bluuebunny/crossref_metadata_2025 huggingface dataset:
Equation of State of Solid Argon and Krypton
Authors: Gupta N. P. , Dayal B.
Published: July 2007

The 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

The 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

A 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.
Oscillatory Thermomagnetic Effects in Lead Telluride
Authors: Coste G.
Published: July 2007

Quantum oscillations of the thermoelectric power and thermal conductivity coefficients are observed in p‐type lead telluride (p = 3.6 × 1018 cm−3) at 4.2 °K and up to 50 kG.
Twinning Processes in the Electrocrystallization of Face‐Centred Cubic Metals
Authors: Pangarov N. A.
Published: July 2007

A 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

It 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.
Some Remarks to the Crystal Field Theory of Spinel Lattices
Authors: Jäger E. , Perthel R.
Published: July 2007

The crystal field potential of an octahedral site in the lattice of a normal, and an inverse spinel is calculated on the basis of the point charge model. The ten nearest neighbouring environments are taken into account. Finally, the tables of the matrix elements of the operator equivalents O and O for J = 1/2, 1, 3/2, …, 8 are given.
Electron Transmission Microscopy of NiAl
Authors: Lautenschlager E. P. , Tisone T. C. , Brittain J. O.
Published: July 2007

An electron transmission study of the β‐phase of NiAl was made in annealed and deformed samples with the purpose of looking for antiphase boundary (APB), networks, and super‐dislocations and to observe other configurations of the deformed state. No “grown in” APB networks, superdislocations, or APB trails were observed in annealed or deformed samples. It was concluded that in β‐NiAl APB do not exist and the material deforms on slip systems which do not require the motion of superdislocations. Deformation appears intimately related to tangles of single dislocations, subgrains, tilt and twist subboundaries, distorted hexagonal networks, and dislocation loops.
Some Optical Properties of Thin Evaporated Cd3As2 Films
Authors: Żdanowicz L.
Published: July 2007

The refractive index and absorption coefficient of thin evaporated Cd3As2 films are determinded from spectrophotometric transmission and reflection measurements over the range 0.5 to 12 μm. The refractive index of Cd3As2 is 4.6 at λ = 12 μm; at λ = 1.9 μ a maximum index of nmax = 5.3 is observed. In the spectral region 0.5 to 2 μm a sharp decrease is observed in the absorption coefficient, of about two orders of magnitude, from 105 cm−1 to 103 cm−1, which may be due to direct transitions. In the range 6 to 12 μm, the absorption coefficient again falls to about 102 cm−1, which probably corresponds to indirect transitions. The results obtained may explain the discrepancies in the values of energy gap quoted by different authors for Cd3As2.
Diffusion of Nickel in Silicon
Authors: Bonzel H. P.
Published: July 2007

The study of diffusion of nickel (Ni63) in silicon single crystals in the temperature range 450 to 800 °C supports the “dissociative diffusion mechanism” for this impurity. Rapid interstitial diffusion of Ni into Si is followed by a complex reaction of interstitials with vacancies resulting in particular concentration profiles of substitutional nickel. The production and diffusion of vacancies which has a great influence on this reaction, is discussed. The activation energy for diffusion of vacancies has been estimated to 44 kcal/mol and the self‐diffusivity in silicon can be approximately described by.
The Influence of Large Elastic Anisotropy on the Determination of Burgers Vectors of Dislocations in β‐Brass by Electron Microscopy
Authors: Head A. K. , Loretto M. H. , Humble P.
Published: July 2007

The theory of electron diffraction images of dislocations based on isotropic elasticity is found to be inadequate for β‐brass because of its large elastic anisotropy. In particular, the isotropic invisibility criteria (g · b = 0 and g · b × u = 0) are not valid in general in anisotropy except for pure screw or pure edge dislocations lying perpendicular to a symmetry plane of the crystal. Theoretical image profiles have been computed using the two‐beam dynamical approximation and the full anisotropic strain fields of dislocations. Comparison of the character of theoretical and experimental images has established that the majority of dislocations in β‐brass are screw dislocations having a Burgers vector of a whole 〈111〉 and gliding on {110}.
The Identification of Burgers Vectors and Unstable Directions of Dislocations in β‐Brass
Authors: Head A. K. , Loretto M. H. , Humble P.
Published: July 2007

The theoretical predictions of electron microscope images of dislocations in anisotropic crystals described previously are extended to identify other dislocations in β‐brass. Many dislocations having sharp bends are observed. Their Burgers vectors are 〈111〉 and their crystallography agrees well with the predicted instability of such dislocations. Dislocations of Burgers vector 〈100〉 have also been identified, lying on both {100} and {110} planes. Some dislocations with Burgers vectors 〈111〉 can be shown to be split into two ½ 〈111〉 dislocations with an ordering energy of ≈︁ 40 erg/cm2.
Thermomagnetic Effects in Anisotropic Media
Authors: Pinchuk I. I.
Published: July 2007

Components of the thermomagnetic tensor for arbitrary orientation of the magnetic field H and any crystallographic structure are analysed, and the case of weak magnetic fields is examined. Tensor components are arranged as powers of the magnetic field up to and including third order terms. Non‐zero expansion coefficients, and the relations between them, are tabulated.
Some Observations on the Cr3+ Fluorescence in the Huntite Structure
Authors: Blasse G. , Bril A.
Published: July 2007

