bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction of Rare Gas Interstitials with Lattice Defects in Sr‐doped Potassium Halides
Authors: Felix F. W. , Müller M. 
Published: July 2007

AbstractResults are presented on Ar diffusion in single crystals of Sr‐doped KF, KCI, KBr, and KI. Ar was homogeneously distributed in the crystals during a neutron irradiation by the reaction K‐41(n, p)Ar‐41. It was verified, that cation vacancies, which were introduced by the irradiation were annealed out when diffusion became detectable, i.e. above 200 °C. Any influence on gas diffusion could therefore be attributed to the divalent doping alone, that is to the consequently introduced cation vacancies. The concentration of these vacancies was determined by measuring the ionic conductivity. In the case of KF, KCI, and KBr but not in the case of KI the gas mobility was reduced with respect to the pure crystals. Thus, the cation vacancies seem to act as gas traps in KF, KCI, and KBr. These effects have been predicted by Norgett and Lidiard [3] on the basis of theoretical calculations of migration and binding energies of mobile Ar interstitials.
Multiple Scattering of Thermal Neutrons by a Perfect Crystal. I. General Foundations
Authors: Lenk R. , Solbrig H. 
Published: July 2007

AbstractThe wave function of a neutron in a regular crystal is built up as a superposition of a primary plane wave and outgoing spherical waves. The elastic scattering properties of the nuclei are given exactly by their complex scattering amplitude f. It is carefully distinguish‐ed between the total wave field and the arriving field at any scattering centre. This results in a correct and consistent description of absorption effects. In the case of an infinite crystal slab the construction of the wave field is simplified by a lattice plane method: all the spherical waves coming out from such an infinite lattice plane add to plane waves, most of them are strongly damped with increasing distance from the plane. The undamped waves give the far‐field, which contains all the interesting informations about the collective interference effects. Neglect of the damped waves gives a good starting point for the approach given in the following two parts of this paper.
Magnetic Properties and the Invar Effect of Iron–Nickel Alloys
Authors: Dubinin S. F. , Sidorov S. K. , Valiev E. Z. 
Published: July 2007

AbstractOn the basis of a unified physical model calculations are made of the concentrational dependence of Curie temperature, the temperature dependence of magnetization, and the invar effect of the iron‐nickel alloys using the effective field method. It is shown that the results are in good agreement with experimental data.
Electron Microscopy Study of the “Direct Resolution” of Periodic Antiphase Boundaries, with Special Reference to Ag3Mg
Authors: Vanderschaeve G. 
Published: July 2007

AbstractIn a long period ordered alloy, interference between superlattice and satellite beams allows to obtain fringe systems, the characteristics of which are analysed within the two beam kinematical theory of electron diffraction. Expressions for the intensity are given in the different cases and fit with electron microscopy observations performed on an Ag3Mg alloy of 22 at% Mg composition. These observations show conclusively that antiphase boundaries occur regularly on every second (100) plane for such a concentration.
The Influence of Sulphur Substitution on the Magnetic Properties of Uranium Monoarsenide
Authors: Leciejewicz J. , Murasik A. , Troć R. , Palewski T. 
Published: July 2007

AbstractThe magnetic properties of the UAs‐US solid solution have been studied using neutron‐diffraction and magnetic methods. The low‐temperature magnetic phase of UAs was found to be stabilized by the addition of sulphur in a wide range of temperatures and compositions. The transition to a ferromagnetic structure of US proceeds through a transient phase. Its magnetic structure has been determined to be of longitudinal static spin wave type with cosinusoidal modulation. Its periodicity is 2.5 a, where a is the lattice constant of a f.c.c. crystallographic unit cell.
Galvanomagnetic Properties and Band Structure of the BiSbAs System
Authors: Shakhtakhtinskaya M. I. , Tomtiev D. S. 
Published: July 2007

AbstractThe galvanomagnetic properties of Bi75–xSb25Asx solid solutions with As concentration up to 3 at% has been measured at 77 °K. The results are interpreted in terms of a two‐carrier multi‐valley band model. It is shown that the axial ratio of the electron and hole ellipsoids in the BiSbAs system is decreased in comparison with pure Bi and Sb. The shape of the Fermi surfaces of the electrons and holes in the BiSbAs alloy system is equal to that of Bi75Sb25.
X‐Ray Coloration of Eu2+‐Doped KCl
Authors: Chowdari B. V. R. , Itoh N. 
Published: July 2007

