bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elektronenmikroskopie kleiner Fehlstellenagglomerate in bestrahlten Metallen I. Theorie des Kontrastes und experimentelle Methoden zur Ermittlung des Defekttyps
Authors: Rühle M. 
Published: July 2007

AbstractDurch Teilchenbestrahlung entstehen in Metallen elektronenmikroskopisch beobachtbare Fehlstellenagglomerate. Die Struktur der Fehlstellenagglomerate ist dann jedoch nicht mehr unmittelbar aus dem Kontrastbild zu entnehmen, wenn die Defekte kleiner als ca. 150 Å sind. Jedoch läßt sich durch Vergleich von gezielten Experimenten (dynamische Zweistrahl‐Abbildung) mit den Ergebnissen der Theorie des Kontrastes der Typ dieser kleinen Defekte (d. h. mögliche einfachste Form der Defekte und Unterscheidung zwischen Leerstellen‐ und Zwischengitteratomagglomeraten) ermitteln. Diese Analyse wurde an den in neutronenbestrahltem Kupfer beobachtbaren Defekten durchgeführt. Dabei zeigte sich, daß nahezu alle ausgewerteten Defekte am einfachsten durch Franksche Versetzungsringe vom Leerstellentyp zu erklären sind.
Scattering of Phonons at Defect Planes in the Simple Cubic Lattice
Authors: Ludwig W. , Pick H. 
Published: July 2007

AbstractA discussion is given of the scattering of phonons in cubic crystals at (001)‐ and (011)‐defect planes (planes with impurity atoms, free surfaces and boundaries between two media) using a simple model. Reflection and transmission coefficients are calculated as functions of the wavevector and polarization of the incoming wave. The different forms of the scattering states are discussed.
Transmission Electron Microscopic Observation of Lattice Deformation in Antiphase Boundaries of Ordered Fe‐Si Alloys
Authors: Gemperle A. , Kočík J. 
Published: July 2007

AbstractTransmission electron microscope studies of ordered Fe‐Si alloys show that a fringe contrast associated with antiphase boundaries appears in fundamental reflections. This effect is explained as being due to a deformation of the lattice by the boundary. The usual method employed in contrast experiments is used to find the direction of the additional displacement vector at the boundaries.
The Effect of Cadmium Additions on the Fracture Strength of Sodium Chloride Single Crystals
Authors: Harrison R. P. 
Published: July 2007

AbstractThe fracture characteristics of sodium chloride single crystals containing cadmium additions have been determined as a function of heat treatment and testing temperature. Precipitate particles reduce the fracture stress and strain at testing temperatures below −50°C. The results are related to other recent investigations into the mechanics of cleavage fracture in brittle solids.
Nuclear Magnetic Resonance and Mössbauer Effect Study of Sn119 in Rare Earth‐Tin Intermetallic Compounds
Authors: Borsa F. , Barnes R. G. , Reese R. A. 
Published: July 2007

AbstractThe nuclear magnetic resonance and Mössbauer effect of Sn119 have been studied in the cubic intermetallic compounds RSn3 (R = La, Ce, Pr, Nd, Sm, and Yb). Both the isotropic and anisotropic components of the Knight shift were determined in the temperature range 77 to 400°K. In the cases of PrSn3 and NdSn3 in which the shift measurements are proportional to the magnetic susceptibility, the results may be understood in terms of the Ruderman‐Kittel‐Kasuya‐Yosida theory, with an exchange interaction, T = −0.2 eV. The cases of CeSn3 and SmSn3 do not appear to be interpretable in terms of the RKKY theory. For PrSn3, NdSn3, and SmSn3 the Mössbauer effect of the Sn119 yielded a resolved quadrupole splitting of approximately 1.1 mm/s, independent of temperature in the range 4.2 to 300°K. The isomer shift was +0.70 mm/s, relative to Mg2Sn, also independent of temperature. The measured quadrupole coupling has been compared with that expected on the basis of the ionic model. No magnetic splitting was ever unambiguously observed, even at 1.5°K. Assuming that the magnetic splitting remains masked by the quadrupole interaction leads to an estimate of Heff ≦ 9 × 103 Oe in PrSn3 and NdSn3.
Disorder Resistivity and Spin Depolarization in Rare‐Earth Alloys
Authors: van De Braak H. P. , Caspers W. J. 
Published: July 2007