Absorption and emission spectra of Cr3+‐activated huntites of the type Ln3+Me3+3B4O12 (Ln = Y or Eu, Me = Al or Ga) are reported. For the aluminium and gallium compounds the crystal field splitting of the Cr3+ ion is about equal, but the electrostatic interaction parameter B is different. The Cr3+ emission of these compounds, unlike the emission of ruby, consists of lines and bands. In EuAl3B4O12:Cr, nonradiative energy transfer from Eu3+ to Cr3+ is observed; in YGa3B4O12: Cr nonradiative energy transfer occurs from the host lattice (probably GaO6 groups) to Cr3+.
Mössbauer Effect in Iron‐Aluminium Alloys (I)
Authors: Cser L. , Ostauevich J. , Pál L.
Published: July 2007

The ordering process and magnetic structure of iron‐aluminium alloys near the composition Fe3Al are studied experimentally by the Mössbauer technique. It is found that the isomer shift shows a pronounced hysteresis in the temperature range 750 to 850 °C which indicates the first order character of the B2‐type ordering. The simultaneous appearance of the central (paramagnetic) and hyperfine lines in the temperature interval 640 to 500 °C shows that the Mössbauer spectrum is a superimposition of two spectra. These originate from Fe57 nuclei on two different sublattices; one of them is paramagnetic (A sublattice) and the other is magnetically ordered (D sublattice). The hyperfine field and the isomer shift of the hyperfine lines show a pronounced discontinuity at the temperature of the DO3‐type ordering. At this temperature it is found the intensity ratio of the outer to adjacent peak also suffers a sudden change. This indicates a ferromagnetic to antiferromagnetic transformation which is not contrary to existing theoretical ideas but as yet lacks direct experimental confirmation.
Interaction of Optical Phonons with Spin Waves in Ionic Crystals
Authors: Casselmann T. N. , Spector H. N.
Published: July 2007

Optical phonon effects on the magnon resonance (FMR and AFMR) are shown to be negligible in ferromagnetic insulators and most antiferromagnets in present day laboratory fields (H ⪅ 2 × 105 G). In these fields the magnon frequency lies lower than the optical phonon frequency so that the coupling is to a polarization mode which is mainly photon‐like. However, at the band edge, the wavelength‐dependence of the magnon and optical phonon dispersion may allow crossing in low fields. Also, in metamagnetic systems where the anisotropy field is much larger than the exchange field, the resonance in the paramagnetic phase may occur in a frequency range such that the polarization mode will contain a relative large fraction of optical phonons. The theory developed in this paper can also be applied to optical phonon‐spin resonance in paramagnetic salts. This type of resonance should occur in attainable magnetic fields for materials with large g factors.
Wavy Fringes at Domain Boundaries in Barium Titanate Observed in the Electron Microscope
Authors: Remaut G. , Gevers R. , Amelinckx S.
Published: July 2007

A series of numerically calculated fringe profiles shows that images of zig‐zag fringes superposed on wavy fringe patterns in BaTiO3 result from three superposed ferro‐electric domain walls. The two outer walls being 90° boundaries, while the central interface is a 180° boundary which, in order to decrease the electrostatic energy, “meanders” between the two 90° walls.
Über das Kriechverhalten von NaCl‐Einkristallen
Authors: Blum W. , Ilschner B.
Published: July 2007

Die stationäre Kriechgeschwindigkeit von NaCl‐Einkristallen wurde in Abhängigkeit von der Temperatur, der Belastung und dem Verformungsgrad im Druckversuch gemessen. Die Auswertung stützt sich vor allem auf eine theoretisch begründete Darstellung der Meßwerte als log (dε/dt) = f(ε). Dynamisches Gleichgewicht zwischen Verfestigung und diffusionsgesteuerter Erholung (Klettern von Stufenversetzungen) vermag das beobachtete Verhalten zu deuten. Wesentliches Element der quantitativen Auswertung der Kriechversuche (mit und ohne Schmierung durch Glasfolien) ist die Berücksichtigung der Probenformänderung während der Verformung.
Electron Spin Resonance of Co2+ Ions in Barium Titanate
Authors: Žďanský K. , Arend H. , Kubec F.
Published: July 2007

The ESR of Co2+ ions in the slightly deformed octahedral field of BaTiO3 single crystals is observed. The values of the isotropic parts of the g‐factor and the hyperfine parameter A are determined from the spectra. The effect of thermal treatment in oxygen and hydrogen atmospheres is observed. The measured values of the g‐factor and of the hyperfine parameter A are discussed and compared with the values of these parameters in MgO crystals.
The Theory of Stability during Temperature Gradient Zone Melting
Authors: Delves R. T.
Published: July 2007

First, a dynamic theory is given for the stability of a melting interface when there is a segregating component. Stability during temperature gradient zone melting is analysed to first order in the amplitude of the intial disturbance, assuming infinite thermal conductivity. This case is also discussed with the addition of nucleation kinetics at the interfaces, and slowly developing instabilities are found in most cases. Thermal effects are included and are found to modify but not remove the instabilities whose wavelength is longer than the zone thickness. However, if the wavelength is shorter than the zone thickness an instability may develop rapidly unless the interface free energy is sufficient to stabilize the interfaces. This conclusion has been found previously by Seidensticker. The conditions for avoiding the fast instability are thin zones and small temperature gradients.
Luminescence of CdS Excited by Electrons of Various Energies
Authors: Egorov V. D.
Published: July 2007

