bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hall Effect in Single Crystals of Magnesium
Authors: Alty J. L. , Stringer J. 
Published: July 2007

AbstractThe Hall effect has been measured in seven single crystals of high purity magnesium at room temperature. The results indicate that the two independent coefficients of the Hall tensor are equal, the metal behaving isotropically; R⊥ = R| = −(7.8 ± 0.8) × 10−11 m3 C−1. The single crystal values of the Hall coefficients for the hexagonal metals Mg, Zn, Cd, and Ti are tabulated; there is no simple relation between them and the axial ratio.
Bulk Quantum Efficiency in Indium Antimonide
Authors: la Guillaume C. Benott À , Fishman G. 
Published: July 2007

AbstractThe bulk quantum efficiency η of indium antimonide is studied between 4 and 300 °K with doping concentrations ranging from 2 × 1014 to 2 × 1018 donors cm−3. Using the formula η = τN/(τN + τR) (where τR is the radiative lifetime and τN the non‐radiative one), it is possible to deduce from the experimental results the importance of different non‐radiative processes since τR is relatively well‐known. It is shown that the Auger effect is predominant with regard to the recombination through the mechanism of trapping (Shockley‐Read process) at high temperatures or for high doping concentrations.
Luminescence de cristaux de tellurure de cadmium
Authors: Noblanmc J. P. , Loudette J. , Duraffourg G. 
Published: July 2007

AbstractNous avons étudié la photoluminescence et la cathodoluminescence du CdTe aux températures de l'azote, de l'hydrogène ou de l'hélium liquides entre 1,3 et 1,6 eV avant et après polissage chimique. Les monocristaux étudiés ne sont pas intentionnellement dopés, leur concentration en porteurs est déterminée par la pression partielle de cadmium pendant le recuit. Nous avons observé sur tous les échantillons une raie très large (0,1eV) située autour de 1,42 eV dont l'intensité est très sensible au polissage chimique et varie proportionellement à l'excitation. La comparaison de cette raie avec la raie „intrinsèque”︁ (≈ 1,58 eV à 78 °K), dont l'intensité est proportionnelle au carré de l'excitation, nous permet de conclure qu'elle est due à des défauts situés dans une couche de surface de profondeur inférieure à 1 μm. La raie „intrinsèque”︁ (1.594 et 1,58 eV à l'hydrogène et à l'azote liquide respectivement) présente sur le flanc haute énergie une structure à ces deux températures. L'application du principe de bilan détaillé permet d'obtenir la forme du coefficient d'absorption que nous comparons aux spectres de réflectivité: nous attribuons la raie principale à l'annihilation de l'exciton libre de l'état fondamental n = 1 dont nous évaluons l'énergie à (1,5838 ± 0,0007) eV à 78 °K, et à (1,5855 ± 0,0007) eV à 22 °K. La structure côté haute énergie est attribuée à l'annihilation de l'état n = 2 de l'exciton libre (1,591 eV à 78 °K) et à la transition bande à bande (1,595 eV à 78 °K).
Stage I Recovery of Deformed Platinum
Authors: Swanson M. L. , Quenneville A. F. 
Published: July 2007

AbstractThe stage I recovery (below 60 °K) of deformed 99.999% purity Pt has been investigated by residual electrical resistivity measurements. After extensions of 1 to 3% at 5 °K, recovery peaks were observed at (16 ± 1), (28 ± 1), and (36 ± 1) °K, with associated activation energies (0.05 ± 0.01), (0.073 ± 0.01), and (0.14 ± 0.01) eV. A prior deformation and 300 °K anneal not only increased the stage I recovery by a factor of two, but also enhanced its structure. The 16 °K substage was due to short range defect migration. The 28 °K substage was similar to that observed after electron irradiation of Pt, which is attributed to free interstitial migration. The main Frenkel pair annealing substages which are observed after fast particle irradiation were absent in deformed Pt.
Electron Population of Dislocation Levels in an Illuminated Covalent Semiconductor
Authors: Fortini A. 
Published: July 2007

AbstractThe occupation ratio of the acceptor levels associated with the dangling bonds of a dislocation in a covalent semiconductor submitted to optical electron‐hole generation is calculated thermodynamically. The same approach is also applied to the similar problem, first considered by Read, of an n‐doped semiconductor. Numerical calculations for germanium at different temperatures, assuming a dislocation level 0.2 eV below the conduction band edge, show that the occupation ratio increases as the temperature is decreased. At moderate temperatures, values as high as 0.1 can be reached by reasonable injection or impurity doping, the efficiency of both methods being roughly the same.
Aragonite Transformations Observed in the Electron Microscope
Authors: Burrage B. J. , Pitkethly D. R. 
Published: July 2007

