bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of the Dislocation Dipole in Half‐Space
Authors: Bacon D. J. 
Published: July 2007

AbstractThe stability of an edge dislocation dipole of infinite length lying parallel to the free surface of an isotropic, semi‐infinite medium has been investigated by determining the dipole orientation for which the stress on both poles is less than a chosen dislocation friction stress. It is found that the effects of the surface are considerable, despite the fact that the stress field of the dipole is short‐ranged. In particular, the surface can induce orientations of stability which are not expected from the infinite body behaviour. Similar results are likely to arise for prismatic dislocation loops in bounded media. Some aspects of the effect of an applied shear stress on the dipole are also studied.
Anisotropy of High‐Field Helicon Propagation in PbTe
Authors: Schilz W. 
Published: July 2007

AbstractThe anisotropy of the helicon propagation in PbTe has been investigated theoretically using the anisotropic magneto‐conductivity tensor for static magnetic fields directed along the [100] and [110] axes of the crystal, the wave vector being rotated in a [110] plane. Experiments have been performed with flat samples of p‐ and n‐type PbTe single crystals. In the experiments, the wave vector was directed along the [100], [110], and [111] axes of the crystal. A marked dependence of the resonance frequency and the Q‐value of the helicons on the direction of the wave vector with respect to the magnetic field direction and the crystal axes has been observed.
Hyperfine and Quadrupole Interactions of the F‐Centre in KCl as Measured by ENDOR
Authors: Kersten R. 
Published: July 2007

AbstractThe isotropic and anisotropic hyperfine constants of the nuclei surrounding the F‐centre in KCl were newly determined by electron nuclear double resonance (ENDOR) in a region within the distance of three lattice constants around the centre (up to nuclei 003). Quadrupole interactions of nuclei 002, 102, and 112 could be measured.
PEM Effect with Short‐Circuited Dember Voltage
Authors: Pfleiderer H. 
Published: July 2007

AbstractShort‐circuiting of the Dember voltage affects the PEM effect. This is shown by simple phenomenological considerations. Under certain conditions, especially when the recombination due to the contact surfaces is not too strong, the application of Dember short circuits may increase the PEM effect. This is demonstrated by calculated values for intrinsic samples of InSb at room temperature.
Low‐Temperature Elastic Constants and Specific Heats of F.C.C. Nickel–Iron Alloys
Authors: Bower D. I. , Claridge E. , Tsong I. S. T. 
Published: July 2007

AbstractThe elastic constants of some single crystal specimens of nickel and f.c.c. nickel‐iron alloys have been measured at 4.2 °K and used to calculate values of the Debye temperatures. It is shown that by using these to re‐analyse some earlier specific heat measurements values of the spin‐wave contributions to the specific heats are obtained that are in good agreement with estimates made on the basis of small‐angle neutron scattering measurements of the exchange stiffnesses.
Contrast Asymmetries in Lang Topographs of Crystals Strained by Thin Films
Authors: Meieran E. S. , Blech I. A. 
Published: July 2007

AbstractCauses of contrast asymmetries between (h k l) and (h k l) Lang topographs of crystals strained by thin films are discussed. The images of film edges are approximated by direct and dynamical components, and experimental separation of these components is illustrated. The direct component, dominant for low μ t, is identical in (h k l) and (h k l) topographs, while the dynamical component, dominant for larger μ t, is asymmetrical and is responsible for the Lang topograph asymmetries. The asymmetries are due to the anomalous absorption or Borrmann effect, where waves belonging to one branch of the dispersion surface undergo less than normal absorption, while waves belonging to the other branch undergo more than normal absorption. It is shown that the absorption properties of these two branches can be reversed by suitable reflections from some crystals, leading to image asymmetry reversal.
The Study of Slip Bands on the Surface of Mo Single Crystals
Authors: Veselý D. 
Published: July 2007

AbstractSingle crystals of molybdenum, with the orientation of the tensile axis in the middle of the stereographic triangle, were deformed at 293 and at 400 °K, to different degrees of plastic deformation at a strain rate ε = 6 × 10−5s−1. The slip bands on the cylindrical surface of the crystals were studied by optical microscopy. At room temperature, at the beginning of deformation, a large number of slip systems with all four Burgers vectors are found to be operative. It is found that the slip planes do not correspond to those with maximum resolved shear stress, but rather to planes perpendicular to the surface. The slip bands belonging to the planes with maximum resolved shear stress are more pronounced, when the temperature and flow stress are increased; at 400 °K, in the region I, the primary slip system is dominant. These observations are explained assuming that screw dislocations have a low mobility, which can change under the influence of temperature and stress.
High Resolution Study of Crystal Field Lines in the Far Infra‐Red
Authors: Howell R. G. , Newman D. J. 
Published: July 2007