Luminescence spectra of spontaneous and stimulated emission are investigated for CdS‐crystals excited by electrons with energies between 15 and 150 keV at liquid nitrogen temperature. Selfabsorption is shown to affect the spectral distribution of the radiation from the excited surface. The dependence of the luminescence intensity on the beam current density is measured.
Observations of Ferromagnetic Domains by Anomalous Transmission of X‐Rays. The Effects of Variation in the Reflecting Plane
Authors: Roessler B.
Published: July 2007

The ferromagnetic domain patterns observed by anomalous transmission of X‐rays in Fe–3% Si crystals grown by secondary recrystallization are shown to depend on the choice of reflecting plane. The {110} reflection shows straight lines in the 〈100〉 directions which are sometimes resolved as zig‐zag lines. The {200} reflections show surface closure domains which are the same as those seen in Bitter patterns; zig‐zag boundaries and several other features are also seen. The importance of strain effects in determining the domain pattern is discussed.
Magnetic Properties of NaNiF3
Authors: Judin V. M. , Sherman A. B.
Published: July 2007

The static magnetic properties of a single crystal of NaNiF3 (space group Pbnm) are investigated in the temperature range 77 to 300 °K. The Néel temperature, TN = 156 °K, is determined and the temperature dependences of the magnetic susceptibilities along different crystallographic directions are investigated. The spontaneous magnetic moment is observed only along the c‐axis in fields of up to 18 kOe at 77 °K. The results obtained are discussed within the framework of the thermodynamic theory of weak ferromagnetism. The anisotropic superexchange appears to be most probable mechanism for the origin of weak ferromagnetism in NaNiF3. A departure of the temperature dependence of the spontaneous moment from the respective Brillouin function is observed.
Investigation of the Quasi‐Local Level in the Vibrational Spectrum of the Ti Lattice with Heavy Impurity Atoms
Authors: Chernoplekov N. A. , Panova G. Kh. , Zemlyanov M. G. , Samoilov B. N. , Kutaitsev V. I.
Published: July 2007

A quasi‐local level appears in the vibrational spectrum of a titanium lattice containing 5 at % of uranium. This is investigated both by neutron inelastic scattering techniques and by measuring the low‐temperature heat capacity. The results obtained are found to be in satisfactory agreement with theoretical calculation.
On the Mechanism of Thermal Conductivity in (GaSb)3x–(Ga2Te3)1–x and (GaSb)x–(GaTe)1–x Solid Solutions
Authors: Abdurakhmanova A. A. , Aliev M. I.
Published: July 2007

Measurements are made of the thermal conductivities of (GaSb)–(Ga2Te3)1–x and (GaSb)x–(GaTe)1–x Solid Solutions as a function of composition and temperature (80 to 550 °K). Decrease of x as a function of composition is caused by the strong scattering of phonons on the distortion of lattice periodicity and defects. The thermal resistance is produced by 3‐phonon processes. In the alloys with high concentration of defects x does not depend on T in the temperature range T > 350 °K. (The mean free path of phonons is li ≦ a, where a is the lattice constant.) The additional thermal resistance observed in all alloys is caused primarily by phonon scattering oil the defects. Provided a linear frequency dependence of the relaxation time of N‐processes good agreement of experimental results with theory is observed.
The Penetration Depth in Two Band Model Superconductors
Authors: Radhakrishnan V.
Published: July 2007

The experimental results of Maxfield and McLean for the variation of penetration depth λL(T) with temperature for niobium cannot be explained in terms of the usual BCS model of superconductivity. It is shown that better agreement can be obtained on the basis of the twoband model, proposed by Suhl, Matthias and Walker, for transition element superconductors.
Veränderungen an reinen Platinoberflächen durch gelöste Fremdstoffe: Beobachtungen mit dem Feldelektronenmikroskop
Authors: Vanselow R.
Published: July 2007

Im FEM wurden Spitzen aus spektralreinem Pt bei p < 1 × 10−9 Torr ohne Feld getempert. Unterhalb 500 °C blieb das durch geeignete Vorbehandlungen erzielte Bild der reinen Oberfläche erhalten. Oberhalb 500 °C bewirkten zur Spitzenkalotte diffundierende, aus dem Pt stammende Fremdstoffe Veränderungen. Bis ca. 1350 °C wurde eine reproduzierbare Folge sehr verschiedener Bilder durchlaufen, deren charakteristische Merkmale im wesentlichen von der Spitzentemperatur und meist nur wenig von der einige Minuten betragenden Temperdauer abhingen. Auf Grund bekannter flächenspezifischer Reaktionen bzw. Anlagerungen konnte ein Teil der Merkmale auf die Anwesenheit von Sauerstoff und Eisen zurückgeführt werden. Nach vorliegenden Analysen mit dem Feldionen‐Massenspektrometer ist weiterhin mit dem Vorliegen von Kupfer zu rechnen [1].
Second Order Conductivity and Nonlinear Plasma Excitation of an Isotropic Electron Gas
Authors: Stolz H.
Published: July 2007

The theory of the second order conductivity tensor of an isotropic electron gas is developed using thermodynamic Green's functions. It is shown that this quantity is exactly determined by the first order conductivity tensor and an additional term consisting of a pure three‐current correlation function. This term is found to be small in the optical and plasma regions. The second order conductivity tensor is calculated in the Hartree approximation. The poles of the second order response function relating the induced particle density to a scalar external potential are discussed and shown to yield the second and zeroth harmonics of the ordinary plasma waves as determined by the linear response of the system. For the special case of shock excitation by a Coulomb potential, semiquantitative arguments are presented in favour of a non‐negligible second order contribution to the total density response which may possibly also contribute to the energy loss of fast electrons in metals.
Effect of Current Carrier Scattering on the Complex Dielectric Tensor
Authors: Zyryanov P. S. , Okulov V. I.
Published: July 2007