AbstractIt is possible to observe the known transformations of aragonite to calcite to lime using an electron microscope. Aragonite undergoes a sudden and violent transformation when heated by the electron beam. Twins and dislocations disappear, leaving a strained crystal of aragonite of occasionally calcite. Further heating produces calcium oxide with a strongly preferred orientation relative to the carbonate.
Energy Band Structure of AIN
Authors: Hejda B. 
Published: July 2007

AbstractThe energy band structure of AIN is calculated by means of the orthogonalized plane wave method at the points Γ, A, K, H, M, and L of the Brillouin zone. 135 plane waves have been used at the point Γ. The results to Herman and Skillman who calculated them with the Slater approximation for the exchange potential have been used as atomic wave functions and potentials.
Eine MO‐theorie der Spin—Phonon‐Wechselwirkung
Authors: Böttger H. 
Published: July 2007

AbstractDie Spin—Phonon‐Wechselwirkung eines paramagnetischen Ions in einem Ionenkristall durch den Van Vleck‐Mechanismus wird in einem Modell untersucht, in dem das paramagnetische Ion und seine nächsten Nachbarn als Molekül betrachtet werden, dessen Zustände durch MO (molecular orbital)‐Funktionen beschrieben werden. Es wird ein Elektron‐Phonon‐Wechselwirkungsoperator aufgestellt, der neben Termen des üblichen Punktladungsmodells weitere durch Überlappung und Kovalenz bestimmte Terme enthält. Eine Abschätzung für das System Ni++ in MgO zeigt, daß der Einfluß der einiger dieser Terme auf die Spin—Phonon‐Wechselwirkung vergleichbar mit dem Einfluß der Terme des Punktladungsmodells sein kann.
Lattice Reflection and Optical Constants of ZnSnP2 Crystals with Chalcopyrite and Sphalerite Structure
Authors: Zlatkin L. B. , Markov J. F. , Stekhanov A. I. , Shur M. S. 
Published: July 2007

AbstractThe infra‐red reflectivity of ZnSnP2 has been investigated in the wavelength range 2 to 60μm at T = 295 °K. The optical constants and vibrational frequencies are determined; for the chalcopyrite structure they are ϵ∞ = 8.1 ± 0.2, ϵ0 = 10.0 ± 0.4, n = 2.84 ± 0.04, ωl 0 = 368 cm−1, ωt 0 = 330 cm−1; for the sphalerite structure they are ϵ∞ = 8.3 ± 0.2, ϵ0 = 10.8 ± 0.4, n = 2.88 ± 0.04, ωl 0 = 362 cm−1, ωt 0 = 318 cm−1. The effective ionic charge is estimated by the Szigeti formula. The values are for the chalcopyrite structure e*/e = 0.58, for the sphalerite structure e*/e = 0.63. The compressibility has been estimated to β × 1012 = 1.28 and 1.34 (cgs units) for the chalcopyrite and sphalerite structure, respectively, and the Blackman sum rule has been checked. The parameters of the dispersion oscillators have been obtained from dispersion analysis. The magnitude of the parameter γ characterizing the damping of the oscillator, γ = 0.061 (chalcopyrite structure) and γ = 0.110 (the sphalerite structure), exceeds the corresponding values for the compound GaP and InP; that is possibly due to stronger phonon‐phonon interaction in ZnSnP2. Using dispersion analysis and Kramers‐Kronig analysis the disperison of the refractive index and the dielectric constant due to the lattice vibrations has been calculated.
Electric Properties of Dislocations in p‐Type Germanium
Authors: Kryłow J. 
Published: July 2007

AbstractThe aim of the present paper is an explanation of the decrease in the carrier concentration found in p‐type germanium after deformation. The investigation shows that the observed effect is not necessarily connected with the donor action of dislocations and that it can also be caused by the precipitation of acceptors on dislocations. If we assume a donor action of dislocations then the donor level lies about 0.22 eV above the top of the valence band.
Resistance Minima in Nondilute CeLa and CeY Alloys
Authors: Elliott R. O. , Hill H. H. , Miner W. N. 
Published: July 2007