AbstractComparison of experimental results with the theory of the electrical resistivity of ferromagnetic rare earth alloys suggests a rapid redistribution of the scattered conduction electrons over the two spin orientations. In order to investigate whether this effect might be due to the Coulomb interaction between the conduction electrons, the mean free path for depolarization is calculated. In the Born approximation, the mean free path is of the order of some centimeters, whereas the mean free path for scattering is about 50 Å.
Influence of the Thermal Vibrations of the Crystal Lattice upon the Energy Distribution of Scattered Ions
Authors: Mashkova E. S. , Molchanov V. A. , Soshka V. 
Published: July 2007

AbstractA study is made of the effect of thermal lattice vibrations on the energy spectra of ions scattered by a Ni crystal. The intensities of the double‐scattering peaks are found to decrease with an increase in the target temperature.
The Effect of a Magnetic Field upon Illuminated InAs p‐n Junctions
Authors: Mikhailova M. P. , Nasledov D. N. , Slobodchikov S. V. 
Published: July 2007

AbstractA study is made of variations in photoresponse with strength of magnetic field in unbiased and reverse biased InAs p‐n junctions. This provides information on the combined effect of electric and magnetic fields, and illumination on p‐n junctions. The curves of photo‐electro‐magnetic e.m.f. against magnetic field strength for reverse biased p‐n junctions show linear inversion‐free regions. The results are analysed on the basis of the theory of the PEM effect in p‐n junctions.
Effect of State on the Shape of the Dislocation Rosette near an Indentation in Some Alkali Halide Crystals
Authors: Pariiskii V. B. 
Published: July 2007

AbstractThe structure of a dislocation rosette near an indentation in KBr and KCL crystals is studied. The motion of dislocations out of the rays of the dislocation rosette due to external impulse stress is shown to depend on the amplitude and duration of the pulse. The effect of stress on the shape of the dislocation rosette near the indentation is shown for KBR, KCI, and NaCI single crystals. During indentation of the stressed crystal the uniaxial surface contraction elongates the rosette rays that adjoin the direction of contraction, whereas the uniaxial dilation elongates the rays that adjoin the direction normal to the direction of extension. The effect is enhanced by increasing the preliminary stresses on the surface to be indented. The observed phenomenon is explained qualitatively by considering the structure of the rosette near the indentation. This effect may be used to determine the magnitude and sign of the local residual elastic stresses at the surface.
On the Theory of Surface and Impurity States
Authors: Levine R. D. , Amos A. T. 
Published: July 2007

AbstractA formalism is developed for perturbation theory in which the Hamiltonian is resolved as H = H0 + V1 + V2 and the two perturbing potentials V1 and V2 are not treated in a symmetric fashion. All the operators are expressed in the H0 representation so that the formalism has particular applications in the theory of impurity states and surface and chemisorption states since H0 can be taken as that part of the Hamiltonian which acts on individual atomic sites, V1 the interatomic interaction and V2, which will have only a small number of non‐zero matrix elements, the effect of the surface or impurity atoms. These applications are illustrated using the linear chain as a model for a one‐dimensional crystal, and the present theory allows the results to be obtained in a very simple way.
Green's Function Method for Energy Band Calculations Including Spin‐Orbit Coupling
Authors: Treusch J. 
Published: July 2007