A general expression is derived for the scattering‐dependent complex conductivity tensor σα β(ω, q). The density matrix satisfying the local charge and energy conservation laws in the presence of an electromagnetic field, is calculated in a linear approximation with respect to the carrier‐field interaction. It is shown that the conductivity tensor involves the term Δσαβ which vanishes if either the spatial dispersion or the scattering is not considered. In a high non‐uniform magnetic field at low frequencies the term gives rise to the conductivity current. If the orbital quantization is essential Δσαβ causes the diamagnetic susceptibility to become frequency‐dependent.
Temperature Dependence of Hyperfine Structure Tensors of Diatomic Halogen Centres in Alkali Halide Crystals
Authors: Dreybrodt W.
Published: July 2007

The ESR‐spectra of diatomic halogen centres of the type X and XY− in alkali halides show temperature dependent line positions due to changes of the hfs‐constants. The temperature dependent part of the hfs‐tensors is determined from an analysis of these spectra. The mechanisms leading to the temperature dependence are discussed: crystal lattice vibrations and resonant vibrations of the molecule modulate the crystal field. This lowers the electron density at the nuclei of the molecule as the vibrational amplitude increases. The frequencies of the molecular vibrations are determined from the experimental data. The effect of the lattice on the force constants is discussed with reference to the comparison of these values with those for the corresponding free molecules.
An X‐Ray Diffraction Study of Rubidium Chloride
Authors: Järvinen M. , Inkinen O.
Published: July 2007

Absolute X‐ray intensity measurements are made of Bragg reflexions from rubidium chloride powders at 300 °K by direct measurement of the intensity of the primary beam. It is found that the effects of preferred orientation, surface roughness, and extinction are negligible. Values for the temperature parameters of BRb = (2.28 ± 0.10) Å2 and BCl = (2.44 ± 0.10) Å2 are obtained; these correspond to the Debye temperature Θ = (157 ± 4) °K. The values of the crystal radii of the ions are found to be RRb = (1.71 ± 0.05) Å and RCl = (1.58 ± 0.05) Å. Deviations from spherical symmetry are revealed in the outer electron distribution of the chlorine ions. Throughout the entire angular range examined, the average trend of the experimental scattering factors of both ions is found to coincide with the theoretical free‐ion values to within 1.5%.
Measurement of Thermal Parameters of Thin Films and Plane‐Parallel Plates Located on a Thermally Conductive Base
Authors: Budke O. , Krempaský J.
Published: July 2007

A method is developed for measuring the thermal conductivity, thermal diffusivity, and specific heat of thin films and plates located on a thermally conductive base. The method of measurement involves the use of a point or line pulse heat source. Mathematical expressions for the present treatment are derived from the computed solution of the complex transcendental equations. The present method makes it possible to measure the temperature characteristics of samples of thickness h ≧ 10 μm located on a base with a practically arbitrary thermal conductivity and a definite temperature characteristic. However, the computation can easily be extended to include samples of thickness h < 10 μm.
A Possible New Group of Semiconducting Compounds
Authors: George W. P. R. , Goodman C. H. L. , Sterling H. F. , Warren R. W.
Published: July 2007

An extension of the chemical bonding approach to semiconductivity leads to the prediction that certain highly refractory intermetallic compounds could be high mobility semiconductors. Special Czochralski techniques were developed to pull single crystals of titanium and zirconium diboride, which melt in the 3000 °C range. In agreement with the theory, these materials were found to be non‐metallic. The lowest carrier concentration obtained however (6 × 1020 electron/cm3) could not enable a distinction to be made between impurity semiconductor and semimetal particularly as some non‐stoichiometry might be expected from the mode of preparation.
Die elektrischen Eigenschaften von Versetzungen in Germanium
Authors: Schröter W.
Published: July 2007

Die Hallkonstante plastisch verformter, schwach p‐dotierter Germaniumeinkristalle wurde zwischen 50 und 250 °K gemessen. Die elektrisch wirksamen Verformungszentren konnten als Versetzungen identifiziert werden. Während die Trägerdichte bei höheren Temperaturen durch Versetzungsakzeptoren bestimmt ist, beweist die Kompensation chemischer Zentren bei tiefer Temperatur Versetzungsdonatoren. Die Auswertung führt auf ein Versetzungsband, dessen Besetzungsgrenze im neutralen Zustand 0,09 eV über der Valenzbandkante liegt.
Effets galvanomagnétiques et thermomagnétiques classiques dans l'arséniure de cadmium
Authors: Sexer N.
Published: July 2007

Une étude classique des phénomènes de transport dans l'arséniure de cadmium, Cd3As2, a permis de choisir un modèle pour la structure des bandes de conduction de ce composé. Ce modèle comporte deux bandes de conduction, distantes de 0,15 eV et de masses effectives 0,06 et 0,12 m.
Optical Studies of β‐SiC
Authors: Ziomek J. S. , Pickar P. B.
Published: July 2007