AbstractMinima that may be indicative of a spin‐compensated magnetic state have been observed in the electrical resistivity data for certain nondilute, hexagonal CeLa and CeY alloys. Resistively‐determined Néel temperatures do not agree with those determined magnetically for CeLa alloys containing ⪆ 21 at% La.
Research of the Anisotropic Potential in Eu2(WO4)3 Single Crystals with 3 eV Samarium Recoil Atoms by Means of Nuclear Resonance Fluorescence
Authors: Abel F. , Kalus J. 
Published: July 2007

AbstractThe slowing‐down behaviour of 3 eV Sm152 recoil nuclei which are created by the neutrino emission from Eu152m was studied in a single crystal of Eu2(WO4)3 with the help of nuclear resonance fluorescence (NRF). The expected dependence of the NRF yield on the flight direction of the Sm nuclei in the anisotropic crystal potential was observed. The twofold rotational symmetry of the b0‐axis and the angle β of the monoclinic crystal reproduced themselves in the experimental results. The maximum variation of the NRF yield was (3.9 ± 0.1)%. — The model which uses a nonspherically symmetric parabolic potential

permitted the calculation of the theoretical NRF yield. The arbitrary parameter occurring in the model was determined by comparison with the experiment.
Quadrupole Broadening of Nuclear Magnetic Resonance Lines in Deformed Copper and Aluminum
Authors: Kanert O. 
Published: July 2007

AbstractThe nuclear magnetic resonance lines of Cu63 and Al27 in bulk polycrystalline copper and aluminum have been measured as a function of plastic deformation. The line shape of these signals shows a quadrupolar broadening from which the mean dislocation density of the deformed samples may be determined. It was found that in each the flow stress which is effective during the deformation is proportional to the square root of the dislocation density. — The NMR signal of a plastically deformed copper single crystal shows a dependence of the quadrupole perturbation on the direction of the external magnetic field H0 relative to the crystal axes. This results can be explained on the basis of the special position of the dislocations in the lattice.
Electronic Displacement in Tellurium by Mechanical Strain
Authors: Arlt G. , Quadflieg P. 
Published: July 2007

AbstractThe piezoelectric constants e11 and e14 of tellurium have been found by measurement to be 0.42 C m−2 and 0.17 C m−2. They are described by strain‐induced displacement of the electron distribution relative to the Te cores.
ESR Study of Paramagnetic Centres Formed by Introduction of Ca2+ in NaCl and NaBr Single Crystals
Authors: Nicula Al. , Fârcaş S. I. , Darabant Al. 
Published: July 2007

AbstractThe defects formed by introduction of Ca2+ ions in NaCl and NaBr single crystals and after UV irradiation at room temperature have been observed by the electron spin resonance method. Two types of paramagnetic centres have been detected: one with axial symmetry and the other with orthorhombic symmetry. The highly anisotropic g‐factor of these centres proves that the responsible electron for the observed absorption is not in an s state. The formed centres decay at approximate 400 °K.
Errors in the Numerical Calculation of the Moments of the ESR Absorption Curves
Authors: Buluggiu E. , Dall'olio A. , Varacca V. 
Published: July 2007

AbstractWhen calculating the moments of the ESR absorption curves from the derivatives with the usual numerical integration method of the odd moments, an error is made due to the fact that one neglects a term with respect to the analytical integral. In the present work, we show that this error is remarkable for the second moments of a cut‐off Lorentzian curve and decreases the more the line shape approaches a Gaussian shape.
Structural and Electrical Properties of Solid Polymeric Carbon Disulphide
Authors: Chan W. S. , Jonscher A. K. 
Published: July 2007

AbstractIt is known that liquid CS2 when subjected to high pressure forms a stable solid polymer. Our studies revealed the existence of two distinct forms designated here A and B. Chemical evidence suggests that type A has the composition CS2 and contains no free sulphur, while type B does contain free sulphur and may be a sub‐sulphide. Infrared structural studies suggest that type A has a highly conjugated polymeric chain structure. X‐ray evidence suggests absence of long range order in both the A and B materials. The dc resistivity of type A is about 1013 Ωcm at 300 °K with an activation energy of 0.7 eV and that of type B is about 103 Ωcm with about 0.02 eV activation energy. The resistivity of both is strongly pressure dependent. Both types show strong frequency dependence of conductivity and permittivity with a region of σ ∼ f2 at high frequencies and saturating at 109 and 1010 Hz, respectively. Although it is impossible to prove that the observed ac data are not related to some form of Maxwell‐Wagner mechanism, it is pointed out that, at least in the case of the A material, the pressure, frequency, and temperature dependences of resistivity are more likely to be associated with two processes in which partially localized electrons hop within chains at high frequencies and between chains at lower frequencies.
Decoration of Strain Bands with F‐Centres in Potassium Chloride Crystals Deformed by Indentation
Authors: Damm J. Z. , Suszyńska M. 
Published: July 2007

