bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vapour‐Pressure Investigations of Impurity Diffusion and Solubility in AII–BVI Compounds Demonstrated for the System CdS:Au:S2
Authors: Nebauer E. 
Published: July 2007

AbstractIt is shown that for investigations of disorder problems in AII–BVI compounds it is relevant to measure the diffusion coefficient D and the solubility S as functions of the vapour pressure p of the components. Using the tracer technique this method is exemplified in detail for a cation impurity diffusion process in the system CdS:Au:S2. The measured concentration profiles C(x) are not of Fick's type. After eliminating surface and dislocation diffusion (Fisher analysis), D(T, p, C) and also simultaneously S(T, p) can be obtained. The results are explained in a disorder model with controlled intrinsic disorder. It is found that gold diffuses in CdS via singly‐charged cadmium vacancies and acts as a singly‐charged acceptor.
A Neutron Diffraction Study on Gallium‐Substituted Magnetite
Authors: Gamari‐Seale H. , Papamantellos P. 
Published: July 2007

AbstractThe distribution of Ga3+ and Fe3+ ions in tetrahedral and octahedral sites, A and B, of the inverted spinel Fe3−tGatO4, with t = 0.442 and 0.628 is determined from neutron diffraction measurements on two synthetic single crystals. To avoid a great extinction effect the crystals are cut into small cylindrical fragments. The extinction correction coefficients are found by a graphical method using the extinction formula Ic = Io (A + B Ic). Because of the similarity of the nuclear scattering length of Ga3+ and Fe3+ the distribution of the ions is found only from the magnetic reflections. By applying a magnetic field in the direction of the scattering vector, it is possible to separate the magnetic from the nuclear scattering. The Ga3+ ions are found to be distributed between the two sites as follows: 93 and 76% in the tetrahedral, 7 and 24% in the octahedral site for the two crystals, respectively. A least square refinement of the corrected nuclear data yields agreement factors R = 0.03 and 0.04; the resulting oxygen parameters u = 0.369 ∓ 0.0006 and 0.369 ∓ ∓ 0.0008, respectively, indicate the usual shift for the inverted spinel from the ideal value 3/8.
Solution‐Hardening and Deformation of Niobium‐Tungsten Alloys
Authors: Harris B. 
Published: July 2007

AbstractThe results of some experiments on the strain‐rate and temperature dependence of the flow stress of some dilute niobium‐tungsten alloys are reported. Alloys containing 0.25, 0.5, and 2.6 at% tungsten exhibit unusual twin peaks in the strain‐rate sensitivity as a function of temperature, and this leads to abnormally high values of the activation energy of deformation in the region of 150 °K. And yet the behaviour of a 5.3 at% W alloy appears to be indentical with that normally observed for b.c.c. metals. The results suggest that two deformation mechanisms are overlapping below 150 °K, and current theories of solute hardening and deformation of b.c.c. metals are examined to provide an explanation.
Die kritische Schubspannung mit zweiwertigen Kationen dotierter Alkalihalogenide I. Nicht‐agglomerierte Fremdion‐Leerstellen‐Paare
Authors: Frank W. 
Published: July 2007

AbstractEs wird gezeigt, daß bei Alkalihalogeniden, welche zweiwertige Kationen in Form von Fremdion‐Kationleerstellen‐Paaren (elastischen Dipolen) enthalten, die kritische Schubspannung τ0 durch die elastische Wechselwirkung dieser Dipole mit den Versetzungen verursacht wird. Unterhalb Raumtemperatur ist τ0 durch das thermisch aktivierte Vorbeigleiten von Versetzungen an Dipolen in der Nähe der Gleitebenen bestimmt, während oberhalb Raumtemperatur der induzierte Snoek‐Effekt der Dipole im Spannungsfeld der Versetzungen τ0 entscheidend beeinflußt. An einen temperaturunabhängigen Bereich oberhalb Raumtemperatur schließt sich ein Hochtemperaturabfall von τ0 an, zu dem neben dem induzierten Snoek‐Effekt der Zerfall der Dipole in zweiwertige Kationen und Kation‐Leerstellen beiträgt.
Nonlinear Magnetooptical Phenomena in Semiconductors (I)
Authors: Kołodziejczak J. 
Published: July 2007

AbstractA theory of a nonlinear magnetooptical phenomena associated with free carriers in semiconductors is proposed. Starting from a nonlinear Boltzmann equation, the effects of optical mixing and higher harmonics generation are predicted. The calculations are carried out assuming nonparabolic energy band of ellipsoidal symmetry. Thus the results can be applied to a wide class of semiconductors as for example to all those with one energy minimum as well as to many‐valley semiconductors.
Observations de sources et de réactions entre dislocations partielles de macle sur des topographies aux rayons X
Authors: Sauvage M. 
Published: July 2007