The results of a study to characterize samples of single crystals of β‐SiC grown by a modified Czochralski technique are given. The X‐ray diffraction patterns were indexed as a face‐centered cubic lattice whose parameter was a0 = 4.357 Å and showed virtually no twinning. The absorption measurements in the region from 1.5 to 4.0 eV yielded an estimate for the band gap for the indirect transition as 2.60 eV which agree with that obtained from photoconductance experiments. In the region from 0.05 to 0.5 eV room temperature absorption measurements showed absorption bands which could be tentatively assigned as two‐phonon bands. Raman spectrum excited by the 6328 Å line of the HeNe laser showed two bands, one at 795 cm−1 taken as the transverse optical mode, and one at 995 cm−1 taken as the longitudinal mode.
The Effect of Grain Size on the Lattice Thermal Conductivity of Copper Aluminium Alloys
Authors: Salter J. A. M. , Charsley P.
Published: July 2007

Measurement of the lattice thermal conductivities between 1.5 and 4.2 °K of a series of CuAl alloys indicates that there is a term linear in temperature which can be attributed to grain boundary scattering of phonons. The results are compared with two approaches to the kinetic model in which a frequency independent relaxation time for grain boundary scattering is assumed. In the first it is assumed that (Kg)−1 = ΣWi, where the Wi are the thermal resistivities due to each scattering process considered alone. In the second a combined relaxation time for all processes is defined by τ− = Σ τ−1. It is shown that in the latter approximation the model describes the experimental results well.
Light Effects on Space‐Charge Controlled Currents in CdS
Authors: Bräunlich P.
Published: July 2007

The paper describes two types of light effects on space‐charge controlled currents, both observed in CdS single crystals with In as an injecting and Cu2S as a blocking contact: 1. interaction of optically generated electron‐hole pairs with injected carriers; 2. direct optical excitation of trapped space charge. Photocurrents with a superlinear dependence on voltage have been studied. A new negative photoconductivity effect in CdS is also described and explained by a redistribution process of injected holes and electrons.
Two Beam Kinematical Theory for the Diffraction of Electrons by Crystals with Stacking Faults
Authors: Gevers K. , van Landuyt J. , Amelinckx S.
Published: July 2007

The intensity of weak diffraction spots is calculated on the basis of “a two‐beam kinematic” theory. The assumption is made that apart from the incident beam there is one strongly scattered beam. The incident and the strongly scattered beams are considered to interact according to the dynamic theory, but the dynamic interaction between the strongly and weakly scattered beams is neglected. Expressions are developed for the amplitudes and intensities of the weakly scattered beams both for perfect crystals and for crystal slabs containing stacking faults. The theory leads to the prediction that the dark field image of stacking faults taken in a weak diffraction spot should represent the fringe periodicy characteristic of the strongly diffracted beam. This is confirmed by observations. It is suggested that much weaker fringes with spacing characteristic of the s‐value of the weak spots may be superposed on the strong fringes. These fringes have not been observed.
On the Theory of Tunneling
Authors: Serebrennikov P. S.
Published: July 2007

The relation between the I‐V‐curve of the tunneling system and the densities of states on both sides of a junction is investigated for a general case.
The Mechanism of Deformation of the Ordered CuAu Alloy
Authors: Syutkina V. I. , Yakovleva E. S.
Published: July 2007

Electron microscopy techniques are used to study the domain structure and the mechanism of deformation of the ordered CuAu alloy. Investigations are made into the factors impeding the passage of dislocations across the boundary between domains with differently orientated c‐axes. Experiments indicate that the greatest obstacle to the passage of dislocations across such a boundary is the necessity of pairing single dislocations.
Étude expérimentale de la dynamique des domaines de haut champ électrique dans le couplage électron‐phonon
Authors: Ropé J.‐P.
Published: July 2007

Nous étudions la répartition de potentiel à l'intérieur des domaines de haut champ électrique qui se propagent dans les échantillons de GaAs présentant des oscillations de courant dues au couplage électron‐phonon. Nous montrons en particulier que le champ électrique dans le domaine augmente lorsque le domaine disparaît.
Relaxation des domaines de haut champ et émission de lumière associées aux oscillations de courant dans GaAs
Authors: Bonnot A.
Published: July 2007

Une émission de lumière infrarouge a été observée dans des échantillons d'arséniure de gallium de type n, présentant des instabilités de courant résultant du couplage électro‐acoustique. La lumière apparaît lorsque le domaine de haut champ atteint l'anode de l'échantillon. L'émission de lumière prend naissance quand le champ électrique appliqué est supérieur a un certain champ de seuil E0. L′énergie de la lumière est de 1,42 eV à 77 °K et de 1,36 eV à 300 °K. Ces deux valeurs correspondent à la transition bande à bande du semiconducteur, aux températures considérées. Nous pensons que cette émission est liée à une augmentation du champ dans le domaine pendant sa destruction. Nous montrons que lorsque le domaine disparaît son champ électrique peut effectivement augmenter.
Calculations on the Mechanical Energy of Vacancy Condensation Loops, Stacking Fault Tetrahedra, and Voids
Authors: Sigler J. A. , Kuhlmann‐Wilsdorf D.
Published: July 2007

Employing the most accurate theoretical expressions known for the energy of five different types of vacancy condensation products, the relative stabilities of these are evaluated by means of a B 5500 computer. The calculations are performed for the cases of aluminum, nickel, platinum, copper, gold, and silver, while the defects considered are the hexagonal Frank loop on {111} with 1/3 <111> as Burgers vector, two perfect loops with 1/2 <110> Burgers vectors, one of these being hexagonal on {111} the other diamond‐shaped on {110}, further the spherical void and, finally, the stacking fault tetrahedron. By comparing the results of the calculation with experimental evidence, some broad agreement is found, but also some quite important discrepancies. These are discussed theoretically.
On the Thermal Conductivity of CdTe and Some CdTe1−xSx and CdTe1−xSex Solid Solutions
Authors: Kelemen F. , Néda A. , Niculescu D. , Cruceanu E.
Published: July 2007