AbstractThe Green's function method proposed by Korringa, and Kohn and Rostoker, is modified to include spin‐orbit coupling. The formalism follows Korringa's work, and involves solving the two‐dimensional Pauli equation with the condition that the wave function be continuous. The computer time needed is comparable to the case in which spin is not included, as the structure constants are the same in both cases.
Transmission Electron Microscope Study of Brazil Twins and Dislacations Experimentally Produced in Natural Quartz
Authors: McLaren A. C. , Retchford J. A. , Griggs D. T. , Christie J. M. 
Published: July 2007

AbstractTransmission electron microscopy has been used to examine single crystals of natural quartz which have been plastically deformed in compression at high temperature (500 to 700°C) and confining pressure (15 to 20 kbar) with high shear stress on (0001). In specimens deformed at 500°C, the only features found are closely spaced pairs of planar defects parallel to {0001}. Study of the diffraction contrast fringes reveals that each pair of defects bounds a Brazil twin band which has been produced by the high shear stress. At the higher temperature there are dislocations in the twin bands and other regions of the crystals with dislocations only. The dislocations are almost invariably either pure screw (b = a 〈1120〉) or of a particular mixed character (predominantly edge, but with a 30° screw component). Arrays of the mixed dislocations are observed which would produce stress fields consistent with the stress‐optical effects observed by optical microscopy.
On the Theory of Electro‐Absorption and Electro‐Reflectance in Semiconductors
Authors: Enderlein R. , Keiper R. 
Published: July 2007

AbstractThe dielectric response of a semiconductor in a static electric field is investigated. The dielectric function is found to be an integral operator. It should be possible to confirm experimentally the predicted generation of “harmonics” displaced with respect to the frequency of the incident light by an integer times the Zener oscillation frequency.
The Effect of Applied Electric Field on Diffusion of Impurities in Gallium Arsenide
Authors: Boltaks B. I. , Dzhafarov T. D. 
Published: July 2007

AbstractElectrical migration of lithium and copper in gallium arsenide is studied. It is shown that lithium (between 740 and 980°C) and copper (between 820 and 1000°C) migrate in n‐type gallium arsenide as positive ions with a charge of less than +1. The decrease of the ionic charge is due to ion drag by the electrons. In heavily doped p‐type gallium arsenide, copper again migrates in the form of positive ions but in this case with a charge close to +1. This is due to the ion drag by the electrons being almost balanced by the drag from the holes which acts in the opposite direction. Experimental evidence suggests that thermal conversion in gallium arsenide is caused by copper diffusing from outside. Copper can be successfully removed from specimens by heating them in an applied dc electric field. Electrical migration of zinc and cadmium is also studied. Cadmium is shown to migrate in the form of positive ions. In the temperature range 830 to 1130°C, zinc also migrates as positive ions, the effective mobility decreasing with temperature. This temperature dependence of the mobility is in agreement with a theory of the ion drag effect.
Lattice Dynamics of MgO
Authors: Verma M. P. , Dayal B. 
Published: July 2007

AbstractA phenomenological model developed by the author in an earlier paper [1] is applied to the case of MgO. The two‐phonon combined density of states (C.D.S.) is computed from the calculated frequencies. The C.D.S. peaks show good agreement with the subsidiary maxima in the infrared absorption spectrum of the solid. The calculated dispersion curves agree with Pekham's measurements except for the large wave‐vector region, and the specific heats agree with the experimental observations of Barron et al.
The Pair Distribution Function in the R.P.A. and in the Hubbard Approximation
Authors: Brouers F. 
Published: July 2007

AbstractThe pair distribution function of the metallic electron gas is calculated exactly in the R.P.A. and in the Hubbard approximation. The results obtained are discussed and compared with those of previous approximate calculations and a slight modification to Hubbard's interpolation method is proposed.
Heat Capacity and Structure of Vitreous Silica and Diamond‐Like Lattices (I)
Authors: Tarassov V. V. 
Published: July 2007