AbstractWe report the use of high resolution Fourier transform spectroscopy in the far infra‐red to study the lowest crystal field transitions in praseodymium ethyl sulphate and the double magnesium nitrates of cerium, praseodymium, neodymium, and samarium. The spectrometer employed is a Grubb Parsons Michelson interferometer with a Putley‐type indium antimonide detector at 2 °K. The observed line positions, intensities, and strengths are discussed in terms of conventional theories.
Phonon‐Assisted Exciton Transitions in AIIBVI Semiconductors
Authors: Dillinger J. , Koňák Č. , Prosser V. , Sak J. , Zvára M. 
Published: July 2007

AbstractIn CdS, CdSe, and CdTe investigations of both reflectivity – by polarimetric methods – and transmission are made in the spectral region of energies higher than the exciton ground state. An additional structure at energies of approximate Eex + ELO is explained by indirect exciton transitions with phonon emission and compared with simple second‐order perturbation theory taking into account ground exciton states only. The observed shift towards lower energies can be ascribed to the configuration interaction.
Die kritische Schubspannung mit zweiwertigen Kationen dotierter Alkalihalogenide II. Fremdion‐Leerstellen‐Dipol‐Agglomerate und fremdionenreiche Ausscheidungen
Authors: Frank W. 
Published: July 2007

AbstractBei Alkalihalogeniden, welchen genügende Mengen zweiwertiger Kationen zugesetzt sind, führt hinreichend langsames Abkühlen zur Ausscheidung fremdionenreicher Partikel. Sind die Ausscheidungen klein, so stellen sie Agglomerate von Fremdion‐Kationleerstellen‐Paaren dar. Es wird gezeigt, daß die kritische Schubspannung τ0 solcher Proben dadurch bestimmt ist, daß diese Partikel die Versetzungsbewegung behindern. Aus der Temperaturabhängigkeit von τ0 sowie aus seiner Abhängigkeit vom Fremdionengehalt werden quantitative Schlüsse über die mittlere Zahl zweiwertiger Kationen pro Ausscheidung gezogen. Es stellt sich heraus, daß die kleinsten Agglomerate drei Fremdion‐Kationleerstellen‐Paare enthalten. Lediglich in NaCl:Ca2+ treten auch Doppelpaare auf. Andererseits enthalten die Ausscheidungen in langsam abgekühltem LiF:Mg2+ einige hundert Mg2+‐Ionen. Die Untersuchungen dieser Arbeit erlauben eine qualitative Deutung der Abschreckver‐ und ‐entfestigung, welche bei mit zweiwertigen Kationen dotierten Alkalihalogeniden auftreten.
The Measurement of the Anisotropy Constant of Antiferromagnetic FePO4 by Means of the Mössbauer Effect
Authors: Beckmann V. , Bruckner W. , Fuchs W. , Ritter G. , Wegener H. 
Published: July 2007

AbstractIn a uniaxial antiferromagnet the anisotropy energy −K (cos2 ϑa + cos2 ϑb)/2 forces the atomic spins in the magnetic sublattices a and b parallel (K > 0) or perpendicular (K < 0) to the symmetry axis. An external magnetic field changes the spin directions. For iron atoms this spin rotation can be detected by means of the Mössbauer effect of 57Fe. The intensities of the six hyperfine structure lines depend on the direction of the internal magnetic fields, which are parallel to the atomic spins. Therefore a spin rotation causes a change of the line intensities. Further, in the presence of an electric field gradient at the iron nucleus the spin rotation affects the electric quadrupole shift in a way, which depends on the sign of K. We have investigated a polycrystalline probe of calcined FePO4. The substance is antiferromagnetically ordered below 25 °K. At 4.2 °K we obtained K = = +(4.6 ± 0.5) × 105 erg/cm3.
Energy Band Structure of ZnxHg1−xTe Solid Solutions
Authors: Dziuba E. Z. , Niculescu D. , Niculescu N. 
Published: July 2007

AbstractFrom electrical and optical data, the energy gap versus composition for ZnxHg1−xTe system is given. The deviation from the linearity is explained as an effect of the change of the covalent radii of the Zn, Hg, and Te atoms.
Magnetic Properties of Some Co‐Rich Erbium Cobalt Intermetallic Compounds
Authors: Buschow K. H. J. , Fast J. F. , van der Goot A. S. 
Published: July 2007