The thermal conductivity of CdTe and some solid solutions of CdTe1−x Sx and CdTe1−x Sex (x = 0.1 and 0.2) is studied. Measurements are made at temperatures ranging from 90 to 700 °K, on two kinds of monocrystal specimens, prepared from elements of different purity. In specimens synthetized from less pure elements, the thermal conductivity starts to increase with temperature between 300 and 400 °K, whereas in specimens obtained from elements of 99.9999 per cent purity this increase only occurs at higher temperatures (about 500 °K). The additional thermal conductivity in purer specimens may be ascribed to due to ionization of impurities. For impurities in CdTe, the values of ionization energy calculated from the temperature dependence of the thermal conductivity are comparable with those determined by other methods.
Kinetics of Quenched‐in Vacancies in Pure Platinum
Authors: Polák J.
Published: July 2007

The kinetics of the annealing of vacancies in pure platinum quenched in water is investigated. S‐shaped isothermal annealing curves are observed. After an initial transient region the annealing kinetics is approximately second order. Experimental results are discussed by assuming thermal equilibrium to exist between single‐vacancies and di‐vacancies. By using the deviations from purely second order kinetics, and comparing the calculated and measured values of the effective migration energy, estimates are made of the binding energy of a di‐vacancy B2 = (0.18 ± 0.05) eV and the difference between the migration energy of single and di‐vacancies Δ = (0.34 ± 0.05) eV in platinum.
Crystal Structure and Magnetic Properties of Some Rare Earth Germanides
Authors: Buschow K. H. J. , Fast J. F.
Published: July 2007

Magnetic and structural data are determined for eleven rare‐earth germanium compounds with the formula R5Ge3. These compounds are isotypic and have the hexagonal Mn5Si3 type of structure. For R = Pr, Gd, Tb, Dy, Ho, and Er antiferromagnetic behaviour is observed at low temperatures. The antiferromagnetic exchange interaction is weak in these compounds. A field‐induced transition to a magnetic structure with a much higher moment is observed at 4.2 °K for Tb5Ge3, Dy5Ge3, Ho5Ge3 and Er5Ge3. At low temperatures Nd5Ge3 and probably also Ce5Ge3 are ferrimagnetic. The Curie‐Weiss law is obeyed by all these compounds at high temperatures. The observed effective moments are close to those of the free trivalent rare earth ions. La5Ge3 and Y5Ge3 are Pauli paramagnetic.
The Electromagnetic Aspect of Magnetostrictively Induced Torsional Oscillations (the Procopiu Effect with a Cylindrical Ferromagnetic Specimen Fixed at one End)
Authors: Rothenstein B. F. , Policec A. , Lupulescu M. , Anghel C.
Published: July 2007

The Procopiu effect for a cylindrical ferromagnetic specimen fixed at one end, involves the induction of an e.m.f. in a search coil surrounding the specimen when a constant longitudinal magnetic field Hy and an oscillatory circumferential magnetic field Hx are applied simultaneously. It is shown that the shape of the e.m.f. induced in this form of the Procopiu effect differs from that occuring with the same specimen fixed at both ends. Using a constant amplitude for Hx, a study is made of the dependence of the effect upon Hy and upon the phase relations between Hx and the torsional oscillations induced by magnetostriction.
Carrier Recombination in Nickel Doped Germanium from Lifetime and Noise Measurements
Authors: Gouskov L. , Lecoy G. , Llinares C.
Published: July 2007

A study is made in order to precise the transition processes for free carriers between the bands and the well‐controlled deep Ni levels in Ge from 100 to 350 °K. The experimental work involves measurements of the lifetime of the photoconductive decay and the generation‐recombination noise.
X‐Ray Diffraction Contrast on Ferromagnetic Domain Walls in Fe‐Si Single Crystals
Authors: Polcarová M. , Kaczér J.
Published: July 2007

The contrast of ferromagnetic domains in (001) Fe‐3% Si single crystal plates is studied using X‐ray diffraction topography. This contrast is found to be due solely to the difference in deformation on opposite sides of the wall which is produced by magnetostriction. 180° walls are therefore never visible, whereas 90° walls show contrast if diffracting planes not belonging to the zone m2 — m2 are used (m1 and m2 are unit vectors parallel to the magnetization on the two sides of the wall).
Der Flußeintritt in Supraleiter II. Art
Authors: Takács S.
Published: July 2007

Es wird gezeigt, daß in einem makroskopischen Supraleiter II. Art das Auftreten von Flußwirbeln bereits unterhalb des thermodynamischen kritischen Magnetfeldes energetisch günstig und die “reine” Oberflächenbarriere unwirksam wird. Die Werte für das Entstehungsfeld der Wirbel und für die maximale Eintrittsfeldstärke werden für den Halbraum angegeben; im Anhang werden die maximalen Eintrittsfeldstärken für einen dünnen Hohlzylinder angefügt.
Fatigue Hardening of CuZn Alloys
Authors: Lukáš P. , Klesnil M.
Published: July 2007