AbstractThe phonon spectra of lattices with crystalline and glassy structures possessing skeletons of the purely covalent or ionic‐covalent type are discussed on the basis of the “one‐dimensional‐three‐dimensional model”. The upper frequency band, from ω′ to ωmax (ω′ ≪ ωmax), corresponds to a one‐dimensional frequency distribution g1(ω) in which elastic waves may propagate only in certain principal directions. In the lower band from 0 to ω′, the frequency distribution g3(ω) is three‐dimensional, as in the usual Debye‐Born‐von Karman theory. For the one‐dimensional distribution g1(ω) the exact solution is used and taken from papers by Pirenne and Renson, Deltour and Kartheuser for monoatomic and diatomic chains. The phonon spectrum for vitreous silica is discussed in terms of the present model, since its structure resembles that of β‐cristobalite. It is shown that the “chain model” applies to the thermal capacity of vitreous silica up to 900 °K.
Heat Capacity and Structure of Vitreous Silica and Diamond‐Like Lattices (II)
Authors: Tarassov V. V. 
Published: July 2007

AbstractIn a diamond‐like covalent lattice, and in vitreous silica, the phonon spectrum for the main high‐frequency band (containing 80 to 90% of all the modes of vibration) is one dimensional. This leads to the proposed chain model of Tarassov, Pirenne and Renson, and Deltour and Kartheuser. This model is used here to calculate the specific heat of germanium by using the data of Brockhouse and Iyengar. The same method is also applied to InP, AlSb, and vitreous silica.
X‐Ray Diffraction by Hexagonal Close‐Packed Crystals Containing Extrinsic Stacking Faults
Authors: Lele S. , Anantharaman T. R. , Johnson Ch. A. 
Published: July 2007

AbstractThe diffraction pattern for a hexagonal close‐packed (h.c.p.) crystal containing extrinsic stacking faults is derived under the assumption that the crystal is infinite in size with faults covering entire basal planes and distributed at random. While deformation faults broaden reflections with H – K ≠ 0 mod 3, L = 0 mod 2 and H – K ≠ 0 mod 3, L = 1 mod 2 equally and growth faults broaden the former twice as much as the latter, extrinsic faults are shown to broaden the latter only. The broadening due to extrinsic faults is symmetric without any shift of the peak position, as in the cases of deformation and growth faulting.
Die Beobachtung magnetischer Strukturen von Supraleitern zweiter Art
Authors: Träuble H. , Essmann U. 
Published: July 2007

AbstractDurch Aufdampfen kleiner ferromagnetischer Partikel mit Durchmessern von etwa 100 Å auf Blei‐Indium‐Kristalle (χ = 1,2 bei 1,1 °K) wurde die magnetische Struktur im Mischzustand bei 1, 1 °K abgebildet und mit Hilfe von Abdruckverfahren elektronenmikroskopisch beobachtet. Unter günstigen Bedingungen liefert diese Methode ein Auflösungsvermögen von etwa 100 Å. Der magnetische Fluß dringt in diskreten Punkten mit einem Durchmesser von etwa 1000 Å durch die Probenoberfläche. Die Mehrzahl der Punkte ist in unregelmäßiger Weise zu Bündeln von etwa 30 Punkten vereinigt. Mit steigendem Feld nimmt die Zahl der Bündel zu und der Bündeldurchmesser ab. Identifiziert man die einzelnen Punkte mit Austrittsstellen einzelner Flußlinien, die jeweils ein Flußquantum tragen, so ergibt sich im Rahmen der zu erwartenden Genauigkeit befriedigende Übereinstimmung zwischen elektronenmikroskopischen Beobachtungen und gemessenen Magnetisierungskurven. Beobachtungen an dünnen Blei‐Indium‐Scheiben von 0,5 mm Dicke weisen auf die Existenz eines Zwischenzustands bei Supraleitern zweiter Art mit kleinem χ hin.
Conduction Band Structure of Cd0.1Hg0.9Te
Authors: Galazka R. R. , Sosnowski L. 
Published: July 2007