AbstractThe magnetization for the ferrimagnetic compounds Er2Co17, ErCo6, and Er2Co7 has been studied in the temperature range 4.2 to 1250 °K and at field strengths up to 30 kOe. The Curie temperatures and the saturation magnetizations at 4.2 °K have been determined. For all compounds a maximum has been observed in the magnetization versus temperature curves. Er2Co7 shows a compensation point at 140 °K. For this compound changes in the crystalline anisotropy were observed near the compensation point. The values of the coercive force obtained by mortar grinding samples of Er2Co17, ErCo6, Er2Co7, and ErCo3 are compared with the variation of the lattice parameters for these compounds.
Temperature Dependence of Hyperfine Interactions in Near‐Stoichiometric FeS I. Experiment
Authors: Thiel R. C. , van den Berg C. B. 
Published: July 2007

AbstractMössbauer measurements as a function of temperature are presented for three synthetic 57Fe‐enriched polycrystalline samples of FeS in the composition region near stoichiometry. The independence of the Morin and α‐transitions, previously concluded from neutron diffraction measurements, has been verified. A low‐temperature transition has been found near 200 °K. It appears necessary to postulate the existence of a reversible, crystallographic two‐phase region between the α‐transition and about 200 °K in order to explain the Mössbauer measurements. This hypothesis also seems to provide a logical explanation of several anomalies in FeS.
Fault Structures in Ti2O
Authors: Jostsons A. , McDougall P. G. 
Published: July 2007

AbstractThe structure of Ti2O can be described in terms of a hexagonal close packed arrangement of titanium atoms (c/a = 1.637) in which oxygen atoms are ordered so that they occupy every second layer of octahedral interstices normal to the c‐axis. The nature of possible antiphase domain boundaries and stacking faults in this ordered structure is discussed and compared with transmission electron microscope observations of fault boundaries. – Direct evidence is presented showing that cast specimens, which are ordered at room temperature, contain a high density of growth faults (1 (Δ) faults) at which neighbouring (0001) planes of octahedral interstices are either both occupied by oxygen atoms or both vacant. The (0001) faults are eliminated by high temperature annealing which gives rise to an antiphase domain structure with a morphology of the „Swiss‐cheese”︁ type. The antiphase vector is (c/2 + Δc) [0001] where Δc is a term indicating the presence of lattice strains parallel to [0001] direction at the antiphase boundary. – From the microstructural changes it is concluded that Ti2O solidifies as a disordered c.p.h. structure containing a high density of low energy growth faults which are modified by oxygen ordering during cooling to room temperature.
Perfect Dislocations in the Wurtzite Lattice
Authors: Osipiyan Yu. A. , Smirnova I. S. 
Published: July 2007

AbstractA detailed analysis has been made of hypothetically possible types of perfect dislocations in the wurtzite structure. A possible electrical activity of the dislocations, depending on the number of broken bonds and atomic polarity of the core is discussed and possible dislocation reactions are pointed out. The energetic balance of the reactions is estimated considering only the change of their elastic energy, determined by squares of their Burgers vectors.
Anharmonic Broadening of Resonant Modes
Authors: Timmesfeld K. H. 
Published: July 2007

AbstractIn order to describe the strong temperature dependence of the infrared absorption of Cu+ in NaCI a model is investigated in which the Cu+ is coupled to its nearest neighbours by harmonic and cubic anharmonic forces. The problem is solved by means of retarded Green's functions solving a Dyson equation with a mass operator of second order in the cubic anharmonicity. The pure crystal is described by a Debye model because the impurity‐induced absorption takes place in the very far infrared (ωR ≈ 1/10 Debye frequency). By iterating the mass operator a good agreement between theory and experiment is reached.
Heat Capacity and Quasi‐Chain Dynamics of Diamond‐Like Structures
Authors: Tarassov V. V. , Demidenko A. F. 
Published: July 2007

AbstractThe heat capacities of a number of semiconducting substances (Si, GaAs, GaP, etc.) have been calculated on the basis of the quasi‐chain dynamics of covalent crystals [9]. It is shown that the characteristic frequencies v3 and v1 correspond to the respective dispersion frequencies at the points Γ(0, 0, 0), X(1, 0, 0), and L(0.5, 0.5, 0.5) of the Brillouin zone determined from the inelastic scattering of slow neutrons, and that it is possible to calculate the parameters ϑ1 and ϑ3 from the data of multi‐phonon absorption. The heat capacities of GaP, measured in the range 55 to 300°K, are given.
Determination of the Average Number of Replacement Collisions in an Electron‐Irradiated F.C.C. Crystal (Ni3Mn)
Authors: Becker D. , Dworschak F. , Lehmann C. , Rie K. T. , Schuster H. , Wollenberger H. , Wurm J. 
Published: July 2007