AbstractThe irradiation effects in KCl doped with Eu2+ have been studied by measuring the optical absorption and EPR spectra. Exposure to X‐rays at room temperature and dry ice temperature leads to a decrease in the intensity of the absorption bands and the EPR lines of Eu2+. The decrease in Eu2+ is partially recovered by F‐bleaching at room temperature. Conversion of the Eu2+ to Eu3+ by trapping a hole at room temperature and dry ice temperature and the conversion of the Eu3+ to Eu2+ by trapping an electron at room temperature is suggested. X‐irradiation at liquid nitrogen temperature produced higher concentration of the Hayes‐Nichols centre than the X‐irradiation at dry ice temperature. This difference in the formation rate of the Hayes‐Nichols centre is attributed to the difference in the Eu2+ concentration at two different temperatures. A plausible model for the Hayes‐Nichols centre is suggested.
Absorption and Emission Spectra of NaCl:Ag Crystals Containing Oxygen and Calcium Impurities
Authors: Kaiser R. , Ludewig K. , Möller W. 
Published: July 2007

AbstractOptical absorption and emission of NaCl crystals doped with different silver concentrations and containing various contaminations of calcium and oxygen were investigated. The amounts of silver, calcium, and oxygen were determined by neutron activation analysis. Two absorption bands at 250 and 260 nm show the same temperature dependence between 80 and 300 °K as the F centre absorption in NaCl. Silver and oxygen are necessary for the centre, but our data provide no conclusive evidence that calcium is involved. The emission spectrum consists of three distinct bands at 350, 380, and 450 nm, which are interpreted.
Dynamic Susceptibility of an Itinerant Antiferromagnet in a Magnetic Field
Authors: Caillé A. 
Published: July 2007

AbstractThe dynamic susceptibility of an itinerant antiferromagnetic metal is calculated in the random phase approximation in an external magnetic field. The model used applies to metallic chromium below its spin‐flip temperature. The static limit of the susceptibility is obtained for both the long‐wavelength limit and the wave vector Q of the spin density wave. The spin‐wave dispersion relation is obtained for both the above limits.
Sharp‐Line Photoluminescence in Cadmium Telluride
Authors: Noblanc J. P. , Duraffourg G. 
Published: July 2007

AbstractThe photoluminescence spectrum of CdTe has been studied in the 1.4 to 1.5 eV range. New lines have been observed in several samples. The sharp lines are interpreted in terms of annihilation of excitons bound to single, or pairs of, isoelectronic impurities (probably oxygen).
Magnetophonon Resonances in Polar Semiconductors
Authors: Peterson R. L. , Magnusson B. , Weissglas P. 
Published: July 2007

AbstractThe first numerical calculations are reported of electrical transport properties in polar semiconductors in the non‐ohmic regime, for large to intermediate magnetic fields parallel to an electric field. Magnetophonon resonances in such properties as magnetoresistance and acoustoelectric gain are demonstrated. The results obtained generally confirm the hot electron interpretation by Dolat and Bray of their magnetoacoustoelectric experiments in n‐InSb.
Optical Absorption Spectra of Copper Ammonium Sulphate Hexahydrate Single Crystals Diluted with Magnesium Ammonium Sulphate Hexahydrate
Authors: Mathur S. C. , Bansal S. L. , Goel V. P. 
Published: July 2007

AbstractThe optical absorption study on the effect of solid dilution on tutton salts has been extended to the case of copper ammonium sulphate single crystals diluted with magnesium ammonium sulphate, and the change of crystal field symmetry from tetragonal to rhombic, on dilution, has been established.
Piezoresistance and Magnetopiezoresistance of n‐Ge in the [110] Direction
Authors: Baranskii P. I. , Buda I. S. , Dakhovskii I. V. , Kolomoets V. V. 
Published: July 2007

