bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integral Representation of the Incoherent Field in Disordered Materials II. Hall Current and Thermoelectric Phenomena
Authors: Lenk R. 
Published: July 2007

AbstractThe theory developed in I is generalized by the inclusion of a magnetic field or of a temperature gradient. Also in these more general situations the theory exhibits internal consistency with regard to the representation of the Hall current and the Onsager symmetry for thermoelectric phenomena. The Hall coefficient departs from its classical value in the case of small mean free path and has unique sign.
Dipole Force Tensors of Vacancy‐Type Defects in α‐Iron
Authors: Ong C. K. 
Published: July 2007

AbstractA computer simulation is made to calculate the dipole force tensors and relaxed volumes of vacancy‐type point defects in α‐iron, using a spline‐fit pairwise potential for α‐iron, derived by Johnson. The displacement fields around the point defects are also reported.
Influence of Electron‐‐Phonon Interaction on Electronic Heat Capacity of Nb
Authors: Zhdanov K. R. , Rakhmenkulov F. S. 
Published: July 2007

AbstractThe electronic heat capacity of Nb is obtained from the experimental specific heat data between 10 and 350 K. The heat capacity of the lattice is determined by using the available data on phonon density of states. It is shown, that the electronic specific‐heat coefficient is dependent on temperature. Comparisons are made with the theoretical works of Masharov and Grimvall. The qualitative fit is quite good.
Effective Interactions in Jellium Including Exchange
Authors: Brosens F. , Devreese J. T. 
Published: July 2007

AbstractExplicit calculations are presented for the effective interactions in the homogeneous electron gas between two test charges, between an electron and a test charge, and between two electrons. The calculations are performed in the local approximation using existing theories for treating dynamical exchange effects in the dielectric response. The relation between these different approaches is discussed. The most remarkable result is that two recent dynamical local‐field corrections in the static limit give rise to an attractive effective electron–electron potential near q = 2kF, without the intervention of phonons.
Electron Structure and X‐Ray Absorption Spectra of Potassium Chloride II. Effect of a Core Hole in the Cluster Approach
Authors: Vedrinskii R. V. , Gegusin I. I. , Datsyuk V. N. , Novakovich A. A. , Kraizman V. L. 
Published: July 2007

AbstractX‐ray K‐absorption spectra of potassium and chlorine for 27‐atom clusters KCl6K12Cl8 and ClK6Cl12K8 are calculated in the framework of the scattered wave method. The spectra obtained for the ground state of the cluster are in good agreement with infinite crystal ones which are calculated by the APW method. The dimensions of the cluster representative for the description of the X‐ray photoionization process in solids are discussed. The influence of the ls‐hole potential on the spectrum shape is investigated in the cluster approach. A fair correlation between the theoretical and experimental spectra is obtained. It is shown that it is necessary to take into account the deep hole potential for a correct calculation of X‐ray absorption cross‐sections.
Calculation of the Equilibrium Mean Charge of Helium Ions
Authors: Kaneko T. , Ohtsuki Y. H. 
Published: July 2007

AbstractZ2‐oscillation of the equilibrium mean charge of 1 MeV He ions discovered by experiments is confirmed by calculating both the electron‐capture and ‐loss cross‐sections, employing two‐state atomic expansion method and Bron approximation, respectively. The calculations are in good agreement with the experimental results.
Bond Hybrids and the Structures of the Lanthanide Metals
Authors: Langley R. H. 
Published: July 2007

AbstractThe ideas developed by Altmann, Coulson, and Hume‐Rothery to relate bond hybrids to metal structures are extended to include treatment of the f orbitals. A discussion of the possible hybrids along with their application to the lanthanide metals will be considered.
Relative Stability and Structural Phase Transitions in Alkaline Earth Chalcogenide Crystals
Authors: Singh R. S. , Jain V. K. , Shanker J. 
Published: July 2007

AbstractUsing some recently developed interionic potentials the problem of relative stability and structural phase transition is studied in fifteen alkaline earth chalcogenides. The NaCl structure is found to be more stable than the CsCl structure for all the chalcogenides under study. This prediction is in agreement with the experimental facts. The cohesive energies and volume changes due to structural transformation are calculated and discussed in the light of experimental data.
Comments on the Pressure Variation of the Gibbs Energy for Bound and Unbound Defects
Authors: Varotsos P. , Alexopoulos K. , Nomicos K. 
Published: July 2007