AbstractL'observation directe de dislocations partielles de macle sur des topographies aux rayons X montre que les sources sont des centres de concentration de contraintes. Le mécanisme de nucléation et croissance des macles est donc le mécanisme de „nucléation hétérogène”︁. Les interactions entre dislocations glissiles et défauts du réseau donnent naissance à des configurations particulières dont on essaie de rendre compte théoriquement.
Phonon‐Induced Hyperfine Coupling of V2+ Ion in Cubic Crystalline Fields
Authors: Shrivastava K. N. 
Published: July 2007

AbstractThe effect of dynamic phonon interaction on the hyperfine fields of ions with electronic configuration 3d3 has been examined theoretically. The zero‐point vibrational contribution and the temperature dependent part is discussed for both the acoustical and the optical phonons in a covalent model. As the amplitude of phonon vibrations is thermally increased a net decrease in the V2+ hyperfine interaction in octahedrally coordinated environment is predicted the temperature dependence of which is in agreement with experimental measurements in V2+ doped MgO.
Scattering Effects with Channeled Ions
Authors: von Jan R. 
Published: July 2007

AbstractThe angular distribution F(α) is calculated for fast ions that have traversed a lattice channel with an axis in the direction α = 0. For both axial and planar transmission channeling, intensity maxima are expected at \documentclass{article}\pagestyle{empty}\begin{document}$ |\alpha _{\max} | = \alpha _0 \sqrt {(1 - \eta ^t)/(1 - \eta ^l)} $\end{document}, where α0 is the angle of incidence, and ηt and ηl denote the relative energy loss of transverse and longitudinal motion. The scattering effects provide a direct method to measure separately longitudinal and transverse stopping powers for channeled ions.
Low‐Temperature Neutron Radiation Damage and Recovery in Beryllium
Authors: Delaplace J. , Nicoud J. C. , Schumacher D. , Vogl G. 
Published: July 2007

AbstractIn beryllium neutron irradiated at 4.2 °K, the defect production and subsequent recovery up to 350 °K have been studied by means of electrical resistivity measurements. The data are discussed in view of our present knowledge on point defect phenomena in other metals, in particular aluminium, which exhibits after neutron irradiation a similar recovery behaviour as beryllium.
Noise in Thin Films Metal‐Oxide‐Metal AlAl2O3Al
Authors: Lecoy G. , Gouskov L. 
Published: July 2007

AbstractIt is the purpose of this note to verify the existence of tunneling through the oxide layer of metal‐oxide‐metal structures. Noise measurements on thin AlAl2O3Al sandwiches (30 Å thick) yield full shot noise at high frequencies (v > 1000 Hz) and v−3/2 noise for v < 1000 Hz. From conductivity and noise measurements the dependence of each individual tunnel current on voltage and temperature is determined. Experimental values of I1/I2 are in good agreement with the Boltzmann law owing to the tunneling process.
Dislocation Theory of Susceptibility and Coercive Force of Silicon Iron
Authors: Mishin D. D. 
Published: July 2007

AbstractIn the present work the dislocation theory of the susceptibility and coercive force of silicon iron is developed. Calculations are made of the force between a Bloch wall of the {100}‐180° type and dislocations really existing in this material. The susceptibility and coercive force of silicon iron are calculated, and conditions are stated under which the temperature dependence of susceptibility and coercive force of this material changes markedly.
On the Problem of Depth Distributions in Oxides Following High‐Dose Labelings. (Sputtering and Depth‐Distribution Phenomena, Part III)
Authors: Kelly R. 
Published: July 2007

AbstractIt has been shown previously that meaningful depth‐distribution parameters can be obtained with Al, KCl, and Pt, following high‐dose labelings at ≦ 10 keV, by sputtering the targets with 2 or 3 keV ions. We present here similar data for the oxides Al2O3, MgO, NiO, SiO2, TiO2, and UO2 labeled to a high dose at 4 keV. It is found that, when the sputtering energy is 2 keV, the implied ion ranges are roughly a factor of 2 less than might be expected (shown with all oxides), while, when the sputtering energy is 8 keV, the implied ranges are smaller still (Al2O3, TiO2). Moreover, shortened ranges are also found by sputtering oxide skins (Al, Mg, Ti), by sputtering bulk materials at about −150°C (Al2O3, MgO, UO2), by applying an anodizing‐stripping technique (Al2O3), and by comparing high‐dose sticking factors (all oxides). It is concluded that the available evidence is compatible with two extreme views. Possibly the shortened ranges found with high‐dose labeled oxides are in error, for example due to bombardment‐enhanced gas motion when the sputtering technique is used, or due to excess oxide growth when anodizing‐stripping is used; alternatively they may be real, as would be true if an effect such as bombardment‐enhanced gas motion occurred during the labeling.
Self‐Diffusion in α‐Silver‐Cadmium
Authors: Gardner A. B. , Sanders R. L. , Slifkin L. M. 
Published: July 2007