AbstractIt is shown that the strain bands introduced into potassium chloride crystals by an indentor can be decorated with F‐centres in a simple procedure involving coloration by ionizing radiation and optical bleaching. The method reveals the existence of strain bands distributed along 〈110〉, 〈111〉, and 〈120〉 directions. On assuming that the macroscopic accumulations of vacancies responsible for the above effect are due to dislocations intersecting each other the formation of 〈120〉 bands necessitates the operation of {112} 〈110〉 or {122} 〈110〉 glide systems in which the screw dislocations are moving.
Investigations of Photoelectric Phenomena on p‐type Germanium with Dislocations
Authors: Jastrzębska M. , Figielski T. 
Published: July 2007

AbstractSteady state and transient photoconductivity are investigated in plastically bent p‐type Ge. At low temperatures a trapping effect is observed. All characteristics of photoconductivity are qualitatively the same as for plastically deformed n‐type Ge in which recombination occurs through dislocations. The experimental results are explained on the basis of a barrier model of recombination at dislocations assuming that in p‐type Ge a dislocation which gives up the unpaired electrons to the valence band becomes positively charged. It is found (from experiment) that the dislocation donor level lies (0.28 ± 0.02) eV above the top of the valence band at 0 °K. The comparison with previous results obtained for n‐type Ge shows that the location of the donor as well as of the acceptor dislocation level is approximately the same in the energy gap. This result is consistent with the assumption that the states connected with the broken bonds at dislocation form an one‐dimensional energy band.
Strain Aging of Niobium in the Temperature Range 100 to 200 °C
Authors: Soo P. 
Published: July 2007

AbstractStrain aging experiments have been conducted on polycrystalline niobium, containing approximately 100 ppm by weight of interstitial impurities. For aging temperatures in the so‐called stage III recovery region, which lies between 100 to 200 °C, recovery occurs in two separate and independent substages. The first substage is thought to be caused by the detrapping of self‐interstitials which are then able to migrate through the lattice and form new defect configurations. The second substage is probably connected with the migration of oxygen interstitials. The study indicates that the pinning of dislocations may also occur during the recovery and, under suitable conditions, dislocations may be successively pinned by self‐interstitials, oxygen interstitials, and carbon (or nitrogen) interstitials.
Electron and Neutron Damage in MgF2 Crystals
Authors: Facey O. E. , Lewis D. L. , Sibley W. A. 
Published: July 2007

AbstractA comparison of electron‐ and neutron‐radiation damage in MgF2 single crystals has been made by studying changes in the optical absorption. It is found that reactor irradiation introduces many more cluster centers than does electron irradiation. Annealing studies show that above 700 °K F‐centers are apparently mobile and aggregate to form M‐centers. Zero phonon and phonon‐assisted lines are observed at 382.6, 384.5, 385.7, and 387.3 nm and have been shown to be associated with the broad absorption band at 370 nm which is due to M‐centers.
X‐Ray Diffraction Topography of Zinc Single Crystals
Authors: Nanev Chr. , Wilkens M. 
Published: July 2007

AbstractCrystal imperfections in zinc single crystals were studied by X‐ray topography. The zinc single crystals were obtained in a glass ampule from a molten droplet which, after solidification, acted as a nucleus for further growth from the vapour phase. The crystals adhered strongly to the glass support. The X‐ray topographs give informations on the modes of plastic deformation, which occurred in the crystals during cooling. The existence of dislocations with Burgers vectors of type 1/3 〈1123〉 is demonstrated. This agrees well with the observed whisker growth in these directions. Some other phenomena connected with the crystal growth are also discussed.
Non‐Equilibrium Surface Space Charge in Semiconductors for Arbitrary Ionization Degree of Impurities
Authors: Dmitruk N. L. 
Published: July 2007

AbstractThe theory of the surface space charge region has been generalized to the case of non‐equilibrium conditions and arbitrary occupation of local centres within the band gap. The contribution of different local levels to the non‐equilibrium surface charge has been analysed in detail. Non‐equilibrium surface effects (capacitance, field‐effect, barrier photovoltage) are calculated for the model considered which is often realized at low temperatures and in broad band gap semiconductors (GaAs, CdS etc.).
High Temperature Expansions of Spin Correlation Functions for Ising and Heisenberg Ferromagnets
Authors: Binder K. 
Published: July 2007