AbstractThe pressure derivative v of the Gibbs energy g for “unbound” and “bound” defects (i.e. vacancies or interstitials attracted by aliovalent impurities) is studied. It is shown that for the formation and migration of defects the ratio v/g depends solely on well‐known macroscopic properties; applications are presented for self‐diffusion in f.c.c. and b.c.c. metals and for ionic conductivity of silver halides. In the case of ionic solids containing “bound” defects, a gradual variation of pressure results in the appearance of a transient polarization or depolarization current that maximizes at a certain pressure Pcr. The way of analysing this piezo‐stimulated current (PSC) spectrum is discussed. The fact that the value of Pcr does not have to coincide with the pressure at which fracture occurs provides a useful tool for applying PSC to geophysics.
The Influence of the Dynamic Jahn‐Teller Effect on the Phonon‐Scattering Mechanism at Acceptors in Semiconductors with Cubic Symmetry
Authors: Sigmund E. , Lassmann K. 
Published: July 2007

AbstractPhonon scattering experiments of various types in cubic semiconductors doped with deep effective mass acceptors indicate an extra resonance scattering at some meV. It is shown, using Green's function and transformation techniques that these resonances are due to a dynamic Jahn‐Teller effect of the Γ8 acceptor ground state.
Magnetic Properties of Oxygen Monolayers Adsorbed on Graphite
Authors: Diep‐The‐Hung  , Motchane J. L. 
Published: July 2007

AbstractThe in‐plane collinear antiferromagnetic structure of two‐dimensional distorted triangular lattice of solid oxygen molecules is shown to have the origin in intermolecular magnetic dipole–dipole interaction. By including this dipolar interaction in the isotropic Heisenberg Hamiltonian the intermolecular exchange integrals are calculated between nearest and next‐nearest neighbours, using availale neutron scattering and X‐ray diffraction data of oxygen monolayer adsorbed on graphite. Temperature dependence of sublattice magnetization is also shown and discussed.
Coulomb (or Strong) Correlation Effects in the Band Structure of Eu2O3
Authors: López‐Aguilar F. , Costa‐Quintana J. , Muñoz J. S. 
Published: July 2007

AbstractTwo band‐structure calculations of Eu2O3 are performed, one of them in the metallic phase and the other in the semiconducting phase; the difference between the corresponding band Hamiltonians is the occupation potential U (r) that includes the Coulomb correlation effects. In both phases, the 4f occupied bands are mixed with the 2p bands; this fact broadens these 4f bands so that its calculation is possible in this complex crystal lattice T. In the semiconducting band structure, the 4f empty bands are localized in the d‐zone energy showing (4f, 5d) hybridization that produces a broadening still greater than for the 4f occupied bands. The semiconducting gap is Γ – H and its value is 3.7 eV.
Discrete Saturation Effects of the ESR Spectrum of H0 in CaF2
Authors: Hornos Y. M. M. , Panepucci H. , Magon C. J. , Terrile M. C. 
Published: July 2007

AbstractSeveral experiments involving pulse saturation of ESR transitions of H0 in CaF2 are presented. The results are discussed and shown to arise from the mechanism of discrete saturation.
Electronic Energy Bands of Some AgMg, CuAl, and AlLi Alloys
Authors: Raychaudhuri M. , Chatterjee S. 
Published: July 2007

AbstractThe complex energy band structures of the substitutional alloys AgMg, CuAl, and AlLi are presented for 13 and 27 at% of Mg in AgMg, 5 and 15 at% of Al in CuAl, and 5 at% of Li for AlLi. The averaged T‐matrix approximation in conjunction with the KKRZ method is applied to the calculation of the complex energy bands and the Fermi surfaces of the alloys are evaluated from these data. The experimental optical spectra are discussed in the light of band to band transitions of the theoretically found band structures. The effect of charge transfer is also studied for a AgMg alloy with 27 at% Mg. The theoretically obtained Fermi surfaces are compared favourably with the experiment.
Effect of Magnetostatic Field on the Stimulated Raman Scattering of Transversely Polarized Electromagnetic Waves and Raman Instability in Semiconductor Plasmas
Authors: Ghosh S. , Agrawal V. K. 
Published: July 2007