AbstractThe piezoresistance and magnetopieresistance were investigated in n‐Ge (ne = 1.48 × 1013 cm−3) for X ∥︁ H ∥︁ [110] at T = 77 °K (0 ≦ |X| ≦ 6000 kp cm−2; 0 ≦ |H| ≦ 100 kOe). It is shown that in the range of magnetic saturation the longitudinal magneto‐resistance is approximately increased by 10 times when X ∥︁ [110] is altered from zero up to 6 × 103 kp cm−2. On the basis of anisotropic scattering theory the dependences ϱ = f(X), (f)x = f(H), (Δϱ/Δϱ0)x = f(X) (Δϱ/ϱ0)H = f(X) were calculated, using the constants of deformation potentials Eu = 16.4 eV, Ed = −6.4 eV and assuming that the uniaxial deformation results only in the redistribution of the current carriers between relatively shifted energy minima and does not change the shape of the equal‐energy surfaces in n‐Ge. The results of the experiments are in agreement with the theoretical calculations not only qualitatively but quantitatively. The use of some sets of constants Eu and Ed mostly used in modern literature (instead of the ones presented above) for the theoretical calculation of the dependence (Δϱ/ϱ0)H = 50 kOe = f(X) results in a great disagreement between the curves calculated and the experimental data at |X| < 3000 kp cm−2.
The reflection of low‐energy ions from a single crystal simulated by different models
Authors: Karpuzov D. S. , Yurasova V. E. 
Published: July 2007

AbstractThe reflection of argon ions with an energy of 50 to 500 eV from a copper single crystal is simulated on a digital computer. Three models are used to describe the interaction of the projectiles with the crystal: 1. the ion interacts in each moment only with the nearest crystal atom, 2. the ion interacts with all atoms of some microcrystallite whose atoms are assumed to be free, 3. the ion interacts with a microcrystallite of bound lattice atoms. For the Ar+–Cu and Cu–Cu interaction we use the Born‐Mayer potential. A comparison of the results on the spatial and energy distributions of the ions in the different models is made.
General features of field emission from semiconductors
Authors: Baskin L. M. , Lvov O. I. , Fursey G. N. 
Published: July 2007

AbstractA theory of field emission from p‐ and n‐type semiconductors is developed without use of the zero current approximation. It is demonstrated that in p‐type semiconductors, near the crystal boundary, a weakly conducting region is formed, depleted of mobile carriers which exerts a limiting influence on the current and results in a saturation region appearing in the current‐voltage curve. The saturation current value depends, essentially, on the generation rate of mobile carriers. In n‐type semiconductors this kind of region is not formed, and the phenomenon of saturation arises due to the limited generation rate throughout the whole depth of the sample.
Résonance paramagnétique électronique de l'ion Cr3+ dans la zircone monoclinique
Authors: Bacquet G. , Dugas J. , Escribe C. 
Published: July 2007

AbstractLes spectres de RPE d'ions Cr3+ introduits dans la zircone monoclinique montrent l'existence de deux types de centres. Ces spectres s'interprètent à l'aide d'un Hamiltonien du second ordre dont les constantes sont les měmes pour les deux défauts. Seule l'orientation des axes propres du tenseur de champ cristallin est différente.
Photoemission studies of MoS2
Authors: Williams R. H. , McEvoy A. J. 
Published: July 2007

AbstractMeasurements of photoelectron quantum yield and energy distributions, under uv irradiation of energy up to 10 eV, have been carried out on single‐crystal MoS2 faces exposed by cleavage in vacuum. The photoelectric work function Φ is found to be (4.55 ± 0.1) eV. The low value of Φ, the slow rise in yield, and the general shape of the energy distribution curves support the band model proposed by Connell et al. [5]. A maximum in the conduction band density of states is located 5 eV above the valence band edge, and structure in the valence band density of states is revealed. These results are compared with those obtained from uv reflectivity measurements.
Kohn's variational method for amorphous conductors
Authors: Gubanov A. I. 
Published: July 2007

AbstractA new method for quantum‐mechanical calculations of electronic states in a concrete amorphous material is proposed. This method is a modification of Kohn's variational method for crystals. The volume and surface integrals for one cell are replaced by the sum of integrals over all cells and intercellular boundaries. The linear combination describing the wave function in each cell includes terms accounting for the deformation of the cell; thus the correlation between local atomic configuration and electronic wave function is taken into consideration.
Calculation of the electronic energy spectrum for liquid alkali metals by Kohn's variational method
Authors: Gubanov A. I. , Starbunova T. A. 
Published: July 2007

AbstractNumerical calculations of the electronic energy spectrum of liquid alkali metals — the simplest amorphous conductors — are performed by Kohn's variational method, which was modified for amorphous conductors by one of the authors. Experimental binary atomic distribution functions are used. Diagrams are given for the electronic energy as a function of the average phase difference between neighbouring atoms.
Analysis of the elastic anomalies at the structural phase transition of SrTiO8 near 105 K
Authors: Pietrass B. 
Published: July 2007