AbstractLinked cluster expansions are given for the static spin pair correlation functions in the case of Ising and Heisenberg interactions. Formulae valid for general values S of the spin are derived including terms of fifth order in 1/(kT). These expansions are discussed numerically in the temperature region Tc/T ≦ 1/2 for the simple cubic, the body‐centered cubic and the face‐centered cubic lattice assuming interactions between nearest neighbours only. A comparison with the usual Ornstein‐Zernike treatments shows considerable deviations due to the anisotropy of the correlations. This anisotropy can be neglected only in the immediate neighbourhood of the critical temperature Tc.
Rare Gas Diffusion in Alkaline‐Earth Fluorides (Kr, Xe in SrF2, BaF2)
Authors: Felix F. W. , Lagerwall S. Y. T. 
Published: July 2007

AbstractThe diffusion of Kr and Xe in SrF2 and BaF2 has been studied after reactor neutron irradiation using both pure single crystals and single crystals doped with uranium. The activation energies for migration of Kr and Xe in SrF2 are 1.2 and 3.7 eV, in BaF2 1.5 and 3.5 eV, respectively. The results are discussed and compared with results on CaF2.
Anisotropic Spin–Orbit Coupling for Cr3+ in ZnWO4
Authors: Hagston W. E. 
Published: July 2007

AbstractThe anisotropic orbital effects produced by admixture of ligand wave‐functions into 3d‐orbitals is shown to account for the apparent incompatibility of the results of optical and e.p.r. results for Cr3+ in ZnWO4.
The Effective Field and the Differential Susceptibility in Ferromagnetic Films
Authors: Hoffmann H. 
Published: July 2007

AbstractA theory of the differential susceptibility is given for two‐dimensional ferromagnetic samples. The susceptibility depends on the intrinsic demagnetizing field which is caused by the magnetization inhomogeneities. The susceptibility is related to the mean “effective field” as well as to the magnetization fluctuation. Its measurement can be used to determine quantitatively these properties which are related to the structure constant, S. The latter results from the inhomogeneity of the anisotropy.
On the Mathematical Description of Electrical Processes in Semiconductors. II. Phase Space Analysis in Subspaces of Dimension Three
Authors: Oberländer S. 
Published: July 2007

AbstractIn Part I of this paper classes of systems of solutions without approximation, so‐called N‐dimensional systems of solutions, have been given for N < 3 for the system of differential equations consisting of the continuity equations with a recombination law based upon the law of mass action, the common current equations, and Poisson's equation. In the present Part II systems of solutions for N = 3 are given. Applications to stationary problems of transport of non‐equilibrium carriers in semiconductors are discussed. Especially an interesting example with a non‐monotonous hole concentration in a semi‐infinite homogeneous semiconductor is treated. An approximation method for three‐dimensional systems of solutions is shown for the example of the so‐called anti‐neutrality approximation.
Ionic Conductivity of Crystalline CsBr
Authors: Chadwick A. V. , McNicol B. D. , Allnatt A. R. 
Published: July 2007

AbstractThe electrical conductivity of pure CsBr was measured between 295 and 895°K and the results analysed by least squares. Schottky disorder provides an adequate description of the results for the intrinsic conductivity except at the highest temperatures. The predicted diffusion coefficients are compared with the experimental values of Lynch [1].
Point de Curie de KDP avec et sans effet tunnel
Authors: Villain J. , Aubry S. 
Published: July 2007

AbstractNous étudions la thermodynamique de KDP en ne considérant que les interactions entre les spins fictifs associés aux protons premiers voisins dans des modèls plans et spatiaux. On montre d'abord qu'on découple complètement le mouvement des spins fictifs du mouvement des ions en définissant une nouvelle énergie d'interaction entre les premiers et en renormalisant les seconds. On étudie ensuite l'effet tunnel entre protons formant un cycle fermé, en regardant successivement son influence sur les états à une et deux excitations élémentaires. Ceci permet de penser qu'une transition du 2ème ordre n'est pas exclue. Nous notons enfin que ce modèle conduit à un mode mou correspondant à une diffusion de spins fictifs et non à un phonon optique.
X‐Ray Diffraction by a Crystal Containing a Translation Fault
Authors: Bonse U. , Hart M. 
Published: July 2007

AbstractWe consider the diffraction of X‐rays by a bicrystal consisting of a thick part and a thin part separated by a rigid body translation. Both parts have identical lattice parameters. This simple model and the plane‐wave diffraction theory developed herein describe very well the contrast and geometry of the fringes obtained in X‐ray diffraction topographs of some silicon crystals bombarded by monoenergetic ions.