AbstractThe stimulated Raman scattering of a large amplitude transversely polarized electromagnetic pump wave from both, the electron plasma wave and the molecular vibrations produced at a frequency equal to that of transverse optical phonon, is investigated in an n‐type semiconductor plasma. The general dispersion relation is obtained considering only the Stokes' component of the scattered electromagnetic wave in the presence of a large magnetostatic field applied at an arbitrary angle to the direction of propagation of the pump wave. The analysis is applied to both the cases of isotropic (B0 = 0) and magnetoactive (B0 ± 0) plasmas. The threshold electric field necessary for the onset of Raman instability and the growth rate of the unstable mode well above the threshold is studied. It is concluded that the threshold pump amplitude as well as the growth rate have strong dependence on the orientation of the magnetostatic field with respect to the wave vectors k, k1 and its magnitude.
Compression Effect on the Lattice Dynamics of Alkali Metals
Authors: Soma T. , Kimura Y. , Kagaya H.‐M. 
Published: July 2007

AbstractThe lattice dynamics of alkali metals under pressure is investigated using the second‐order perturbation and the local Heine‐Abarenkov model potential. Then, using the long‐wave phonon‐velocity method, the bulk modulus, and the shear elastic constants under compression are studied theoretically.
Thermodynamics of Aluminium and Magnesium‐Base Interstitial Solutions II. Energy of Mixing of Binary and Ternary Alloys
Authors: Bogdanov V. I. , Mikhailov A. V. , Fuks D. L. 
Published: July 2007

AbstractThe energy of disordered solid interstitial solutions and the energy of mixing in these solutions up to the second order of perturbation theory in pseudopotential is discussed. The correspondence of items, defining the band structure energy in interstitial and substitutional solutions is established. A comparative analysis of the contributions to the total energy of boron and carbon solutions in aluminium is performed. Numerical calculations show that the increase of impurity concentration results in the relaxation of elastic stresses, which is indicated by the decrease of quasielastic Fourier‐transform forces. The applicability of the perturbation theory in pseudopotentials limited to second‐order terms in the calculations of the energy of mixing in dilute interstitial solutions is analyzed. The alloying effect on the positive energy of mixing is discussed.
Optical Investigations on HfCxN1−x Compounds
Authors: Fluck F. W. , Geserich H. P. , Politis C. 
Published: July 2007

AbstractA report is given on the spectral reflectance of polycrystalline samples of HfCxN1‐x compounds in the energy range between 0.1 and 6.2 eV. The composition of the samples is gradually varied between pure nitride and pure carbide. The experimental reflectance data are analyzed by a Lorentz‐Drude model in order to determine both, the dependence of the interband absorption and of the free carrier concentration on the nitrogen to carbon ratio of the samples.
The Heat Capacity of LaNi2, LaNi5, PrNi2, and PrNi5 in the Temperature Range between 0.3 and 7 K
Authors: Sahling A. , Frach P. , Hegenbarth E. 
Published: July 2007

AbstractHeat capacity measurements of LaNi2, LaNi5, PrNi2, and PrNi5 in the temperature range of 0.3 to 7 K are presented and discussed. For Pr compounds a Schottky contribution to the heat capacity is found and compared with the value computed from the crystal field level scheme determined by inelastic neutron scattering. Below 1 K, for PrNi2 a T−2‐term is observed, which is connected with the occurrence of a nuclear magnetic ordering below 0.25 K.
Photoemission Studies of Crystalline Arsenic
Authors: Raisin C. , Bertrand Y. , Robin J. 
Published: July 2007

AbstractThe electronic band structure of crystalline arsenic is studied by ultraviolet photoemission spectroscopy. Angle‐integrated photocurrent is measured using a retarding field method and energy distribution curves are thus obtained in the 7.5 to 27.4 eV range. The numerous structures seen on energy distribution curves are identified as high density‐of‐state peaks. These experimental results are fruitfully compared to the calculated valence band structure of As.
Energy of Anion Polarization in Layered Structures
Authors: Urusov V. S. , Dudnikova V. B. 
Published: July 2007

AbstractIn layered structures the anion position has low local symmetry. The result are induced anion dipoles which strongly interact with each other and with all the remaining crystalline matrix. Two different approaches are examined to take account of the anion polarization energy in layered structures. The lattice energy is calculated with regard to the anion polarization term for some halides of bivalent metals (Mg, Ca, Cd, Mn, Pb). The polarization correction to lattice energy is found to be large, 3 to 4 eV. Impurity dissolution energies are recalculated for those cases where the pure impurity component forms a layered structure: their values are found to be positive and correct in order of magnitude.
Low‐Temperature Conductivity and Mobility in Semiconductors
Authors: Gegechkori T. O. , Yakeli V. G. , Kachlishvili Z. S. 
Published: July 2007