AbstractThe diffusion of tracers of silver and cadmium has been measured in AgCd alloys over the range 31 to 37 at% Cd, thus extending the data of Schoen to compositions near to the phase boundary, and facilitating a comparison with Zener relaxation studies by Turner, Dozier, and Williams (see preceding paper). The present diffusion results fit smoothly onto an extrapolation of Schoen's data, but the decrease in activation energies with increasing cadmium content appears to flatten out at the higher concentrations. It is suggested that a temperature dependence of the short range order may contribute to the activation energies.
Temperature Dependent Spin‐Lattice Relaxation Times for Conduction Electrons in Lithium Particles in n‐Irradiated Lithium Fluoride
Authors: Watts A. J. , Cousins J. E. 
Published: July 2007

AbstractMeasurements of the conduction electron spin resonance linewidths of Li particles in neutron‐irradiated LiF are presented as a function of temperature and at a frequency of 9.27 GHz. A temperature range of 20 to 500°K was covered, and a genuine reversible temperature dependence of the linewidths was observed. The results are interpreted in terms of a temperature dependent surface relaxation mechanism and a temperature dependent intrinsic one. The latter has a room temperature value of 45 mG which compares favourably with the theoretical prediction of Overhauser. It is shown that the assumptions made for the analysis are compatible with the results of other workers.
Experimental Observations of the Absorption, Infra‐Red Emission, and Excitation Spectra of Cr3+ Ions in ZnWO4
Authors: Reynolds M. L. , Hagston W. E. , Garlick G. F. J. 
Published: July 2007

AbstractOptical absorption, infra‐red emission, and excitation spectra have been measured for trivalent chromium ions in the zinc tungstate lattice. In contrast to the case of ruby the lowest excited state is 4T2(F) and emission results from the 4T2−4A2 transition. The emission at about 1 μm is of broad band type with a decay time of about 10−5 s and involves a significant Stokes shift. These characteristics are consistent with the strong dependence of the energy of the 4T2 state on the crystal field parameter, and a large activator‐lattice interaction. Rhombic symmetry is indicated for the Cr3+ ion site, but tetragonal distortion occurs for the excited states.
Low Temperature Neutron Radiation Damage and Recovery in Magnesium
Authors: Delaplace J. , Hillairet J. , Nicoud J. C. , Schumacher D. , Vogl G. 
Published: July 2007

AbstractIn magnesium neutron‐irradiated at 4.2°K the defect production and the subsequent recovery up to 350°K were studied by means of electrical resistivity measurements. Additional experimental evidence is presented from preliminary stored energy, internal friction, and electron microscope studies on neutron‐irradiated magnesium, and from electrical resistivity measurements on electron‐irradiated magnesium. The principal recovery peak occurs between 90 and 160°K.
A Stochastic Model of Creep
Authors: Feltham P. 
Published: July 2007

AbstractA model of creep in solids is developed in which flow units, identified with dislocation segments in crystals, overcome energy barriers u1 ≦ u ≦ u2 with the aid of thermal activation. Each successful transition of a unit increases or decreases the barrier for the subsequent jump by a stress‐dependent increment. The continuity equation of the Markov process defined by the premise yields activation energy distributions as particular solutions. The distributions are used to derive relations for logarithmic, power‐law, and quasi‐viscous creep. The model delineates the scope of temperature cycling in the determination of activation energies.
Empirical Relationships for the Emission Energies and Lifetimes of the F‐Center
Authors: Gilbert R. L. 
Published: July 2007

AbstractEmpirical relations for the emission energies ϵ of the F‐center in the Na, K, Rb, and Cs halides, and for the lifetimes τ have been established with the following forms:

and

where Ko is the optical dielectric constant. Two different relations appear to exist for τ. One follows from measurements of τ at liquid helium temperature, the other follows from τ extrapolated from measurements above liquid nitrogen temperature with the Swank‐Brown curve. The implications of the existence of these curves are discussed.
Electron Diffraction Contrast from Three Parallel Overlapping Stacking Faults
Authors: Humble P. 
Published: July 2007

