theory also indicates the importance of some complicated collective interactions.
On the Kinetics of the Crystal Phosphor Luminescence
Authors: Antonov‐Romanovskii V. V. 
Published: July 2007

AbstractOn the basis of the diffusion equation for the motion of free charges, a monomolecular recombination probability is calculated for electron‐hole pairs. The calculation includes short‐time luminescence arising from recombination prior to the localization of the electronhole pair and extended luminescence due to recombination after localization. A qualitative discussion is given of the case in which a particular photon creates more than one electronhole pair.
On the Mixed Mechanism of Electron Scattering in InSb Crystals
Authors: Filipchenko A. S. , Nasledov D. N. 
Published: July 2007

AbstractExperimental data for indium antimonide on the Hall‐mobility of electrons and the thermal e.m.f. in a weak magnetic field are compared with theory taking into account the non‐parabolicity of the conduction band. Formulae are deduced for the thermal e.m.f. and electron mobility for the case of a mixture of electron‐scattering mechanisms. It is then shown from the experimental data that, in doped indium antimonide crystals, mixed scattering does occur which involves impurity ions, and optical and acoustic phonons.
Effect of Different Lattice Defects on the Mobility of Dislocations in Alkali Halide Crystals
Authors: Boyarskaya Yu. S. , Zhitaru R. P. , Koloskova V. G. 
Published: July 2007

AbstractSingle crystals of KCl and NaCl are subjected to additive colouration treatment and X‐irradiation, and their hardening and softening observed. It is found that F‐centres and colloids have no appreciable effect on the mobility of dislocations. The assumption is made that certain defects are responsible for the hardening of irradiated NaCl crystals. These defects are due to soft irradiation and it is possible that they may be concerned with the generation of new vacancies during the irradiation.
Local Mode Absorption by U‐Centres in Alkali‐Halide Mixed Crystals
Authors: Barth W. , Fritz B. 
Published: July 2007

AbstractThe local mode absorption bands of U‐centres are affected by the presence of alkali or halogen foreign ions in the host lattice in the following ways: (a) new bands appear, which are displaced to higher and lower frequencies (b) the entire spectrum undergoes a concentration‐dependent shift and broadening. These effects are studied for U‐centres in KCl:Rb+, KCl:Na+, KCl:Br−, RbCl:K+,KBr:Rb+ and RbBr:K+ with doping concentrations between 10−3 and 10−1. Groups of new lines can be attributed to U‐centres having doping ions in the next three shells of neighbouring ions. The intensities of these lines are slightly greater than expected from the statistical probabilities for such configurations. The splitting observed in a characteristic pair of lines compares favourably with a simple calculation for the case of a U‐centre perturbed by a foreign cation in a nearest neigbour (100) position. The relation between the lattice constant and local mode frequency obtained in mixed crystals may be used to discuss lattice relaxation near U‐centres and “quasiharmonic” temperature‐dependent band shifts.
On the Kinetics of Plastic Deformation of Some Alkali Halide Crystals
Authors: Komnik S. N. , Bengus V. Z. , Lyak E. D. 
Published: July 2007

AbstractA study is made of the kinetics of plastic deformation in LiF, NaCl, KCl, and KBr crystals. This includes the non‐uniformity of the plastic deformation, the strain rate dependence of this non‐uniformity, the strain rate dependence of the flow stress, and the dislocation structure of the deformed crystals. In the above crystals a regular change of the kinetics is found for a decrease of the elastic anisotropy factor A = 2 C44/(C11 – C12). The correlation of the macroscopic behavior of the crystals with their elastic anisotropy is assumed if other conditions are similar.