AbstractThe Hall coefficient RH and the conductivity σ are measured in the temperature range 4.2 to 300 °K. The thermoelectric power α as a function of the magnetic field and temperature are measured in the range 100 to 300 °K. The value of the effective mass mast; is calculated from these measurements for electron concentrations from 6.25 × 1016to 2.71 × 1018cm−3. The dependence of the effective mass mast; on k is interpreted according to Kane's model of the conduction band structure. The best agreement is obtained for values of the parameters ε0 = εΓ6 – εΓ8 = −0.00 eV and the coupling constant Q = 12 eV, that is for a linear ε vs. k dependence. The mobility of the electrons as a function of concentration and temperature is also analyzed. For temperatures below 77 °K impurity scattering is dominant. Within the temperature range 77 to 300 °K the best agreement between theory and experiment is obtained for mixed ionic and optical phonon scattering.
EPR Investigations on Mn2+‐Doped LiF Single Crystals
Authors: Böttcher R. , Windsch W. , Lüdke W. 
Published: July 2007

AbstractA discussion is given of the EPR spectra of Mn2+ in LiF single crystals doped with MnF2 both in the melt, and by diffusion. There are two complexes, having orthorhombic and axial symmetry respectively. An explanation is given of the super‐hyperfine structure. It is shown that diffusion of Mn2+ ions into LiF single crystals can occur, and that the behaviour of such diffused ions is largely similar to that of ions incorporated into the crystal in the melt.
Röntgenographische Messung der charakteristischen Debye‐Temperatur bei vielkristallinem Silber mit Anwendung der Korrektur auf primäre Extinktion
Authors: Šedivý J. , Šíachová H. 
Published: July 2007

AbstractDie Debye‐Temperatur Θ von polykristallinem Silber wird aus Röntgenstrahlenbeugungsmessungen bestimmt, die nur bei Zimmertemperatur durchgeführt wurden. Die Methode (unter der Bezeichnung „single‐temperature method”︁ bekannt) beruht auf einer relativ genauen Korrektur der ursprünglichen Extinktion. Sechs auf verschiedene Weise präparierte polykristalline Silberproben wurden untersucht. Der Mittelwert aus diesen Messungen ergibt einen Wert für Θ von (220 ± 8) °K. Die Differenzen zwischen den Θ‐Werten der verschiedenen Proben werden diskutiert, wobei berücksichtigt wird, daß jede Probe zehnmal untersucht wurde.
On the Phenomenon of Selenium Vitrification
Authors: Dzhalilov S. U. , Rzaev K. I. 
Published: July 2007

AbstractThe temperature range for the vitrification of selenium (18 to 36 °C) is determined from volumetric measurements. This is correlated with that obtained from data on the temperature dependence of the viscosity (the function aT), the specific heat, and the velocity of propagation of ultrasonic waves in selenium. It is shown for the first time that the vitrification temperature Tg of selenium depends on the experimental time base. A drop in the cooling rate of two orders of magnitude (from 0.5 to 0.005 deg/min) cause the Tg value to be decreased by 9 °C. Increasing the concentration of Te in selenium lowers the vitrification temperature of the SeTe co‐polymer according to a linear relation. The vitrification temperature of the specimen increases linearly with the concentration of Sb in selenium. This is explained as being due to the binding action of Sb, which consists of the formation of chemical cross‐links between the selenium molecules.
Anhysteretic Magnetization of a Collective of Magnetic Single‐Domain Particles
Authors: Straubel R. 
Published: July 2007

AbstractA theoretical study is made of an ensemble of uniaxially anisotropic, completely aligned single‐domain particles, in which the particles are arranged in linear chains with positive or negative interaction. It is shown that the ensemble is in a true energetic equilibrium with small dc fields after an anhysteretic magnetization process. In this case the ensemble corresponds to an Ising‐model of equivalent spin arrangement. Hence the anhysteretic remanence curve of the ensemble in its initial part, and the anhysteretic initial susceptibility of both types of interaction are estimated.
On Stacked Screw Dislocation Arrays in an Anisotropic Medium
Authors: Chou Y. T. 
Published: July 2007