AbstractThe electron diffraction contrast to be expected from three parallel overlapping intrinsic stacking faults has been computed. It is shown that faint fringe contrast always arises from this configuration, even in the limiting case when the faults lie on neighbouring slip planes. This is contrary to previous predictions. Moreover, by comparison with experimental images, it is shown that the faint fringe contrast is generally detectable and that the actual spacing of the three faulted planes may be deduced. The effect of dislocation strain‐fields on this faint contrast is discussed and some results for the contrast from two parallel intrinsic stacking faults are presented.
Crystal Field Calculation of Principal Magnetic Susceptibilities and Anisotropy Variation with Temperature of Anhydrous Neodymium Chloride
Authors: Taneja S. P. , Puri S. P. 
Published: July 2007

AbstractIn the temperature range 5 to 300°K, the principal susceptibilities of single crystals of anhydrous NdCl3 have been calculated on the assumption that a single suitable trigonal field of C3h symmetry exists in the neighbourhood of the Nd3+ ion. Furthermore the variation of magnetic anisotropy with temperature is studied and found to increase with the decrease of temperature. The g‐values for the lowest level, viz., g∥ = 4.103, g⟂ = 1.746, compare well with the experimental values obtained from paramagnetic resonance absorption. The following crystal field parameters, reported by Judd, were used in these calculations: A〈r2〉 = 103.7 cm−1, A〈r6〉 = −44.51 cm−1, A〈r4〉 = −36.01 cm−1, A66〈r6〉 = 426.21 cm−1.
Some Transport Coefficients in Cadmium Sulphide
Authors: Sodha M. , Sharma S. 
Published: July 2007

AbstractAn investigation is made of the dependence of Hall coefficient, Hall mobility, and coefficient of magnetoresistance in CdS on electric field, magnetic field, and scattering mechanisms. The scattering of carriers by acoustic mode of lattice scattering as well as piezoelectric potential is considered.
Polarization of Optical Absorption and Emission Bands due to Donor‐Acceptor Associates in Wurtzite Type Crystals
Authors: Boyn R. 
Published: July 2007

AbstractA discussion is given of the possibilities of orientation of donor‐acceptor associates in wurtzite type crystals and the polarization of absorption and emission bands due to electric dipole transitions in such associates. It is found that bands of this kind tend to be polarized more strongly if the corresponding associate contains interstitials than if two defects on lattice sites are involved.
Photoconduction in CdS Crystals Generated by a Modulated Electron Beam
Authors: Stössel W. , Zimmermann W. 
Published: July 2007

AbstractA modulated photocurrent in CdS crystals is obtained by irradiation with an intensity modulated electron beam. The experimental set‐up for the irradiation is described. From the frequency dependence of the ac photocurrent a relaxation time τR is defined. τR decreases with increasing irradiation intensity B. At complete filling of the traps it reaches the value of the free electron lifetime τ. From the dependence τR(B) the approximate depth and the concentration of the traps, which are involved in the relaxation processes, are determined to Ec − EH = 0.215 eV and H = 8.5 × 1014 cm−3.
On the Trapping of Free and Release of Localized Carriers in Solids
Authors: Antonov‐Romanovskii V. V. 
Published: July 2007

AbstractThe effective cross‐section of trapping, σeff, and the “frequency” factor ωeff measured in experiments in the case of attractively charged localization centres may strongly differ from the real gaskinetical σk and ω, but for the ratio yields ωeff/σeff = ω/σk. The greater the difference the less is the carriers mean free path l. In this sense, for example, the alkali halides are of great interest. The free carriers distribution function with respect to the localization centres \documentclass{article}\pagestyle{empty}\begin{document}$ \overleftarrow {\eta (r)} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \overrightarrow {\eta (r)} $\end{document} in the cases of trapping and release processes, respectively, complete each other to the thermal equilibrium function ηT(r).
Reflectivity Spectra of the Rhombohedral Crystals Bi2Te3, Bi2Se3, and Sb2Te3 over the Range from 0.7 to 12.5 eV
Authors: Sobolev V. V. , Shutov S. D. , Popov Yu. V. , Shestatskii S. N. 
Published: July 2007