AbstractThe electrical resistivity and saturation magnetization damage rates in ordered Ni3Mn and in pure Ni have been measured during 1.0 and 3.0 MeV electron irradiation at low temperatures. The effect of Frenkel pairs on the damage rates is assumed to be equal in Ni and in Ni3Mn; thus, the difference between the damage rates merely yields the disordering effect caused by replacement collisions. Changes of the long range order parameter S then were determined using empirical expressions relating the electrical resistivity and the saturation magnetization to S. Consideration of the relationship between S and the number of replacement collisions in 〈110〉 rows yields an average number of (2.2 ± 2.2) replacements per Frenkel pair. This result is discussed in view of experimental recombination volumes and computer experiments.
Impurity Diffusion in Face‐Centred Cubic Metals
Authors: Naik M. C. , Anand M. S. , Paul A. R. , Agarwala R. P. 
Published: July 2007

AbstractAn attempt has been made to correlate the Gibbs free energy of the self and impurity diffusion in f.c.c. metals (Ag, Cu, Au, Ni, Pb, and Al) with some of their physical parameters (like atomic radius r, melting temperature T of the solute, and compressibilities k′ and k of the solute and the solvent) along with the electrostatic interaction (βZ) of the solute and the solvent. A linear relationship of the form ΔG = A + B (Tr/(k′ + 2k)) − βZ could be obtained with constants A and B, characteristic of each of the solvents.
Formation of Radiation Defects by Channeling Particles
Authors: Kumakhov M. A. 
Published: July 2007

AbstractThe problem of interaction of channeling ions with chain nuclei forming the channel is considered. Born‐Mayer potentials for CuCu, Moliere, Firsov, and Lindhard potentials are considered as interaction potentials. The energy transferred to the chain nuclei is estimated. In some cases this energy may exceed the threshold energy of atomic displacement. The light channeling ions do not produce displacements. The problem of the influence of the channeling effect on the radiation cascade is also considered. It is shown that this influence is insignificant except for the cases when the initially displaced atoms have high energies.
Peculiarities of the Energy Spectrum and Edge Absorption in the Chain Compounds AVBVICVII
Authors: Chepur D. V. , Bercha D. M. , Turyanitsa I. D. , Slivka V. Yu. 
Published: July 2007

AbstractSome band structure peculiarities of AVBVICVII compounds have been investigated by methods of group theory, the interaction between the chains being taken into account. Experiments show that the peculiarities occur on both spectra of the crystals BiSeI, the absorption edge and the photoconductivity. The results obtained are explained by band structure peculiarities.
ESR Studies of Cupric Ion in Various Oxide Glasses
Authors: Imagawa H. 
Published: July 2007

AbstractESR spectra of cupric ions in borate, silicate, and phosphate glasses were analyzed by the LCAO MO method of Maki and McGarvey. The covalency of the B2g π‐orbital was found to change with the bond strength of the network‐former. Particularly it reflected clearly the weakening of BO bonds in alkali borate glasses with increasing alkali content or with increasing ratio of BO4 tetrahedra to BO3 triangles. Microscopic fluctuations in glass were found essential to explain the line shape of the hyperfine structure. Two different states of cupric ions were observed in some quenched glasses.
Shell Model Treatment of the Vibrations of Crystals Containing Substitutional Defects. II. On the Theory of Defect‐Induced One‐Phonon Absorption
Authors: Strauch D. 
Published: July 2007

AbstractA formalism for defect‐induced one‐phonon absorption in the harmonic approximation is presented. The influence of charge changes of defects on the crystal dipole moment is twofold: the charges themselves as well as their displacements are perturbed by these changes. Averaging over defect configurations energy shift and width of plane‐wave‐like phonons is obtained. A self‐consistent solution of the perturbed Green's function which takes into account perturbations up to second order in the defect concentration is used. In the homopolar crystals absorption occurs only if the actual (not effective) charges are changed. Comments are made on effective charges and their changes.
A Contribution to the Calculation of Magnetization Curves and Minor Loops
Authors: Heinecke U. 
Published: July 2007