AbstractA direct method is presented for finding the distribution of dislocations in uniformly stacked arrays in an anisotropic medium. A simple procedure for evaluating the stress field is given. The analytic technique is applied to a special case of an infinite sequence of identical double‐ended pile‐ups stacked one above the other. In this case, the number of dislocations in each of the pile‐ups is found to be less than that in an isolated pile‐up and decreases continuously as the separation between pile‐ups decreases. The stress concentration around the tips of each array behaves in a similar manner. It is shown that the system is elastically equivalent to a vertical array of parallel shear cracks.
Equation of State of Solid Argon and Krypton
Authors: Gupta N. P. , Dayal B. 
Published: July 2007

AbstractThe equation of state, thermal expansion, and isothermal compressibilities of solidified argon and krypton are studied in the harmonic approximation. An exponential interatomic potential is used, and zero‐point quantum effects are included. There is good agreement between the calculated and the observed values.
AC Conductivity of a Glass Semiconductor
Authors: Hench L. L. , Jenkins D. A. 
Published: July 2007

AbstractThe ac conductivity of a 70 mol% V2O5−30 mol% P4O10 glass semiconductor has been measured over a frequency range of 20 to 2 × 1066 Hz and a temperature range of −23 to 200 °C. An activation energy of 0.34 eV was measured over the entire temperature range for frequencies up to 5 × 104 Hz. Below a transition temperature of 70 °C the activation energy for high frequency conduction decreased with increasing frequency.
Positron Annihilation in Alnico and (La0.7Pb0.3)MnO3
Authors: Chuang S. Y. , Hogg B. G. 
Published: July 2007

AbstractA study of the angular correlation of annihilation photons from positrons annihilating in alnico and single crystals of the perovskite (La0.7Pb0.3)MnO3 has been made. It is possible to account for the observed angular distributions by a simple‐minded consideration of the physical properties of the two materials.
Twinning Processes in the Electrocrystallization of Face‐Centred Cubic Metals
Authors: Pangarov N. A. 
Published: July 2007

AbstractA theory is developed for the twinning process in face‐centred cubic crystals. The Stranski‐Kaischew method of average works of separation is used to calculate the work of formation of normal two‐dimensional nuclei on the (111) plane, and of nuclei in the twinning position. The percentage probability for formation of twinning nuclei is calculated as a function of supersaturation. The theory is applicable both to crystallization from the vapour and to metal electro‐deposition.
Electric Conductivity Studies of p‐GaTe Polycrystals and Single Crystals in Strong Electric Fields
Authors: Abdullaev G. B. , Guseinova E. S. , Tagiev B. G. 
Published: July 2007

AbstractIt is shown that in the temperature range 77 to 220 °K and under fields increasing to 3 × 104 V/cm, conduction both of polycrystalline p‐GaTe and of the single crystal increases according to Frenkel's formula \documentclass{article}\pagestyle{empty}\begin{document}$ (\sigma = \sigma _0 \,{\rm e}^{\beta \sqrt E }) $\end{document}. From the formula \documentclass{article}\pagestyle{empty}\begin{document}$ \beta = \frac{{\sqrt {e^3 } }}{{kT\sqrt \varepsilon }} $\end{document} and by determing the slope of the isotherms lg σ=f(√E), the dielectric constants of p‐GaTe, pertaining to the electric part of polarization, are found to be equal to six and four both along and the layers, respectively. By extrapolating with respect to the cross‐over point of isopotentials lg σ = f(1/T), the metallization temperature TM = 20000 °K is determined, from which the value of kTM = 1.74 eV is found. This agrees with the value for the gap width of p‐GaTe at absolute zero. By extrapolating the isotherms and finding a consistent solution to thier equation for the electric strength, a value is obtained which is approximately equal to 6.5 × 105 V/cm.