AbstractThe reflectivity spectra (polarisation E ⟂ c) of the homologous group of rhombohedral crystals Bi2Te3, Bi2Se3, and Sb2Te3 have been investigated in the range 0.7 to 12.5 eV. The complex structure of the two reflectivity main maxima, lying in the range 1 to 5 and 6 to 11 eV, respectively, and its similarity in all three crystals have been established. The energy variation of the reflectivity peaks in dependence of the atomic composition shows the anomalous decrease of the interband gaps in Sb2Te3 respective to Bi2Te3. The results obtained are discussed in terms of published bismuth telluride band structure.
The Active Slip Volume and the Temperature‐Dependent Processes in Stage I of Single Crystals of Cu Alloys
Authors: Schwink Ch. , Traub H. 
Published: July 2007

AbstractInvestigations of the easy glide region in single crystals of well‐known f.c.c. Cu alloys between 85 and 400°K are reported. From careful measurements of the strain rate dependence of the flow stress and from microscopic observations (static and cinematographic) of the development of the glide bands it is concluded that the “active slip volume” [1] of these crystals depends on strain rate and temperature. A detailed analysis of the results yields values for the number, the activation energy, and the activation volume of the obstacles responsible for the thermally activated process. We suggest that the obstacles are statistically distributed clusters of the atoms alloyed to copper.
Magnetization and Magnetostriction of Hexagonal Cobalt Single Crystals with Internal Stresses
Authors: Köster E. 
Published: July 2007

AbstractMeasurements of magnetization and magnetostrictive changes of the length were carried out on a plastically deformed cobalt single crystal at low magnetic fields. The results are in good agreement with theoretical calculations by Kronmüller et al. [1]. From this it is concluded that the magnetization processes within the closure structure of ferromagnetic domains at the crystal surface have no noticeable influence on the magnetization compared with the processes in the crystal volume.
Theory of Light Emission by Impurity Centres from Non‐Equilibrium Vibrational States
Authors: Peuker K. , Trifonov E. D. 
Published: July 2007

AbstractA theoretical study is made of light emission from impurity centres of crystals in the non‐equilibrium vibrational state, which appears as a result of the excitation of one of the vibrational sublevels belonging to the excited electronic term. It is shown that owing to these processes anti‐Stokes luminescence may be observed at T = 0°K. The validity of the kinetic equation approach is proved.
The Theory of the Absorption and Infrared Emission of Cr3+ Ions in ZnWO4
Authors: Reynolds M. L. , Hagston W. E. , Garlick G. F. J. 
Published: July 2007

AbstractThe effect of fields of lower symmetry (in the crystal field approximation) on the energy levels of trivalent chromium ions in the zinc tungstate lattice is discussed. Calculations show that the optical spectra previously reported [1] can be interpreted in terms of a field of rhombic symmetry acting on the Cr3+ ion provided we include the effects of tetragonal distortion in the excited states.
Modulation of Near Infrared Radiation by Acoustoelectric Domains in n‐Type GaAs at Room Temperature
Authors: Boccon‐Gibod D. 
Published: July 2007

AbstractOptical experiments have enabled measurements of the absorption coefficient of n‐type GaAs to be made at room temperature near the absorption edge by an acoustoelectric domain located at the anode. Moreover, the shape of the domain can be deduced and in addition the acoustic flux is shown to be an important factor in the variations of the absorption coefficient. Some results are also given of local resistivity variations in n‐type GaAs by the injection of free carriers when a GaAs laser beam is focused on the sample.
Zur statistischen Theorie der Diffusionsprozesse in kondensierten Systemen
Authors: Kowalenko N. P. , Ebeling W. 
Published: July 2007

AbstractAuf der Grundlage der klassischen statistischen Mechanik und der Methode der Projektionsoperatoren von Zwanzig wird eine Diffusionsgleichung hergeleitet, die den Einfluß räumlicher und zeitlicher Dispersion berücksichtigt. Im Falle einer geringen räumlichen Inhomogenität unterscheidet sich diese Gleichung von der gewöhnlichen Diffusionsgleichung durch ihren nicht‐Markoffschen Charakter. Im Grenzfall t → ∞ wird die gewöhnliche Diffusionsgleichung erhalten. Es wird eine Methode sukzessiver Approximationen entwikkelt, die höhere räumliche Ableitungen einschließt. Auf der Grundlage der allgemeinen, nicht‐Markoffschen Gleichung wird gezeigt, daß ein Übergang von reversibler Wanderung für kleine Zeiten zu irreversibler Wanderung für große Zeiten existiert. Es wird die Lösung der nicht‐Markoffschen Gleichung für das spezielle Modell der Brownschen Bewegung untersucht.