AbstractThe influence of the free‐carrier concentration upon the low‐temperature conductivity is investigated. The variation may be due either to temperature effects (under thermal equilibrium conditions) or to the influence of an electric field (under non‐equilibrium conditions). The effect considered is significant up to the temperature at which the free‐carrier concentration saturates and for the thermal electrons at low compensation ratio. Then the low‐temperature conductivity considered as a function of the temperature and electric field strength acquires a sharp minimum while the maximum of the conductivity becomes higher and shifts towards lower temperatures and smaller fields. The comparison with experimental data shows quite a good agreement between the experimental and theoretical curves. This suggests that the mobility minimum which for rather a long time was being observed and not understood is due to the effects discussed above. The cascade electron capture cross‐section of the ionized donors is re‐calculated using the sticking probability corrected by Abakumov and Yassevich. The result is used to calculate the capture coefficient in a strong electric field.
Free Induction of E1'‐Centres in Crystalline Quartz
Authors: Fedoruk G. G. , Rutkovskii I. Z. 
Published: July 2007

AbstractThe results of an experimental investigation of the free induction of E‐centres in crystalline quartz are presented. The EPR technique based on the pulsed change of the polarizing magnetic field is used. The magnetic system being coherently excited is controlled by the transient oscillations of the absorption signal. It is shown that the transient oscillation and free induction features cannot be described by the Bloch model.
Study of Rearrangements of Intrinsic Defects at Annealing of Proton‐Irradiated Silicon
Authors: Kuznetsov V. I. , Lugakov P. F. 
Published: July 2007

AbstractRearrangement processes proceeding during annealing of electrically active radiation defects in heavily irradiated (30 MeV protons) Si when the concentration of primary defects induced exceeds the concentration of impurities available in crystal are studied. Czochralski grown and vacuum floating‐zone n‐ and p‐type silicon (ϱ = 3 to 500 Ω cm) are used. Experimental results obtained from the analysis of the Hall coefficient temperature dependences show that the rearrangement of intrinsic structural defects (diinterstitials and multivacancy complexes) occurs predominantly during annealing. Accumulation kinetics is studied and temperature stability range of some multivacancy complexes contributing to the forbidden gap energy levels Ev + 0.29 eV (400 to 650 °C), Ev + 0.32 eV (500 to 750 °C), Ev + 0.22 eV (500 to 700 °C), Ev + 0.15 eV (500 to 800 °C), Ev + + 0.10 eV (600 to 750 °C), Ec −0.24 eV (500 to 850 °C) most of which are acceptor levels is determined. The diinterstitial (Si‐B3) center being annealed in the temperature range 300 to 500 °C is supposed to be a multicharge defect and has deep acceptor ( Ec −0.40 eV) and donor ( Ev + 0.35 eV) levels.
Electronic Structure of 3d and 4d Impurities in Mo and Nb
Authors: Podloucky R. , Deutz J. , Zeller R. , Dederichs P. H. 
Published: July 2007

AbstractCalculations are presented for the electronic structure of 3d and 4d‐ impurities in Mo and Nb. Using the density functional theory in the local spin density approximation of Barth and Hedin the electronic structure of the impurity is calculated by the KKR Green's function method. The impurity is described by a single perturbed muffin‐tin potential which is determined self‐consistently. In Nb and Mo 4d‐ impurities with the same excess valence ΔZ show very similar density of states. All 4d‐ impurities are unmagnetic. In Mo, of all 3d‐ impurities only Mn, Fe, and Co are magnetic. InNb, the formation of local moments of 3d‐ impurities is uncertain according to the present calculations. The occurrence of the local moments cannot be understood by the Friedel‐Anderson concept based on virtual bound states. Rather the simple “covalent model” of magnetism recently introduced by Williams et al. gives a reasonable description of the spin polarized densities of states.
Scattering of Surface Polaritons by the Order Parameter Fluctuations in the Vicinity of a Phase Transition Point
Authors: Ponath H.‐E. , Strizhevskii S. V. 
Published: July 2007