AbstractThe model of an anisotropic permanent magnet is imitated on a digital computer and the demagnetization curve and the family of minor loops are calculated. The approximations of this method are: rectangular loops of the elementary magnets and the location of these particles at lattice points. The values of the magnetic interaction field intensity are evaluated from experimentally determined parameters of a real magnet sample. The calculated loops agree in most of the characteristics with the experimental curves. Deviations may be reduced by a suitable correction of the distribution curve of the critical field values of the particles.
Transport Properties of Silver Telluride in the Solid and Liquid States
Authors: van Dong Nguyen , Tung Pham Ngu 
Published: July 2007

AbstractMeasurements of the electrical resistivity, Hall coefficient, and thermoelectric power have been carried out for silver telluride over a large temperature range including both solid and liquid states. The analysis of the experimental data shows that in the solid state the transport properties are governed by an ambipolar process with an electron mobility much higher than the hole mobility (μn = 10 μp). It is found that the temperatur dependence of the electron mobility can be represented by a T−3‐law. Deviations from the stoichimetric composition of Ag2Te have been studied. For all specimens, melting is accompanied by discontinuous variations in the transport propeties. Above the melting point, the magnitude of the measured parameters and their temperature dependence show that liquid silver telluride behaves as a semiconductor. The contribution of Ag+ ions to transport phenomena is suggested to account for the behaviour of the electrical properties. Experimental data have been analysed in terms of conventional theories.
Observation of Quantum Galvanomagnetic Phenomena in n‐Type Indium Antimonide
Authors: Huff H. R. , Kawaji S. , Gatos H. C. 
Published: July 2007

AbstractQuantization effects in the bulk galvanomagnetic properties of n‐type InSb were studied in conjucntion with the transport properties of compound semiconductor surfaces. The transverse and longitudinal magneto‐resistivity were measured at 4.2, 50, and 77°K. The former was found to increase with increasing magnetic field at all temperatures and (for a given temperature) was an order of magnitude larger than the latter which became saturated at the two higher temperatures. At 4.2°K, the electrons were weakly degenerate and the bulk mobility was determined by ionized impurity scattering. At 77°K, the electrons were non‐degenerate and the predominant scattering mechanism was probably high‐temperature optical phonon scattering.
Die Berücksichtigung der Austauschwechselwirkung im Zweiteilchenbild der Exzitonen und ihr Einfluß auf die Exzitonenspektren
Authors: Dos K. , Haug A. , Rohner P. 
Published: July 2007

AbstractDie Berücksichtigung der Austauschwechselwirkung der Electronen liefert einen zusätzlichen Term in der Zweiteilchengleichung für Exzitonen, der zu einer wesentlichen Modifizierung der Exzitonenspektren führt. Dadurch können sowohl die Nullfeldaufspaltung der Exzitonenlinien als auch Abweichungen von der Wasserstoffähnlichkeit der Spektren gedeutet werden.
The Ordering of Ni3V
Authors: Tanner L. E. 
Published: July 2007

AbstractStoichiometric Ni3V undergoes a cubic → tetragonal ordering transition (Al → DO22) by means of nucleation and growth. Electron diffraction microscopy and other experimental techniques reveal that the reaction is continuous, proceedind in three stages: I. Nucleation of coherent particles of the ordered phase in clusters of common orientation; II. Growth of these clustered nuclei to impingement forming isolated cells of unique orientation ‐ each cell is subdivided into anti‐phase domains; III. Growth of the cells to consume the remaining disordered phase, producing a mosaic substructure of mutually orthogonal cells, or “transformation twins”. Severe internal strains develop during the sequence, and secondary structural changes, such as twinning and recrystallization, effect their relief.
X‐Ray Spectra and Electronic Structure of Elements at the End of the First Long Period from 29Cu to 34Se
Authors: Nemoshkalenko V. V. , Mindlina M. A. , Mamko B. P. 
Published: July 2007

AbstractThe form of the Kβ2,5‐bands of the elements Ni and Zn is shown to have a fine structure not previously observed. The comparison of the K‐, L‐, and M‐spectra of metallic Ni, Cu, Zn, and Ge demonstrates the localization of the localization of the 3d bands. In Ni the d‐symmetry states form a narrow sub‐band at the Fermi level, in Cu these states are shifted to lower energies, and the process continues with increasing atomic number of the element. The shape of the Kβ2,5‐band of Ni, Cu, and Zn is due to the overlap of the Kβ5‐ and Kβ2‐bands and represents mainly the distribution of p‐symmetry states in the outer energy band of these elements. The formation of the 4s‐level in Ge is discussed. It is concluded that p–d transitions must take place in CuNi alloys in the outer shell of the outer shell of the Ni atom.