The initial stage of the fatigue process — fatigue hardening — is studied for three CuZn alloys with different stacking fault energies in the region of low stress amplitudes (lifetimes of order 105 cycles and higher). The study involves both measurements of the mechanical properties in the microstrain region and transmission electron microscopy. All measurements confirm the strong influence of the stacking fault energy on the course of the hardening. Fatigue hardening arises from both short‐range and long‐range stress fields. The contribution of the long‐range stress fields to the total hardening decreases with decreasing stacking fault energy.
The Band Edge and the Energy Spectrum of In2Se
Authors: Bercha D. M. , Borets A. N. , Stakhyra I. M. , Tovstyuk K. D.
Published: July 2007

The absorption coefficient of In2Se is investigated experimentally near the band edge using polarized radiation. The selection rules for the space group D to which In2Se belongs are determined by group‐theoretical methods. An energy‐band model is proposed which agrees with the experimental data.
Study of Barium Adsorption on Germanium by Field‐Emission Microscopy
Authors: Sokolskaya I. L. , Ivanov V. G. , Fursey G. N.
Published: July 2007

The change in work function of barium‐covered p‐ and n‐type germanium emitters with the degree of coverage θ is investigated by FEM. The curve of work function φ against deposition time is similar to that for barium adsorption on metals. The work functions of clean field‐desorbed surfaces of p‐ and n‐type emitters are determined from the Fowler‐Nordheim slopes with respect to that for barium‐covered surfaces, assuming that the work function of the latter for θ > 1 is φBa = 2.5 eV. The work functions are φp = (4.90 ± 0.05)eV and φn = (4.43 ± 0.05) eV for φp = 3.7 Ωcm and Qn = 2.5 ωmcm, respectively. The difference in the observed work functions compares well with the difference of the Fermi level position. Metallic‐like properties of barium on germanium are observed at coverages θ much less than a monolayer (θ = 0.007).
The Properties of the Low‐Temperature Internal Friction Peak in Silicon
Authors: Khiznichenko L. P. , Kromer P. F. , Kaipnazarov D. K. , Otenyazov E. , Yustpova D. , Zotova L. G.
Published: July 2007

The properties of the low‐temperature internal friction peak are studied in n‐silicon single crystals at a frequency of 100 Hz at a temperature of approximately 110 °K. It is shown that annealing at high temperatures suppresses the peak. Maximum increases after plastic deformation. After γ‐irradiation the peak height is found to decrease with dose by an exponential law. These features suggest that the peak is of the Bordoni‐type. Similar internal friction maxima are also observed in n‐type germanium and p‐type silicon single crystals.
Mikromagnetische Behandlung der Wechselwirkung zwischen Versetzungen und ebenen Blochwänden. II. Anwendungen
Authors: Pfeffer K.‐H.
Published: July 2007

Es werden die Änderung der Magnetisierungsverteilung innerhalb und außerhalb der (112)−180°‐Blochwand in Nickel infolge der inneren Spannungen von Einzelversetzungen (Stufen‐ und Schraubenversetzungen), die parallel zur Blochwand verlaufen, und das aus der Spinumordnung resultierende Wechselwirkungspotential zwischen Blochwand und Einzelversetzung berechnet. Die Resultate werden hinsichtlich Größe, Temperaturabhängigkeit und asymptotischem Verhalten mit der Magnetisierungsverteilung und dem Wechselwirkungspotential bei starrem Magnetisierungsverlauf systematisch verglichen. Zur Untersuchung des Einflusses von korrelierten Versetzungsanordnungen auf die Wechselwirkung mit der Blochwand wird die Kraftwirkung von Versetzungsdipolen und Versetzungsgruppen berechnet. Da die aus der Spinumordnung resultierende Wechselwirkung quadratisch von den inneren Spannungen abhängt, ist die von Versetzungsgruppen auf die Blochwand ausgeübte Kraft viel größer, als man bei linearer Superposition der Einzelkräfte erwarten würde. Im Unterschied zu der Kraft, die sich bei Annahme eines starren Magnetisierungsverlaufes berechnet, ist die aus der Spinumordnung resultierende Kraft auch dann noch empfindlich von den Versetzungsabständen abhängig, wenn diese größer als die Blochwanddicke sind.
Zur Theorie der Koerzitivfeldstärke und Anfangssuszeptibilität
Authors: Pfeffer K.‐H.
Published: July 2007

Mit der Theorie der homogenen Zufallsfunktionen werden unter der Annahme, daß die Ummagnetisierung durch reine 180°‐Blochwand‐Verschiebungen erfolgt, die charakteristischen Größen maxKW(z) und (KWist die Wechselwirkungskraft zwischen einer Blochwand an der Stelle 0 ≦ z ≦L3und Gitterstörungen) und damit die KoerzitivfeldstärkeHcund AnfangssuszeptibilitätXaberechnet. Im Unterschied zu der von Träuble bei der Durchführung der statistischen Analyse der Blochwandbewegung angewandten Theorie der statistisch unabhängigen Zufallsvariablen bedarf dieses Verfahren insbesondere zur Berechnung vonXakeiner besonderer Zusatzannahmen. Die hier dargelegte Theorie gestattet es, den Einfluß beliebiger Versetzungsanordnungen aufHcundXain geschlossener und übersichtlicher Form zu untersuchen. Für Versetzungsanordnungen, die aus Versetzungsschleifen bestehen, die in Lage und Form unkorreliert sind, werden Größe und Temperaturabhängigkeit vonHcundXadiskutiert. Die Korrelationslänge, die ein Maß für das ProduktHcXaist, ergibt sich im Unterschied zu den Resultaten der bisherigen Theorie der Koerzitivfeldstärke und Anfangssuszeptibilität im allgemeinen als verformungsabhängig.
Transport Phenomena in Semiconducting Thin Films
Authors: Tavger B.
Published: July 2007