AbstractExpressions are given for the elastic compliances, sij, and the elastic stiffnesses, cij, of the tetragonal phase which have been derived from the phenomenological theory of the phase transition. The discontinuities of the elastic constants at the transition are calculated from the tetragonal distortion and the stress dependence of the transition temperature and compared with those obtained from sound velocity and Brillouin scattering data.
Structure of liquid antimony by neutron diffraction
Authors: Waseda Y. , Suzuki K. 
Published: July 2007

AbstractNeutron diffraction patterns from liquid antimony have been obtained at 660 and 800 °C. The structure factors are nearly independent of temperature. Comparing the results with the structure of liquid bismuth and the hard sphere model the existence of two structure types in liquid antimony previously indicated seems to be ambiguous. The electrical resistivity was calculated using Ziman's theory [12] and compared with experimental data. From this in the case of liquid antimony the invalidity of the Born approximation in Ziman's theory was found.
Green's functions for anisotropic elasticity
Authors: Mura T. , Kinoshita N. 
Published: July 2007

AbstractGreen's functions describing the elastic displacement caused by a unit force in an infinitely extended anisotropic media are obtained in series form. The series and its derivatives uniformly converge contrary to the Green's functions obtained by previous investigators. The results are applicable to any type of anisotropy. A special example, requiring no computer calculation is given for the case of cubic crystals.
Impurities and intervalence band magneto‐optical transitions in tellurium
Authors: Hardy D. , Rigaux C. , Vieren J. P. , Hau Nguyen Hy 
Published: July 2007

AbstractRecent magneto‐optical results obtained in the energy range 100 to 170 meV, for ϵ ‖ c and H ⊥ c, are reported and analysed. Transitions of holes from acceptor states and transitions of holes from the first Landau level of the M band to the quantum levels of the M′1 band are identified by investigating the temperature dependence of the magnetoabsorption lines between 2 and 10°K. Calculations of the energies and intensities of the intervalence band magneto‐optical transitions are performed. The comparison of theoretical and experimental data enables one to determine the parameters of the valence band. The fine structure of magnetoabsorption spectra investigated by wavelength modulation technique indicates the existence of several impurity states. The binding energy of the acceptor ground state is estimated to be about 1.4 meV.
On the anisotropy of the exchange interactions in the ion radical salt (TCNQ)2‐3,3 diethyltiaearbocyanine
Authors: Fedutin D. N. , Shchegolev I. F. , Stryukov V. B. , Yagubskii E. B. , Zvarykina A. V. , Atovmyan L. O. , Kaminskii V. F. , Shibaeva R. P. 
Published: July 2007

AbstractAn investigation is made of the crystal structure, electron spin resonance (ESR), and static paramagnetic susceptibility of single crystals of the complex (TCNQ)2‐3,3 diethyltiacarbocyanine (DTC). It is shown that the splitting of the ESR spectra is due to the anisotropy of the g‐factors of non‐equivalent ion‐radical chains of TCNQ. The g‐tensor of a single ion‐radical chain of TCNQ is found to have molecular symmetry (gxx = 2.0026, gyy = 2.0034, gzz = 2.0021; all ±0.0003.) The existence of splitting of the ESR spectra gives evidence that there is no exchange interaction between non‐equivalent chains. However, the measurements of the static paramagnetic susceptibility and the linewidth analysis indicate that the intra‐chain exchange interaction I/K has a large value: 10 to 15°. Thus, our results show that the spin system in the complex (TCNQ),‐DTC is one‐dimensional.
Faraday rotation in amorphous CdGeAs2
Authors: Vorisek V. , Zvára M. 
Published: July 2007

AbstractResults of Faraday rotation measurements in the region of the absorption edge of amorphous CdGeAs2, at room and liquid nitrogen temperatures are presented. Comparison with the BHL and HLN formulae for the Faraday rotation of crystalline semiconductors yields room‐temperature values of the energy gap of 1.22 and 1.32 eV, respectively. The results are discussed in terms of the generally accepted model of amorphous semiconductors, and the gaps obtained are tentatively assigned to the mobility gap.
Acoustoelectric parametric interactions and other non‐linear effects in a piezoelectric semiconductor
Authors: Ridley B. K. 
Published: July 2007