AbstractThe scattering theory of surface polaritons (SP) by polarization fluctuations with formation of bulk waves in media propagating from the interface is accounted. It is supposed that dielectric permeability of the contacting media is negative (without dissipation) on the scattering frequency. The theory is applied to SP scattering by Debye relaxation soft mode. The temperature dependence of scattering intensity is analysed. The angle and polarization characteristics of scattering are concretized for the cubic crystal case.
X‐Ray Spectroscopic Investigation and Calculation of the Energy Band Structure of Rare Earth Monophosphide and Monosulphide
Authors: Gusatinskii A. N. , Alperovich G. I. , Soldatov A. V. 
Published: July 2007

AbstractA joint X‐ray spectroscopic investigation is made of rare earth (RE) monophosphides and monosulphides, crystallizing in the NaCl‐type lattice, and the band calculation of some of them. X‐ray emission K‐ and L‐bands of phosphorus in RE monophosphides are obtained, and also the K absorption edges, K‐ and L‐emission bands of sulphur in RE monosulphides. From the results of the band calculation the dispersion curves are constructed, the total and local partial density of states is determined and the dependence of forbidden band width in monophosphides from the RE atomic number is obtained. The energy structures of the valence electron bands of investigated classes of compounds are similar in their principal features. Differences observed near the top of the band, essential for determination of physical properties, are connected with the localization of d‐ and f‐states. The possibility of X‐ray spectroscopic investigation of interatomic and intraatomic hybridizations is discussed, including shells, preceeding the valence ones, the electronic states of which can noticeably participate in the chemical bond. The nature of chemical interaction in the compounds studied is far from pure ionic, but is more polar than in compounds with a diamond‐like lattice.
Hot‐Carrier Galvanomagnetic Effects in High Magnetic Fields
Authors: Khan F. A. , Bhattacharya D. P. 
Published: July 2007

AbstractBy using the Boltzmann transport equation the low‐temperature galvanomagnetic effects due to non‐equilibrium charge carriers in a covalent semiconductor are investigated in the presence of a high (non‐quantizing) magnetic field. The energy and momentum of the free carriers are assumed to be scattered, respectively, by deformation acoustic phonons and static imperfections in order to obtain the energy distributions among them at low temperatures. The galvanomagnetic coefficients are calculated for the weakly and also for the strongly heated charge carrier systems. The results may be used to yield information of the characteristics of different trapping centres and also to determine the dominant scattering mechanism of the free carriers.
Investigation of Transport Coefficients in Semimetals by the Variational Method. II. Bismuth
Authors: Gitsu D. V. , Golban I. M. , Kantser V. G. 
Published: July 2007

AbstractA comparison of the experimental and calculated data for the transport coefficients in bismuth obtained on the basis of the variational microscopic model is carried out. The assumption about the predomination of carrier scattering on acoustic phonons in bismuth is confirmed. The values of deformation potential constants are calculated for a wide range of temperatures. The temperature and magnetic field dependences of transport coefficients in the wide range of temperatures and magnetic fields determined by variational method, completely reproduce the experimental data.
Ultrasound Modulation of γ‐Radiation in a Medium with Inhomogeneous Distribution of Mössbauer Nuclei
Authors: Mitin A. V. 
Published: July 2007

AbstractProgress and applications of the theory of the inhomogeneous ultrasound modulation of γ‐radiation are treated. A new mathematical formalism of the theory is developed. In the self‐absorption case, an exact solution is given for a sample thin with respect to ultrasound absorption but thick with respect to γ‐ray resonance absorption. The possibility of observing “inner” ultrasound resonances of γ‐radiation on Mössbauer nuclei with hyperfine structure is shown. On the basis of the theory developed a method is suggested to determine the distribution of Mössbauer nuclei from γ‐ray resonance absorption data. Experiments dealing with the generation of ultrasound in ferromagnetic metals are compared with theory.
Integral Representation of the Incoherent Field in Disordered Materials III. Diffusion, Einstein Relation, and Landauer Formula
Authors: Lenk R. 
Published: July 2007

AbstractThe theory developed in Part I of this paper is applied to the diffusion problem, i.e. without driving forces in the medium. The diffusion coefficient is connected with the mobility determined previously by the Einstein relation. For one‐dimensional systems of finite length the transmission coefficient is calculated starting from the basic integral equation for the density. As expected, this coefficient is related to the mobility by the Landauer formula.