Transport phenomena in thin semiconducting films are studied using the transport equation, the quantization of the transverse motion of the electrons being taken into account. A general formula relating the relaxation time for a thin film to that for the bulk semiconductor is obtained. The mobility is found to increase as the film thickness decreases. Hence the increase of the resistivity with decreasing film thickness does not in general indicate increasing imperfection density. It is found that the Hall constant is only weakly dependent on the film thickness. The transport effects in thin semiconducting films and in bulk semiconductors are compared for several scattering mechanisms.
Waves with Discrete Spectrum in Metals in the Vicinity of the Cyclotron Resonance Frequency
Authors: Blank A. Ya. , Kaner E. A.
Published: July 2007

A theoretical study is made of the cyclotron resonance in metals in an inclined magnetic field caused by the existence of the periodical system of high‐frequency current peaks. Weakly damped electromagnetic waves with a discrete spectrum are found near the resonant frequencies. The excitation of waves with a discrete spectrum leads to the fine structure of the cyclotron resonance line.
Impurity Absorption Bands in Thermoluminescent LiF
Authors: Claffy E. W.
Published: July 2007

Impurity absorption bands in the ultraviolet (1370 and 1960 Å) and infrared (2.8 μm) which may occur in various commercial crystals of LiF cannot be correlated with the thermoluminescence glowpeak at 210 °C, with the Mg or OH− content, or with each other. The present data fail to support the argument that impurity centers absorbing in the 2000 Å region play an essential role in the thermoluminescence process.
γ‐Irradiation Effect on the Thermal Conductivity of Al2O3 with Cr or Mn Impurities at Low Temperature
Authors: de Goer A. M. , Dreyfus B.
Published: July 2007

The effect of γ‐irradiation on the thermal conductivity of samples of Mn or Cr‐doped Al2O3 is measured between 1.3 and 300 °K. Ions with an even number of electrons (particularly those with the Mn3+ configuration) are much more effective in scattering phonons than Kramers' ions. Comparison of the experimental data therefore strongly suggests the presence of Cr2+, isoelectronic of Mn3+, in irradiated ruby. A preliminary study of the thermal annealing shows that the recovery of the thermal conductivity is rather complicated.
Zur Versetzungsanordnung in dünnen, durch Kristallisation gewonnenen Germanium‐Folien
Authors: Paschoff N. , Heydenreich J.
Published: July 2007

Durch Kristallisation aus der Schmelze hergestellte dünne Germanium‐Folien werden elektronenmikroskopisch in Durchstrahlung untersucht. Typisch für die ‐ meistens in 〈111〉‐Orientierung vorliegenden ‐ Folienbereiche ist das Vorhandensein relativ geradlinig in 〈112〉‐Richtung verlaufenden 30°‐Versetzungen und in 〈110〉‐Richtung liegender 60°‐Versetzungen. Eine Modellvorstellung für die Entstehung einer aus parallelen, in 〈112〉‐Richtung verlaufenden Versetzungen bestehenden Versetzungsanordnung wird vorgeschlagen. Einige Beispiele für die Wechselwirkung von Versetzungen auf der Grundlage eines „super kink”︁‐Modells werden hervorgehoben.
Dielectric Properties of Interstitial Impurity Cations in Alkali Halide Crystals
Authors: Lal K.
Published: July 2007

The dielectric behaviour of an interstitial divalent impurity cation associated with cation vacancies in alkali halide crystals is investigated. Two cases are considered: In the first case the two cation vacancies are assumed to be at the nearest neighbour positions. In the second case the impurity is assumed to be attached to one vacancy at a second nearest neighbour position. The impurity‐vacancy dipoles show relaxational losses, which reach a maximum at 4 ω1 in the first case and at ω1 in the second case. Here ω1, is the jump frequency of the vacancy between lattice sites. The maximum values of the loss tangent are calculated for the two cases and compared with that obtained for the case of a substitutional impurity associated with one vacancy at a nearest neighbour position.
Investigation of the Thermal Conductivity of InSb‐GaSb Solid Solutions
Authors: Zeinalov S. A. , Aliev M. I.
Published: July 2007

Results of a thermal conductivity study on InSb‐GaSb solid solutions are presented for the entire solubility range of 80 to 500 °K. It is shown that the thermal conductivity is mainly due to the lattice. Up to a certain temperature three‐phonon processes are prevalent in all the solid solution samples. In alloys near the equimolar composition the lattice thermal resistance does not depend on T. This is due to the limitation of the phonon mean free path by the random structure of the alloy and by heat transfer through the quantum exchange of energy between the neighbouring atoms of the lattice.
Luminescence and Photoconductivity of the B‐Centre in Additively Coloured KCl:Ag Crystals
Authors: Degrieck W. , Jacobs G.
Published: July 2007

The luminescent and photoconductive properties of the complex B‐band in additively coloured KCl: Ag are investigated in the temperature range between 300 °K and liquid helium temperature. A mechanism is proposed to account for the absence of low temperature fluorescence and the parallel occurrence of photoconductivity and luminescence at higher temperatures. The experimental data are discussed on the basis of a configuration coordinate diagram.