AbstractThe theory describing departures from linear bchaviour of a single acoustic wave in a piezoelectric semiconductor is extended to include the case of many waves. In addition to the self‐interaction of each wave and the excitation of its associated evanescent mode, there appear in lowest order the three‐wave parametric interactions. Only those parametric intcractions which are phase‐matched are considered. It is shown that the latter consist, of a normal part, obeying the Manley‐Rowe relations, and an anomalous part, associated with the carrier drift, which do not. Coupled with the parametric gain is a velocity shift whose phase is in quadrature with respect to that of the gain. It is pointed out that nonlinear velocity shifts destroy perfect phase‐matching. The down conversion rate maximises at the subharmonic, and the subharmonic generation rate rises with the frequency of pump to a maximum at about 2.3 ωm, where ωm is the frequency for maximum linear gain. In the weak‐activity regime and apart from parametric processes the non‐linear gain is current‐controlled and remains maximised at ωm. Observed frequency shifts may be due to the frequency dependence of the lattice loss as well as that for subharmonic generation.
Treatment of the electronic structure of the F+ centre in some 11‐VI semiconductors in an effective‐charge point‐ion‐lattice approximation
Authors: Wruck D. 
Published: July 2007

AbstractThe ground and first cxcited state energies of the singly electron occupied anion vacancy (F+ centre) in xincblende and wurtzite II‐VI semiconductors are calculated in a point‐ion‐lattice approximation in which the partially ionic binding character of these compounds is accounted for by introducing an effcctive ionic charge. Restricting to the spherically symmetric component of the defect potential and using hydrogenic 1s and 2p trial functions, the energies and the Corresponding Bohr radii of the F+ centre electron are given as a function of the effcctive ionic charge. Taking appropriate values for the effective ionic charge and for the position of the conduction band with respect to the vacuum level, the location of the ground and excited state levels with respect to the conduction band, the optical transition energies, as well as the corresponding Bohr radii are estimated for CdS, ZnS, and ZnO.
Phonon‐induced self‐energy and mass enhancement of electrons in metals
Authors: Teichler H 
Published: July 2007

AbstractThe phonon‐induced energy correction of electrons in metals and the resulting change of the effective mass are formulated by means of localized functions (i.e. generalized Wan‐nier functions). This formulation makes it possible to take into account, in a simple way, the experimentally observed anisotropies of the Fermi surface and the Fermi velocity. The periodicity of reciprocal space is preserved, thus all “Umklapp” processes are included. As an application of this formulation the κ‐dependent mass enhancement parameter λ(κ) is evaluated for Cu. λ(κ) varies from 0.086 (in 〈100〉 direction) up to 0.185 (at the neck of the Fermi surface); the average is found to be 0.15.
On the theory of the electric conductivity of solids in a strong electric field
Authors: Enderlein R. , Peuker K. 
Published: July 2007

AbstractA theory of the electric conductivity is given for a simple semiconductor model in the presence of a strong electric field including both the heating of the charge carriers and the field‐induced change of the density of states. The conductivity is divided into an interband and an interband part. The intraband part defines the field‐dependent plasma frequency. The interband conductivity vanishes in absence of the strong field and shows an exponential growth as the field is increased. The connection of this result with the Zener tunneling of electrons between the valence and the conduction bands is discussed.
Diffusion and transport in strain gradients
Authors: Frohberg G. 
Published: July 2007

AbstractThe effect of a strain gradient on the drift velocity and the effect of the strain on the migration energy of point defects are deduced in terms of double force tensors associated with the defect in the stable lattice position and the saddle point position. General equations for the force of transport and the migration energy are deduced and discussed for special cases of strains and double force tensors; the relation to relaxation and activation volumes is given.
Influence of impurities on the de haas‐van alphen effect II. Application to point defects in copper
Authors: Hehl W. , Mann  
Published: July 2007

AbstractA recent theory for the effects of localized defects in metals on the amplitudes and the periods of the de Haas‐van Alphen oscillations is applied to point defects in copper. The parameters characterizing a defect in the employed model are fixed by means of the neutrality condition and the residual resistivity. The calculations of the Dingle temperatures and the changes in period are carried out for the most important extremal orbits on the Fermi surface of copper as given by Halse. The agreement with the available experimental data is satisfactory. The calculated changes in the de Haas‐van Alphen periods are shown to differ not very much from those obtained in the rigid‐band model.